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diff --git a/doc/configuration.txt b/doc/configuration.txt new file mode 100644 index 0000000..be81b9a --- /dev/null +++ b/doc/configuration.txt @@ -0,0 +1,23704 @@ + ---------------------- + HAProxy + Configuration Manual + ---------------------- + version 2.6 + 2023/03/28 + + +This document covers the configuration language as implemented in the version +specified above. It does not provide any hints, examples, or advice. For such +documentation, please refer to the Reference Manual or the Architecture Manual. +The summary below is meant to help you find sections by name and navigate +through the document. + +Note to documentation contributors : + This document is formatted with 80 columns per line, with even number of + spaces for indentation and without tabs. Please follow these rules strictly + so that it remains easily printable everywhere. If a line needs to be + printed verbatim and does not fit, please end each line with a backslash + ('\') and continue on next line, indented by two characters. It is also + sometimes useful to prefix all output lines (logs, console outputs) with 3 + closing angle brackets ('>>>') in order to emphasize the difference between + inputs and outputs when they may be ambiguous. If you add sections, + please update the summary below for easier searching. + + +Summary +------- + +1. Quick reminder about HTTP +1.1. The HTTP transaction model +1.2. HTTP request +1.2.1. The request line +1.2.2. The request headers +1.3. HTTP response +1.3.1. The response line +1.3.2. The response headers + +2. Configuring HAProxy +2.1. Configuration file format +2.2. Quoting and escaping +2.3. Environment variables +2.4. Conditional blocks +2.5. Time format +2.6. Examples + +3. Global parameters +3.1. Process management and security +3.2. Performance tuning +3.3. Debugging +3.4. Userlists +3.5. Peers +3.6. Mailers +3.7. Programs +3.8. HTTP-errors +3.9. Rings +3.10. Log forwarding + +4. Proxies +4.1. Proxy keywords matrix +4.2. Alphabetically sorted keywords reference + +5. Bind and server options +5.1. Bind options +5.2. Server and default-server options +5.3. Server DNS resolution +5.3.1. Global overview +5.3.2. The resolvers section + +6. Cache +6.1. Limitation +6.2. Setup +6.2.1. Cache section +6.2.2. Proxy section + +7. Using ACLs and fetching samples +7.1. ACL basics +7.1.1. Matching booleans +7.1.2. Matching integers +7.1.3. Matching strings +7.1.4. Matching regular expressions (regexes) +7.1.5. Matching arbitrary data blocks +7.1.6. Matching IPv4 and IPv6 addresses +7.2. Using ACLs to form conditions +7.3. Fetching samples +7.3.1. Converters +7.3.2. Fetching samples from internal states +7.3.3. Fetching samples at Layer 4 +7.3.4. Fetching samples at Layer 5 +7.3.5. Fetching samples from buffer contents (Layer 6) +7.3.6. Fetching HTTP samples (Layer 7) +7.3.7. Fetching samples for developers +7.4. Pre-defined ACLs + +8. Logging +8.1. Log levels +8.2. Log formats +8.2.1. Default log format +8.2.2. TCP log format +8.2.3. HTTP log format +8.2.4. HTTPS log format +8.2.5. Error log format +8.2.6. Custom log format +8.3. Advanced logging options +8.3.1. Disabling logging of external tests +8.3.2. Logging before waiting for the session to terminate +8.3.3. Raising log level upon errors +8.3.4. Disabling logging of successful connections +8.4. Timing events +8.5. Session state at disconnection +8.6. Non-printable characters +8.7. Capturing HTTP cookies +8.8. Capturing HTTP headers +8.9. Examples of logs + +9. Supported filters +9.1. Trace +9.2. HTTP compression +9.3. Stream Processing Offload Engine (SPOE) +9.4. Cache +9.5. fcgi-app +9.6. OpenTracing + +10. FastCGI applications +10.1. Setup +10.1.1. Fcgi-app section +10.1.2. Proxy section +10.1.3. Example +10.2. Default parameters +10.3. Limitations + +11. Address formats +11.1. Address family prefixes +11.2. Socket type prefixes +11.3. Protocol prefixes + +1. Quick reminder about HTTP +---------------------------- + +When HAProxy is running in HTTP mode, both the request and the response are +fully analyzed and indexed, thus it becomes possible to build matching criteria +on almost anything found in the contents. + +However, it is important to understand how HTTP requests and responses are +formed, and how HAProxy decomposes them. It will then become easier to write +correct rules and to debug existing configurations. + + +1.1. The HTTP transaction model +------------------------------- + +The HTTP protocol is transaction-driven. This means that each request will lead +to one and only one response. Traditionally, a TCP connection is established +from the client to the server, a request is sent by the client through the +connection, the server responds, and the connection is closed. A new request +will involve a new connection : + + [CON1] [REQ1] ... [RESP1] [CLO1] [CON2] [REQ2] ... [RESP2] [CLO2] ... + +In this mode, called the "HTTP close" mode, there are as many connection +establishments as there are HTTP transactions. Since the connection is closed +by the server after the response, the client does not need to know the content +length. + +Due to the transactional nature of the protocol, it was possible to improve it +to avoid closing a connection between two subsequent transactions. In this mode +however, it is mandatory that the server indicates the content length for each +response so that the client does not wait indefinitely. For this, a special +header is used: "Content-length". This mode is called the "keep-alive" mode : + + [CON] [REQ1] ... [RESP1] [REQ2] ... [RESP2] [CLO] ... + +Its advantages are a reduced latency between transactions, and less processing +power required on the server side. It is generally better than the close mode, +but not always because the clients often limit their concurrent connections to +a smaller value. + +Another improvement in the communications is the pipelining mode. It still uses +keep-alive, but the client does not wait for the first response to send the +second request. This is useful for fetching large number of images composing a +page : + + [CON] [REQ1] [REQ2] ... [RESP1] [RESP2] [CLO] ... + +This can obviously have a tremendous benefit on performance because the network +latency is eliminated between subsequent requests. Many HTTP agents do not +correctly support pipelining since there is no way to associate a response with +the corresponding request in HTTP. For this reason, it is mandatory for the +server to reply in the exact same order as the requests were received. + +The next improvement is the multiplexed mode, as implemented in HTTP/2 and HTTP/3. +This time, each transaction is assigned a single stream identifier, and all +streams are multiplexed over an existing connection. Many requests can be sent in +parallel by the client, and responses can arrive in any order since they also +carry the stream identifier. + + +HTTP/3 is implemented over QUIC, itself implemented over UDP. QUIC solves the +head of line blocking at transport level by means of independently treated +streams. Indeed, when experiencing loss, an impacted stream does not affect the +other streams. + +By default HAProxy operates in keep-alive mode with regards to persistent +connections: for each connection it processes each request and response, and +leaves the connection idle on both sides between the end of a response and the +start of a new request. When it receives HTTP/2 connections from a client, it +processes all the requests in parallel and leaves the connection idling, +waiting for new requests, just as if it was a keep-alive HTTP connection. + +HAProxy supports 4 connection modes : + - keep alive : all requests and responses are processed (default) + - tunnel : only the first request and response are processed, + everything else is forwarded with no analysis (deprecated). + - server close : the server-facing connection is closed after the response. + - close : the connection is actively closed after end of response. + + + +1.2. HTTP request +----------------- + +First, let's consider this HTTP request : + + Line Contents + number + 1 GET /serv/login.php?lang=en&profile=2 HTTP/1.1 + 2 Host: www.mydomain.com + 3 User-agent: my small browser + 4 Accept: image/jpeg, image/gif + 5 Accept: image/png + + +1.2.1. The Request line +----------------------- + +Line 1 is the "request line". It is always composed of 3 fields : + + - a METHOD : GET + - a URI : /serv/login.php?lang=en&profile=2 + - a version tag : HTTP/1.1 + +All of them are delimited by what the standard calls LWS (linear white spaces), +which are commonly spaces, but can also be tabs or line feeds/carriage returns +followed by spaces/tabs. The method itself cannot contain any colon (':') and +is limited to alphabetic letters. All those various combinations make it +desirable that HAProxy performs the splitting itself rather than leaving it to +the user to write a complex or inaccurate regular expression. + +The URI itself can have several forms : + + - A "relative URI" : + + /serv/login.php?lang=en&profile=2 + + It is a complete URL without the host part. This is generally what is + received by servers, reverse proxies and transparent proxies. + + - An "absolute URI", also called a "URL" : + + http://192.168.0.12:8080/serv/login.php?lang=en&profile=2 + + It is composed of a "scheme" (the protocol name followed by '://'), a host + name or address, optionally a colon (':') followed by a port number, then + a relative URI beginning at the first slash ('/') after the address part. + This is generally what proxies receive, but a server supporting HTTP/1.1 + must accept this form too. + + - a star ('*') : this form is only accepted in association with the OPTIONS + method and is not relayable. It is used to inquiry a next hop's + capabilities. + + - an address:port combination : 192.168.0.12:80 + This is used with the CONNECT method, which is used to establish TCP + tunnels through HTTP proxies, generally for HTTPS, but sometimes for + other protocols too. + +In a relative URI, two sub-parts are identified. The part before the question +mark is called the "path". It is typically the relative path to static objects +on the server. The part after the question mark is called the "query string". +It is mostly used with GET requests sent to dynamic scripts and is very +specific to the language, framework or application in use. + +HTTP/2 doesn't convey a version information with the request, so the version is +assumed to be the same as the one of the underlying protocol (i.e. "HTTP/2"). + + +1.2.2. The request headers +-------------------------- + +The headers start at the second line. They are composed of a name at the +beginning of the line, immediately followed by a colon (':'). Traditionally, +an LWS is added after the colon but that's not required. Then come the values. +Multiple identical headers may be folded into one single line, delimiting the +values with commas, provided that their order is respected. This is commonly +encountered in the "Cookie:" field. A header may span over multiple lines if +the subsequent lines begin with an LWS. In the example in 1.2, lines 4 and 5 +define a total of 3 values for the "Accept:" header. + +Contrary to a common misconception, header names are not case-sensitive, and +their values are not either if they refer to other header names (such as the +"Connection:" header). In HTTP/2, header names are always sent in lower case, +as can be seen when running in debug mode. Internally, all header names are +normalized to lower case so that HTTP/1.x and HTTP/2 use the exact same +representation, and they are sent as-is on the other side. This explains why an +HTTP/1.x request typed with camel case is delivered in lower case. + +The end of the headers is indicated by the first empty line. People often say +that it's a double line feed, which is not exact, even if a double line feed +is one valid form of empty line. + +Fortunately, HAProxy takes care of all these complex combinations when indexing +headers, checking values and counting them, so there is no reason to worry +about the way they could be written, but it is important not to accuse an +application of being buggy if it does unusual, valid things. + +Important note: + As suggested by RFC7231, HAProxy normalizes headers by replacing line breaks + in the middle of headers by LWS in order to join multi-line headers. This + is necessary for proper analysis and helps less capable HTTP parsers to work + correctly and not to be fooled by such complex constructs. + + +1.3. HTTP response +------------------ + +An HTTP response looks very much like an HTTP request. Both are called HTTP +messages. Let's consider this HTTP response : + + Line Contents + number + 1 HTTP/1.1 200 OK + 2 Content-length: 350 + 3 Content-Type: text/html + +As a special case, HTTP supports so called "Informational responses" as status +codes 1xx. These messages are special in that they don't convey any part of the +response, they're just used as sort of a signaling message to ask a client to +continue to post its request for instance. In the case of a status 100 response +the requested information will be carried by the next non-100 response message +following the informational one. This implies that multiple responses may be +sent to a single request, and that this only works when keep-alive is enabled +(1xx messages are HTTP/1.1 only). HAProxy handles these messages and is able to +correctly forward and skip them, and only process the next non-100 response. As +such, these messages are neither logged nor transformed, unless explicitly +state otherwise. Status 101 messages indicate that the protocol is changing +over the same connection and that HAProxy must switch to tunnel mode, just as +if a CONNECT had occurred. Then the Upgrade header would contain additional +information about the type of protocol the connection is switching to. + + +1.3.1. The response line +------------------------ + +Line 1 is the "response line". It is always composed of 3 fields : + + - a version tag : HTTP/1.1 + - a status code : 200 + - a reason : OK + +The status code is always 3-digit. The first digit indicates a general status : + - 1xx = informational message to be skipped (e.g. 100, 101) + - 2xx = OK, content is following (e.g. 200, 206) + - 3xx = OK, no content following (e.g. 302, 304) + - 4xx = error caused by the client (e.g. 401, 403, 404) + - 5xx = error caused by the server (e.g. 500, 502, 503) + +Please refer to RFC7231 for the detailed meaning of all such codes. The +"reason" field is just a hint, but is not parsed by clients. Anything can be +found there, but it's a common practice to respect the well-established +messages. It can be composed of one or multiple words, such as "OK", "Found", +or "Authentication Required". + +HAProxy may emit the following status codes by itself : + + Code When / reason + 200 access to stats page, and when replying to monitoring requests + 301 when performing a redirection, depending on the configured code + 302 when performing a redirection, depending on the configured code + 303 when performing a redirection, depending on the configured code + 307 when performing a redirection, depending on the configured code + 308 when performing a redirection, depending on the configured code + 400 for an invalid or too large request + 401 when an authentication is required to perform the action (when + accessing the stats page) + 403 when a request is forbidden by a "http-request deny" rule + 404 when the requested resource could not be found + 408 when the request timeout strikes before the request is complete + 410 when the requested resource is no longer available and will not + be available again + 500 when HAProxy encounters an unrecoverable internal error, such as a + memory allocation failure, which should never happen + 501 when HAProxy is unable to satisfy a client request because of an + unsupported feature + 502 when the server returns an empty, invalid or incomplete response, or + when an "http-response deny" rule blocks the response. + 503 when no server was available to handle the request, or in response to + monitoring requests which match the "monitor fail" condition + 504 when the response timeout strikes before the server responds + +The error 4xx and 5xx codes above may be customized (see "errorloc" in section +4.2). + + +1.3.2. The response headers +--------------------------- + +Response headers work exactly like request headers, and as such, HAProxy uses +the same parsing function for both. Please refer to paragraph 1.2.2 for more +details. + + +2. Configuring HAProxy +---------------------- + +2.1. Configuration file format +------------------------------ + +HAProxy's configuration process involves 3 major sources of parameters : + + - the arguments from the command-line, which always take precedence + - the configuration file(s), whose format is described here + - the running process's environment, in case some environment variables are + explicitly referenced + +The configuration file follows a fairly simple hierarchical format which obey +a few basic rules: + + 1. a configuration file is an ordered sequence of statements + + 2. a statement is a single non-empty line before any unprotected "#" (hash) + + 3. a line is a series of tokens or "words" delimited by unprotected spaces or + tab characters + + 4. the first word or sequence of words of a line is one of the keywords or + keyword sequences listed in this document + + 5. all other words are all arguments of the first one, some being well-known + keywords listed in this document, others being values, references to other + parts of the configuration, or expressions + + 6. certain keywords delimit a section inside which only a subset of keywords + are supported + + 7. a section ends at the end of a file or on a special keyword starting a new + section + +This is all that is needed to know to write a simple but reliable configuration +generator, but this is not enough to reliably parse any configuration nor to +figure how to deal with certain corner cases. + +First, there are a few consequences of the rules above. Rule 6 and 7 imply that +the keywords used to define a new section are valid everywhere and cannot have +a different meaning in a specific section. These keywords are always a single +word (as opposed to a sequence of words), and traditionally the section that +follows them is designated using the same name. For example when speaking about +the "global section", it designates the section of configuration that follows +the "global" keyword. This usage is used a lot in error messages to help locate +the parts that need to be addressed. + +A number of sections create an internal object or configuration space, which +requires to be distinguished from other ones. In this case they will take an +extra word which will set the name of this particular section. For some of them +the section name is mandatory. For example "frontend foo" will create a new +section of type "frontend" named "foo". Usually a name is specific to its +section and two sections of different types may use the same name, but this is +not recommended as it tends to complexify configuration management. + +A direct consequence of rule 7 is that when multiple files are read at once, +each of them must start with a new section, and the end of each file will end +a section. A file cannot contain sub-sections nor end an existing section and +start a new one. + +Rule 1 mentioned that ordering matters. Indeed, some keywords create directives +that can be repeated multiple times to create ordered sequences of rules to be +applied in a certain order. For example "tcp-request" can be used to alternate +"accept" and "reject" rules on varying criteria. As such, a configuration file +processor must always preserve a section's ordering when editing a file. The +ordering of sections usually does not matter except for the global section +which must be placed before other sections, but it may be repeated if needed. +In addition, some automatic identifiers may automatically be assigned to some +of the created objects (e.g. proxies), and by reordering sections, their +identifiers will change. These ones appear in the statistics for example. As +such, the configuration below will assign "foo" ID number 1 and "bar" ID number +2, which will be swapped if the two sections are reversed: + + listen foo + bind :80 + + listen bar + bind :81 + +Another important point is that according to rules 2 and 3 above, empty lines, +spaces, tabs, and comments following and unprotected "#" character are not part +of the configuration as they are just used as delimiters. This implies that the +following configurations are strictly equivalent: + + global#this is the global section + daemon#daemonize + frontend foo + mode http # or tcp + +and: + + global + daemon + + # this is the public web frontend + frontend foo + mode http + +The common practice is to align to the left only the keyword that initiates a +new section, and indent (i.e. prepend a tab character or a few spaces) all +other keywords so that it's instantly visible that they belong to the same +section (as done in the second example above). Placing comments before a new +section helps the reader decide if it's the desired one. Leaving a blank line +at the end of a section also visually helps spotting the end when editing it. + +Tabs are very convenient for indent but they do not copy-paste well. If spaces +are used instead, it is recommended to avoid placing too many (2 to 4) so that +editing in field doesn't become a burden with limited editors that do not +support automatic indent. + +In the early days it used to be common to see arguments split at fixed tab +positions because most keywords would not take more than two arguments. With +modern versions featuring complex expressions this practice does not stand +anymore, and is not recommended. + + +2.2. Quoting and escaping +------------------------- + +In modern configurations, some arguments require the use of some characters +that were previously considered as pure delimiters. In order to make this +possible, HAProxy supports character escaping by prepending a backslash ('\') +in front of the character to be escaped, weak quoting within double quotes +('"') and strong quoting within single quotes ("'"). + +This is pretty similar to what is done in a number of programming languages and +very close to what is commonly encountered in Bourne shell. The principle is +the following: while the configuration parser cuts the lines into words, it +also takes care of quotes and backslashes to decide whether a character is a +delimiter or is the raw representation of this character within the current +word. The escape character is then removed, the quotes are removed, and the +remaining word is used as-is as a keyword or argument for example. + +If a backslash is needed in a word, it must either be escaped using itself +(i.e. double backslash) or be strongly quoted. + +Escaping outside quotes is achieved by preceding a special character by a +backslash ('\'): + + \ to mark a space and differentiate it from a delimiter + \# to mark a hash and differentiate it from a comment + \\ to use a backslash + \' to use a single quote and differentiate it from strong quoting + \" to use a double quote and differentiate it from weak quoting + +In addition, a few non-printable characters may be emitted using their usual +C-language representation: + + \n to insert a line feed (LF, character \x0a or ASCII 10 decimal) + \r to insert a carriage return (CR, character \x0d or ASCII 13 decimal) + \t to insert a tab (character \x09 or ASCII 9 decimal) + \xNN to insert character having ASCII code hex NN (e.g \x0a for LF). + +Weak quoting is achieved by surrounding double quotes ("") around the character +or sequence of characters to protect. Weak quoting prevents the interpretation +of: + + space or tab as a word separator + ' single quote as a strong quoting delimiter + # hash as a comment start + +Weak quoting permits the interpretation of environment variables (which are not +evaluated outside of quotes) by preceding them with a dollar sign ('$'). If a +dollar character is needed inside double quotes, it must be escaped using a +backslash. + +Strong quoting is achieved by surrounding single quotes ('') around the +character or sequence of characters to protect. Inside single quotes, nothing +is interpreted, it's the efficient way to quote regular expressions. + +As a result, here is the matrix indicating how special characters can be +entered in different contexts (unprintable characters are replaced with their +name within angle brackets). Note that some characters that may only be +represented escaped have no possible representation inside single quotes, +hence the '-' there: + + Character | Unquoted | Weakly quoted | Strongly quoted + -----------+---------------+-----------------------------+----------------- + <TAB> | \<TAB>, \x09 | "<TAB>", "\<TAB>", "\x09" | '<TAB>' + <LF> | \n, \x0a | "\n", "\x0a" | - + <CR> | \r, \x0d | "\r", "\x0d" | - + <SPC> | \<SPC>, \x20 | "<SPC>", "\<SPC>", "\x20" | '<SPC>' + " | \", \x22 | "\"", "\x22" | '"' + # | \#, \x23 | "#", "\#", "\x23" | '#' + $ | $, \$, \x24 | "\$", "\x24" | '$' + ' | \', \x27 | "'", "\'", "\x27" | - + \ | \\, \x5c | "\\", "\x5c" | '\' + + Example: + # those are all strictly equivalent: + log-format %{+Q}o\ %t\ %s\ %{-Q}r + log-format "%{+Q}o %t %s %{-Q}r" + log-format '%{+Q}o %t %s %{-Q}r' + log-format "%{+Q}o %t"' %s %{-Q}r' + log-format "%{+Q}o %t"' %s'\ %{-Q}r + +There is one particular case where a second level of quoting or escaping may be +necessary. Some keywords take arguments within parenthesis, sometimes delimited +by commas. These arguments are commonly integers or predefined words, but when +they are arbitrary strings, it may be required to perform a separate level of +escaping to disambiguate the characters that belong to the argument from the +characters that are used to delimit the arguments themselves. A pretty common +case is the "regsub" converter. It takes a regular expression in argument, and +if a closing parenthesis is needed inside, this one will require to have its +own quotes. + +The keyword argument parser is exactly the same as the top-level one regarding +quotes, except that the \#, \$, and \xNN escapes are not processed. But what is +not always obvious is that the delimiters used inside must first be escaped or +quoted so that they are not resolved at the top level. + +Let's take this example making use of the "regsub" converter which takes 3 +arguments, one regular expression, one replacement string and one set of flags: + + # replace all occurrences of "foo" with "blah" in the path: + http-request set-path %[path,regsub(foo,blah,g)] + +Here no special quoting was necessary. But if now we want to replace either +"foo" or "bar" with "blah", we'll need the regular expression "(foo|bar)". We +cannot write: + + http-request set-path %[path,regsub((foo|bar),blah,g)] + +because we would like the string to cut like this: + + http-request set-path %[path,regsub((foo|bar),blah,g)] + |---------|----|-| + arg1 _/ / / + arg2 __________/ / + arg3 ______________/ + +but actually what is passed is a string between the opening and closing +parenthesis then garbage: + + http-request set-path %[path,regsub((foo|bar),blah,g)] + |--------|--------| + arg1=(foo|bar _/ / + trailing garbage _________/ + +The obvious solution here seems to be that the closing parenthesis needs to be +quoted, but alone this will not work, because as mentioned above, quotes are +processed by the top-level parser which will resolve them before processing +this word: + + http-request set-path %[path,regsub("(foo|bar)",blah,g)] + ------------ -------- ---------------------------------- + word1 word2 word3=%[path,regsub((foo|bar),blah,g)] + +So we didn't change anything for the argument parser at the second level which +still sees a truncated regular expression as the only argument, and garbage at +the end of the string. By escaping the quotes they will be passed unmodified to +the second level: + + http-request set-path %[path,regsub(\"(foo|bar)\",blah,g)] + ------------ -------- ------------------------------------ + word1 word2 word3=%[path,regsub("(foo|bar)",blah,g)] + |---------||----|-| + arg1=(foo|bar) _/ / / + arg2=blah ___________/ / + arg3=g _______________/ + +Another approach consists in using single quotes outside the whole string and +double quotes inside (so that the double quotes are not stripped again): + + http-request set-path '%[path,regsub("(foo|bar)",blah,g)]' + ------------ -------- ---------------------------------- + word1 word2 word3=%[path,regsub("(foo|bar)",blah,g)] + |---------||----|-| + arg1=(foo|bar) _/ / / + arg2 ___________/ / + arg3 _______________/ + +When using regular expressions, it can happen that the dollar ('$') character +appears in the expression or that a backslash ('\') is used in the replacement +string. In this case these ones will also be processed inside the double quotes +thus single quotes are preferred (or double escaping). Example: + + http-request set-path '%[path,regsub("^/(here)(/|$)","my/\1",g)]' + ------------ -------- ----------------------------------------- + word1 word2 word3=%[path,regsub("^/(here)(/|$)","my/\1",g)] + |-------------| |-----||-| + arg1=(here)(/|$) _/ / / + arg2=my/\1 ________________/ / + arg3 ______________________/ + +Remember that backslashes are not escape characters within single quotes and +that the whole word above is already protected against them using the single +quotes. Conversely, if double quotes had been used around the whole expression, +single the dollar character and the backslashes would have been resolved at top +level, breaking the argument contents at the second level. + +Unfortunately, since single quotes can't be escaped inside of strong quoting, +if you need to include single quotes in your argument, you will need to escape +or quote them twice. There are a few ways to do this: + + http-request set-var(txn.foo) str("\\'foo\\'") + http-request set-var(txn.foo) str(\"\'foo\'\") + http-request set-var(txn.foo) str(\\\'foo\\\') + +When in doubt, simply do not use quotes anywhere, and start to place single or +double quotes around arguments that require a comma or a closing parenthesis, +and think about escaping these quotes using a backslash if the string contains +a dollar or a backslash. Again, this is pretty similar to what is used under +a Bourne shell when double-escaping a command passed to "eval". For API writers +the best is probably to place escaped quotes around each and every argument, +regardless of their contents. Users will probably find that using single quotes +around the whole expression and double quotes around each argument provides +more readable configurations. + + +2.3. Environment variables +-------------------------- + +HAProxy's configuration supports environment variables. Those variables are +interpreted only within double quotes. Variables are expanded during the +configuration parsing. Variable names must be preceded by a dollar ("$") and +optionally enclosed with braces ("{}") similarly to what is done in Bourne +shell. Variable names can contain alphanumerical characters or the character +underscore ("_") but should not start with a digit. If the variable contains a +list of several values separated by spaces, it can be expanded as individual +arguments by enclosing the variable with braces and appending the suffix '[*]' +before the closing brace. It is also possible to specify a default value to +use when the variable is not set, by appending that value after a dash '-' +next to the variable name. Note that the default value only replaces non +existing variables, not empty ones. + + Example: + + bind "fd@${FD_APP1}" + + log "${LOCAL_SYSLOG-127.0.0.1}:514" local0 notice # send to local server + + user "$HAPROXY_USER" + +Some variables are defined by HAProxy, they can be used in the configuration +file, or could be inherited by a program (See 3.7. Programs): + +* HAPROXY_LOCALPEER: defined at the startup of the process which contains the + name of the local peer. (See "-L" in the management guide.) + +* HAPROXY_CFGFILES: list of the configuration files loaded by HAProxy, + separated by semicolons. Can be useful in the case you specified a + directory. + +* HAPROXY_MWORKER: In master-worker mode, this variable is set to 1. + +* HAPROXY_CLI: configured listeners addresses of the stats socket for every + processes, separated by semicolons. + +* HAPROXY_MASTER_CLI: In master-worker mode, listeners addresses of the master + CLI, separated by semicolons. + +* HAPROXY_STARTUP_VERSION: contains the version used to start, in master-worker + mode this is the version which was used to start the master, even after + updating the binary and reloading. + +In addition, some pseudo-variables are internally resolved and may be used as +regular variables. Pseudo-variables always start with a dot ('.'), and are the +only ones where the dot is permitted. The current list of pseudo-variables is: + +* .FILE: the name of the configuration file currently being parsed. + +* .LINE: the line number of the configuration file currently being parsed, + starting at one. + +* .SECTION: the name of the section currently being parsed, or its type if the + section doesn't have a name (e.g. "global"), or an empty string before the + first section. + +These variables are resolved at the location where they are parsed. For example +if a ".LINE" variable is used in a "log-format" directive located in a defaults +section, its line number will be resolved before parsing and compiling the +"log-format" directive, so this same line number will be reused by subsequent +proxies. + +This way it is possible to emit information to help locate a rule in variables, +logs, error statuses, health checks, header values, or even to use line numbers +to name some config objects like servers for example. + +See also "external-check command" for other variables. + + +2.4. Conditional blocks +----------------------- + +It may sometimes be convenient to be able to conditionally enable or disable +some arbitrary parts of the configuration, for example to enable/disable SSL or +ciphers, enable or disable some pre-production listeners without modifying the +configuration, or adjust the configuration's syntax to support two distinct +versions of HAProxy during a migration.. HAProxy brings a set of nestable +preprocessor-like directives which allow to integrate or ignore some blocks of +text. These directives must be placed on their own line and they act on the +lines that follow them. Two of them support an expression, the other ones only +switch to an alternate block or end a current level. The 4 following directives +are defined to form conditional blocks: + + - .if <condition> + - .elif <condition> + - .else + - .endif + +The ".if" directive nests a new level, ".elif" stays at the same level, ".else" +as well, and ".endif" closes a level. Each ".if" must be terminated by a +matching ".endif". The ".elif" may only be placed after ".if" or ".elif", and +there is no limit to the number of ".elif" that may be chained. There may be +only one ".else" per ".if" and it must always be after the ".if" or the last +".elif" of a block. + +Comments may be placed on the same line if needed after a '#', they will be +ignored. The directives are tokenized like other configuration directives, and +as such it is possible to use environment variables in conditions. + +Conditions can also be evaluated on startup with the -cc parameter. +See "3. Starting HAProxy" in the management doc. + +The conditions are either an empty string (which then returns false), or an +expression made of any combination of: + + - the integer zero ('0'), always returns "false" + - a non-nul integer (e.g. '1'), always returns "true". + - a predicate optionally followed by argument(s) in parenthesis. + - a condition placed between a pair of parenthesis '(' and ')' + - an exclamation mark ('!') preceding any of the non-empty elements above, + and which will negate its status. + - expressions combined with a logical AND ('&&'), which will be evaluated + from left to right until one returns false + - expressions combined with a logical OR ('||'), which will be evaluated + from right to left until one returns true + +Note that like in other languages, the AND operator has precedence over the OR +operator, so that "A && B || C && D" evalues as "(A && B) || (C && D)". + +The list of currently supported predicates is the following: + + - defined(<name>) : returns true if an environment variable <name> + exists, regardless of its contents + + - feature(<name>) : returns true if feature <name> is listed as present + in the features list reported by "haproxy -vv" + (which means a <name> appears after a '+') + + - streq(<str1>,<str2>) : returns true only if the two strings are equal + - strneq(<str1>,<str2>) : returns true only if the two strings differ + + - version_atleast(<ver>): returns true if the current haproxy version is + at least as recent as <ver> otherwise false. The + version syntax is the same as shown by "haproxy -v" + and missing components are assumed as being zero. + + - version_before(<ver>) : returns true if the current haproxy version is + strictly older than <ver> otherwise false. The + version syntax is the same as shown by "haproxy -v" + and missing components are assumed as being zero. + +Example: + + .if defined(HAPROXY_MWORKER) + listen mwcli_px + bind :1111 + ... + .endif + + .if strneq("$SSL_ONLY",yes) + bind :80 + .endif + + .if streq("$WITH_SSL",yes) + .if feature(OPENSSL) + bind :443 ssl crt ... + .endif + .endif + + .if feature(OPENSSL) && (streq("$WITH_SSL",yes) || streq("$SSL_ONLY",yes)) + bind :443 ssl crt ... + .endif + + .if version_atleast(2.4-dev19) + profiling.memory on + .endif + + .if !feature(OPENSSL) + .alert "SSL support is mandatory" + .endif + +Four other directives are provided to report some status: + + - .diag "message" : emit this message only when in diagnostic mode (-dD) + - .notice "message" : emit this message at level NOTICE + - .warning "message" : emit this message at level WARNING + - .alert "message" : emit this message at level ALERT + +Messages emitted at level WARNING may cause the process to fail to start if the +"strict-mode" is enabled. Messages emitted at level ALERT will always cause a +fatal error. These can be used to detect some inappropriate conditions and +provide advice to the user. + +Example: + + .if "${A}" + .if "${B}" + .notice "A=1, B=1" + .elif "${C}" + .notice "A=1, B=0, C=1" + .elif "${D}" + .warning "A=1, B=0, C=0, D=1" + .else + .alert "A=1, B=0, C=0, D=0" + .endif + .else + .notice "A=0" + .endif + + .diag "WTA/2021-05-07: replace 'redirect' with 'return' after switch to 2.4" + http-request redirect location /goaway if ABUSE + + +2.5. Time format +---------------- + +Some parameters involve values representing time, such as timeouts. These +values are generally expressed in milliseconds (unless explicitly stated +otherwise) but may be expressed in any other unit by suffixing the unit to the +numeric value. It is important to consider this because it will not be repeated +for every keyword. Supported units are : + + - us : microseconds. 1 microsecond = 1/1000000 second + - ms : milliseconds. 1 millisecond = 1/1000 second. This is the default. + - s : seconds. 1s = 1000ms + - m : minutes. 1m = 60s = 60000ms + - h : hours. 1h = 60m = 3600s = 3600000ms + - d : days. 1d = 24h = 1440m = 86400s = 86400000ms + + +2.6. Examples +------------- + + # Simple configuration for an HTTP proxy listening on port 80 on all + # interfaces and forwarding requests to a single backend "servers" with a + # single server "server1" listening on 127.0.0.1:8000 + global + daemon + maxconn 256 + + defaults + mode http + timeout connect 5000ms + timeout client 50000ms + timeout server 50000ms + + frontend http-in + bind *:80 + default_backend servers + + backend servers + server server1 127.0.0.1:8000 maxconn 32 + + + # The same configuration defined with a single listen block. Shorter but + # less expressive, especially in HTTP mode. + global + daemon + maxconn 256 + + defaults + mode http + timeout connect 5000ms + timeout client 50000ms + timeout server 50000ms + + listen http-in + bind *:80 + server server1 127.0.0.1:8000 maxconn 32 + + +Assuming haproxy is in $PATH, test these configurations in a shell with: + + $ sudo haproxy -f configuration.conf -c + + +3. Global parameters +-------------------- + +Parameters in the "global" section are process-wide and often OS-specific. They +are generally set once for all and do not need being changed once correct. Some +of them have command-line equivalents. + +The following keywords are supported in the "global" section : + + * Process management and security + - 51degrees-cache-size + - 51degrees-data-file + - 51degrees-property-name-list + - 51degrees-property-separator + - ca-base + - chroot + - cluster-secret + - cpu-map + - crt-base + - daemon + - default-path + - description + - deviceatlas-json-file + - deviceatlas-log-level + - deviceatlas-properties-cookie + - deviceatlas-separator + - expose-experimental-directives + - external-check + - fd-hard-limit + - gid + - grace + - group + - h1-accept-payload-with-any-method + - h1-case-adjust + - h1-case-adjust-file + - h2-workaround-bogus-websocket-clients + - hard-stop-after + - httpclient.resolvers.id + - httpclient.resolvers.prefer + - httpclient.ssl.ca-file + - httpclient.ssl.verify + - insecure-fork-wanted + - insecure-setuid-wanted + - issuers-chain-path + - localpeer + - log + - log-send-hostname + - log-tag + - lua-load + - lua-load-per-thread + - lua-prepend-path + - mworker-max-reloads + - nbthread + - node + - numa-cpu-mapping + - pidfile + - pp2-never-send-local + - presetenv + - resetenv + - set-dumpable + - set-var + - setenv + - ssl-default-bind-ciphers + - ssl-default-bind-ciphersuites + - ssl-default-bind-curves + - ssl-default-bind-options + - ssl-default-server-ciphers + - ssl-default-server-ciphersuites + - ssl-default-server-options + - ssl-dh-param-file + - ssl-propquery + - ssl-provider + - ssl-provider-path + - ssl-server-verify + - ssl-skip-self-issued-ca + - stats + - strict-limits + - uid + - ulimit-n + - unix-bind + - unsetenv + - user + - wurfl-cache-size + - wurfl-data-file + - wurfl-information-list + - wurfl-information-list-separator + + * Performance tuning + - busy-polling + - max-spread-checks + - maxcompcpuusage + - maxcomprate + - maxconn + - maxconnrate + - maxpipes + - maxsessrate + - maxsslconn + - maxsslrate + - maxzlibmem + - no-memory-trimming + - noepoll + - noevports + - nogetaddrinfo + - nokqueue + - nopoll + - noreuseport + - nosplice + - profiling.tasks + - server-state-base + - server-state-file + - spread-checks + - ssl-engine + - ssl-mode-async + - tune.buffers.limit + - tune.buffers.reserve + - tune.bufsize + - tune.comp.maxlevel + - tune.fail-alloc + - tune.fd.edge-triggered + - tune.h2.header-table-size + - tune.h2.initial-window-size + - tune.h2.max-concurrent-streams + - tune.http.cookielen + - tune.http.logurilen + - tune.http.maxhdr + - tune.idle-pool.shared + - tune.idletimer + - tune.lua.forced-yield + - tune.lua.maxmem + - tune.lua.service-timeout + - tune.lua.session-timeout + - tune.lua.task-timeout + - tune.maxaccept + - tune.maxpollevents + - tune.maxrewrite + - tune.pattern.cache-size + - tune.peers.max-updates-at-once + - tune.pipesize + - tune.pool-high-fd-ratio + - tune.pool-low-fd-ratio + - tune.quic.frontend.conn-tx-buffers.limit + - tune.quic.frontend.max-idle-timeout + - tune.quic.frontend.max-streams-bidi + - tune.quic.retry-threshold + - tune.rcvbuf.client + - tune.rcvbuf.server + - tune.recv_enough + - tune.runqueue-depth + - tune.sched.low-latency + - tune.sndbuf.client + - tune.sndbuf.server + - tune.ssl.cachesize + - tune.ssl.capture-buffer-size + - tune.ssl.capture-cipherlist-size (deprecated) + - tune.ssl.default-dh-param + - tune.ssl.force-private-cache + - tune.ssl.hard-maxrecord + - tune.ssl.keylog + - tune.ssl.lifetime + - tune.ssl.maxrecord + - tune.ssl.ssl-ctx-cache-size + - tune.vars.global-max-size + - tune.vars.proc-max-size + - tune.vars.reqres-max-size + - tune.vars.sess-max-size + - tune.vars.txn-max-size + - tune.zlib.memlevel + - tune.zlib.windowsize + + * Debugging + - quiet + - zero-warning + + +3.1. Process management and security +------------------------------------ + +51degrees-data-file <file path> + The path of the 51Degrees data file to provide device detection services. The + file should be unzipped and accessible by HAProxy with relevant permissions. + + Please note that this option is only available when HAProxy has been + compiled with USE_51DEGREES. + +51degrees-property-name-list [<string> ...] + A list of 51Degrees property names to be load from the dataset. A full list + of names is available on the 51Degrees website: + https://51degrees.com/resources/property-dictionary + + Please note that this option is only available when HAProxy has been + compiled with USE_51DEGREES. + +51degrees-property-separator <char> + A char that will be appended to every property value in a response header + containing 51Degrees results. If not set that will be set as ','. + + Please note that this option is only available when HAProxy has been + compiled with USE_51DEGREES. + +51degrees-cache-size <number> + Sets the size of the 51Degrees converter cache to <number> entries. This + is an LRU cache which reminds previous device detections and their results. + By default, this cache is disabled. + + Please note that this option is only available when HAProxy has been + compiled with USE_51DEGREES. + +ca-base <dir> + Assigns a default directory to fetch SSL CA certificates and CRLs from when a + relative path is used with "ca-file", "ca-verify-file" or "crl-file" + directives. Absolute locations specified in "ca-file", "ca-verify-file" and + "crl-file" prevail and ignore "ca-base". + +chroot <jail dir> + Changes current directory to <jail dir> and performs a chroot() there before + dropping privileges. This increases the security level in case an unknown + vulnerability would be exploited, since it would make it very hard for the + attacker to exploit the system. This only works when the process is started + with superuser privileges. It is important to ensure that <jail_dir> is both + empty and non-writable to anyone. + +close-spread-time <time> + Define a time window during which idle connections and active connections + closing is spread in case of soft-stop. After a SIGUSR1 is received and the + grace period is over (if any), the idle connections will all be closed at + once if this option is not set, and active HTTP or HTTP2 connections will be + ended after the next request is received, either by appending a "Connection: + close" line to the HTTP response, or by sending a GOAWAY frame in case of + HTTP2. When this option is set, connection closing will be spread over this + set <time>. + If the close-spread-time is set to "infinite", active connection closing + during a soft-stop will be disabled. The "Connection: close" header will not + be added to HTTP responses (or GOAWAY for HTTP2) anymore and idle connections + will only be closed once their timeout is reached (based on the various + timeouts set in the configuration). + + Arguments : + <time> is a time window (by default in milliseconds) during which + connection closing will be spread during a soft-stop operation, or + "infinite" if active connection closing should be disabled. + + It is recommended to set this setting to a value lower than the one used in + the "hard-stop-after" option if this one is used, so that all connections + have a chance to gracefully close before the process stops. + + See also: grace, hard-stop-after, idle-close-on-response + +cluster-secret <secret> + Define an ASCII string secret shared between several nodes belonging to the + same cluster. It could be used for different usages. It is at least used to + derive stateless reset tokens for all the QUIC connections instantiated by + this process. This is also the case to derive secrets used to encrypt Retry + tokens. If you do not set this parameter, the stateless reset and Retry QUIC + features will be both silently disabled. + +cpu-map [auto:]<thread-group>[/<thread-set>] <cpu-set>... + On some operating systems, it is possible to bind a thread group or a thread + to a specific CPU set. This means that the designated threads will never run + on other CPUs. The "cpu-map" directive specifies CPU sets for individual + threads or thread groups. The first argument is a thread group range, + optionally followed by a thread set. These ranges have the following format: + + all | odd | even | number[-[number]] + + <number> must be a number between 1 and 32 or 64, depending on the machine's + word size. Any process IDs above 1 and any thread IDs above nbthread are + ignored. It is possible to specify a range with two such number delimited by + a dash ('-'). It also is possible to specify all thraeds at once using + "all", only odd numbers using "odd" or even numbers using "even", just like + with the "bind-process" directive. The second and forthcoming arguments are + CPU sets. Each CPU set is either a unique number starting at 0 for the first + CPU or a range with two such numbers delimited by a dash ('-'). Outside of + Linux and BSDs, there may be a limitation on the maximum CPU index to either + 31 or 63. Multiple CPU numbers or ranges may be specified, and the processes + or threads will be allowed to bind to all of them. Obviously, multiple + "cpu-map" directives may be specified. Each "cpu-map" directive will replace + the previous ones when they overlap. A thread will be bound on the + intersection of its mapping and the one of the process on which it is + attached. If the intersection is null, no specific binding will be set for + the thread. + + Ranges can be partially defined. The higher bound can be omitted. In such + case, it is replaced by the corresponding maximum value, 32 or 64 depending + on the machine's word size. + + The prefix "auto:" can be added before the process set to let HAProxy + automatically bind a process or a thread to a CPU by incrementing threads and + CPU sets. To be valid, both sets must have the same size. No matter the + declaration order of the CPU sets, it will be bound from the lowest to the + highest bound. Having both a process and a thread range with the "auto:" + prefix is not supported. Only one range is supported, the other one must be + a fixed number. + + Note that process ranges are supported for historical reasons. Nowadays, a + lone number designates a process and must be 1, and specifying a thread range + or number requires to prepend "1/" in front of it. Finally, "1" is strictly + equivalent to "1/all" and designates all threads on the process. + + Examples: + cpu-map 1/all 0-3 # bind all threads of the first process on the + # first 4 CPUs + + cpu-map 1/1- 0- # will be replaced by "cpu-map 1/1-64 0-63" + # or "cpu-map 1/1-32 0-31" depending on the machine's + # word size. + + # all these lines bind the thread 1 to the cpu 0, the thread 2 to cpu 1 + # and so on. + cpu-map auto:1/1-4 0-3 + cpu-map auto:1/1-4 0-1 2-3 + cpu-map auto:1/1-4 3 2 1 0 + + # bind each thread to exactly one CPU using all/odd/even keyword + cpu-map auto:1/all 0-63 + cpu-map auto:1/even 0-31 + cpu-map auto:1/odd 32-63 + + # invalid cpu-map because thread and CPU sets have different sizes. + cpu-map auto:1/1-4 0 # invalid + cpu-map auto:1/1 0-3 # invalid + +crt-base <dir> + Assigns a default directory to fetch SSL certificates from when a relative + path is used with "crtfile" or "crt" directives. Absolute locations specified + prevail and ignore "crt-base". + +daemon + Makes the process fork into background. This is the recommended mode of + operation. It is equivalent to the command line "-D" argument. It can be + disabled by the command line "-db" argument. This option is ignored in + systemd mode. + +default-path { current | config | parent | origin <path> } + By default HAProxy loads all files designated by a relative path from the + location the process is started in. In some circumstances it might be + desirable to force all relative paths to start from a different location + just as if the process was started from such locations. This is what this + directive is made for. Technically it will perform a temporary chdir() to + the designated location while processing each configuration file, and will + return to the original directory after processing each file. It takes an + argument indicating the policy to use when loading files whose path does + not start with a slash ('/'): + - "current" indicates that all relative files are to be loaded from the + directory the process is started in ; this is the default. + + - "config" indicates that all relative files should be loaded from the + directory containing the configuration file. More specifically, if the + configuration file contains a slash ('/'), the longest part up to the + last slash is used as the directory to change to, otherwise the current + directory is used. This mode is convenient to bundle maps, errorfiles, + certificates and Lua scripts together as relocatable packages. When + multiple configuration files are loaded, the directory is updated for + each of them. + + - "parent" indicates that all relative files should be loaded from the + parent of the directory containing the configuration file. More + specifically, if the configuration file contains a slash ('/'), ".." + is appended to the longest part up to the last slash is used as the + directory to change to, otherwise the directory is "..". This mode is + convenient to bundle maps, errorfiles, certificates and Lua scripts + together as relocatable packages, but where each part is located in a + different subdirectory (e.g. "config/", "certs/", "maps/", ...). + + - "origin" indicates that all relative files should be loaded from the + designated (mandatory) path. This may be used to ease management of + different HAProxy instances running in parallel on a system, where each + instance uses a different prefix but where the rest of the sections are + made easily relocatable. + + Each "default-path" directive instantly replaces any previous one and will + possibly result in switching to a different directory. While this should + always result in the desired behavior, it is really not a good practice to + use multiple default-path directives, and if used, the policy ought to remain + consistent across all configuration files. + + Warning: some configuration elements such as maps or certificates are + uniquely identified by their configured path. By using a relocatable layout, + it becomes possible for several of them to end up with the same unique name, + making it difficult to update them at run time, especially when multiple + configuration files are loaded from different directories. It is essential to + observe a strict collision-free file naming scheme before adopting relative + paths. A robust approach could consist in prefixing all files names with + their respective site name, or in doing so at the directory level. + +description <text> + Add a text that describes the instance. + + Please note that it is required to escape certain characters (# for example) + and this text is inserted into a html page so you should avoid using + "<" and ">" characters. + +deviceatlas-json-file <path> + Sets the path of the DeviceAtlas JSON data file to be loaded by the API. + The path must be a valid JSON data file and accessible by HAProxy process. + +deviceatlas-log-level <value> + Sets the level of information returned by the API. This directive is + optional and set to 0 by default if not set. + +deviceatlas-properties-cookie <name> + Sets the client cookie's name used for the detection if the DeviceAtlas + Client-side component was used during the request. This directive is optional + and set to DAPROPS by default if not set. + +deviceatlas-separator <char> + Sets the character separator for the API properties results. This directive + is optional and set to | by default if not set. + +expose-experimental-directives + This statement must appear before using directives tagged as experimental or + the config file will be rejected. + +external-check + Allows the use of an external agent to perform health checks. This is + disabled by default as a security precaution, and even when enabled, checks + may still fail unless "insecure-fork-wanted" is enabled as well. If the + program launched makes use of a setuid executable (it should really not), + you may also need to set "insecure-setuid-wanted" in the global section. + See "option external-check", and "insecure-fork-wanted", and + "insecure-setuid-wanted". + +fd-hard-limit <number> + Sets an upper bound to the maximum number of file descriptors that the + process will use, regardless of system limits. While "ulimit-n" and "maxconn" + may be used to enforce a value, when they are not set, the process will be + limited to the hard limit of the RLIMIT_NOFILE setting as reported by + "ulimit -n -H". But some modern operating systems are now allowing extremely + large values here (in the order of 1 billion), which will consume way too + much RAM for regular usage. The fd-hard-limit setting is provided to enforce + a possibly lower bound to this limit. This means that it will always respect + the system-imposed limits when they are below <number> but the specified + value will be used if system-imposed limits are higher. In the example below, + no other setting is specified and the maxconn value will automatically adapt + to the lower of "fd-hard-limit" and the system-imposed limit: + + global + # use as many FDs as possible but no more than 50000 + fd-hard-limit 50000 + + See also: ulimit-n, maxconn + +gid <number> + Changes the process's group ID to <number>. It is recommended that the group + ID is dedicated to HAProxy or to a small set of similar daemons. HAProxy must + be started with a user belonging to this group, or with superuser privileges. + Note that if HAProxy is started from a user having supplementary groups, it + will only be able to drop these groups if started with superuser privileges. + See also "group" and "uid". + +grace <time> + Defines a delay between SIGUSR1 and real soft-stop. + + Arguments : + <time> is an extra delay (by default in milliseconds) after receipt of the + SIGUSR1 signal that will be waited for before proceeding with the + soft-stop operation. + + This is used for compatibility with legacy environments where the haproxy + process needs to be stopped but some external components need to detect the + status before listeners are unbound. The principle is that the internal + "stopping" variable (which is reported by the "stopping" sample fetch + function) will be turned to true, but listeners will continue to accept + connections undisturbed, until the delay expires, after what the regular + soft-stop will proceed. This must not be used with processes that are + reloaded, or this will prevent the old process from unbinding, and may + prevent the new one from starting, or simply cause trouble. + + Example: + + global + grace 10s + + # Returns 200 OK until stopping is set via SIGUSR1 + frontend ext-check + bind :9999 + monitor-uri /ext-check + monitor fail if { stopping } + + Please note that a more flexible and durable approach would instead consist + for an orchestration system in setting a global variable from the CLI, use + that variable to respond to external checks, then after a delay send the + SIGUSR1 signal. + + Example: + + # Returns 200 OK until proc.stopping is set to non-zero. May be done + # from HTTP using set-var(proc.stopping) or from the CLI using: + # > set var proc.stopping int(1) + frontend ext-check + bind :9999 + monitor-uri /ext-check + monitor fail if { var(proc.stopping) -m int gt 0 } + + See also: hard-stop-after, monitor + +group <group name> + Similar to "gid" but uses the GID of group name <group name> from /etc/group. + See also "gid" and "user". + +h1-accept-payload-with-any-method + Does not reject HTTP/1.0 GET/HEAD/DELETE requests with a payload. + + While It is explicitly allowed in HTTP/1.1, HTTP/1.0 is not clear on this + point and some old servers don't expect any payload and never look for body + length (via Content-Length or Transfer-Encoding headers). It means that some + intermediaries may properly handle the payload for HTTP/1.0 GET/HEAD/DELETE + requests, while some others may totally ignore it. That may lead to security + issues because a request smuggling attack is possible. Thus, by default, + HAProxy rejects HTTP/1.0 GET/HEAD/DELETE requests with a payload. + + However, it may be an issue with some old clients. In this case, this global + option may be set. + +h1-case-adjust <from> <to> + Defines the case adjustment to apply, when enabled, to the header name + <from>, to change it to <to> before sending it to HTTP/1 clients or + servers. <from> must be in lower case, and <from> and <to> must not differ + except for their case. It may be repeated if several header names need to be + adjusted. Duplicate entries are not allowed. If a lot of header names have to + be adjusted, it might be more convenient to use "h1-case-adjust-file". + Please note that no transformation will be applied unless "option + h1-case-adjust-bogus-client" or "option h1-case-adjust-bogus-server" is + specified in a proxy. + + There is no standard case for header names because, as stated in RFC7230, + they are case-insensitive. So applications must handle them in a case- + insensitive manner. But some bogus applications violate the standards and + erroneously rely on the cases most commonly used by browsers. This problem + becomes critical with HTTP/2 because all header names must be exchanged in + lower case, and HAProxy follows the same convention. All header names are + sent in lower case to clients and servers, regardless of the HTTP version. + + Applications which fail to properly process requests or responses may require + to temporarily use such workarounds to adjust header names sent to them for + the time it takes the application to be fixed. Please note that an + application which requires such workarounds might be vulnerable to content + smuggling attacks and must absolutely be fixed. + + Example: + global + h1-case-adjust content-length Content-Length + + See "h1-case-adjust-file", "option h1-case-adjust-bogus-client" and + "option h1-case-adjust-bogus-server". + +h1-case-adjust-file <hdrs-file> + Defines a file containing a list of key/value pairs used to adjust the case + of some header names before sending them to HTTP/1 clients or servers. The + file <hdrs-file> must contain 2 header names per line. The first one must be + in lower case and both must not differ except for their case. Lines which + start with '#' are ignored, just like empty lines. Leading and trailing tabs + and spaces are stripped. Duplicate entries are not allowed. Please note that + no transformation will be applied unless "option h1-case-adjust-bogus-client" + or "option h1-case-adjust-bogus-server" is specified in a proxy. + + If this directive is repeated, only the last one will be processed. It is an + alternative to the directive "h1-case-adjust" if a lot of header names need + to be adjusted. Please read the risks associated with using this. + + See "h1-case-adjust", "option h1-case-adjust-bogus-client" and + "option h1-case-adjust-bogus-server". + +h2-workaround-bogus-websocket-clients + This disables the announcement of the support for h2 websockets to clients. + This can be use to overcome clients which have issues when implementing the + relatively fresh RFC8441, such as Firefox 88. To allow clients to + automatically downgrade to http/1.1 for the websocket tunnel, specify h2 + support on the bind line using "alpn" without an explicit "proto" keyword. If + this statement was previously activated, this can be disabled by prefixing + the keyword with "no'. + +hard-stop-after <time> + Defines the maximum time allowed to perform a clean soft-stop. + + Arguments : + <time> is the maximum time (by default in milliseconds) for which the + instance will remain alive when a soft-stop is received via the + SIGUSR1 signal. + + This may be used to ensure that the instance will quit even if connections + remain opened during a soft-stop (for example with long timeouts for a proxy + in tcp mode). It applies both in TCP and HTTP mode. + + Example: + global + hard-stop-after 30s + + See also: grace + +httpclient.resolvers.id <resolvers id> + This option defines the resolvers section with which the httpclient will try + to resolve. + + Default option is the "default" resolvers ID. By default, if this option is + not used, it will simply disable the resolving if the section is not found. + + However, when this option is explicitly enabled it will trigger a + configuration error if it fails to load. + +httpclient.resolvers.prefer <ipv4|ipv6> + This option allows to chose which family of IP you want when resolving, + which is convenient when IPv6 is not available on your network. Default + option is "ipv6". + +httpclient.ssl.ca-file <cafile> + This option defines the ca-file which should be used to verify the server + certificate. It takes the same parameters as the "ca-file" option on the + server line. + + By default and when this option is not used, the value is + "@system-ca" which tries to load the CA of the system. If it fails the SSL + will be disabled for the httpclient. + + However, when this option is explicitly enabled it will trigger a + configuration error if it fails. + +httpclient.ssl.verify [none|required] + Works the same way as the verify option on server lines. If specified to 'none', + servers certificates are not verified. Default option is "required". + + By default and when this option is not used, the value is + "required". If it fails the SSL will be disabled for the httpclient. + + However, when this option is explicitly enabled it will trigger a + configuration error if it fails. + +insecure-fork-wanted + By default HAProxy tries hard to prevent any thread and process creation + after it starts. Doing so is particularly important when using Lua files of + uncertain origin, and when experimenting with development versions which may + still contain bugs whose exploitability is uncertain. And generally speaking + it's good hygiene to make sure that no unexpected background activity can be + triggered by traffic. But this prevents external checks from working, and may + break some very specific Lua scripts which actively rely on the ability to + fork. This option is there to disable this protection. Note that it is a bad + idea to disable it, as a vulnerability in a library or within HAProxy itself + will be easier to exploit once disabled. In addition, forking from Lua or + anywhere else is not reliable as the forked process may randomly embed a lock + set by another thread and never manage to finish an operation. As such it is + highly recommended that this option is never used and that any workload + requiring such a fork be reconsidered and moved to a safer solution (such as + agents instead of external checks). This option supports the "no" prefix to + disable it. + +insecure-setuid-wanted + HAProxy doesn't need to call executables at run time (except when using + external checks which are strongly recommended against), and is even expected + to isolate itself into an empty chroot. As such, there basically is no valid + reason to allow a setuid executable to be called without the user being fully + aware of the risks. In a situation where HAProxy would need to call external + checks and/or disable chroot, exploiting a vulnerability in a library or in + HAProxy itself could lead to the execution of an external program. On Linux + it is possible to lock the process so that any setuid bit present on such an + executable is ignored. This significantly reduces the risk of privilege + escalation in such a situation. This is what HAProxy does by default. In case + this causes a problem to an external check (for example one which would need + the "ping" command), then it is possible to disable this protection by + explicitly adding this directive in the global section. If enabled, it is + possible to turn it back off by prefixing it with the "no" keyword. + +issuers-chain-path <dir> + Assigns a directory to load certificate chain for issuer completion. All + files must be in PEM format. For certificates loaded with "crt" or "crt-list", + if certificate chain is not included in PEM (also commonly known as + intermediate certificate), HAProxy will complete chain if the issuer of the + certificate corresponds to the first certificate of the chain loaded with + "issuers-chain-path". + A "crt" file with PrivateKey+Certificate+IntermediateCA2+IntermediateCA1 + could be replaced with PrivateKey+Certificate. HAProxy will complete the + chain if a file with IntermediateCA2+IntermediateCA1 is present in + "issuers-chain-path" directory. All other certificates with the same issuer + will share the chain in memory. + +localpeer <name> + Sets the local instance's peer name. It will be ignored if the "-L" + command line argument is specified or if used after "peers" section + definitions. In such cases, a warning message will be emitted during + the configuration parsing. + + This option will also set the HAPROXY_LOCALPEER environment variable. + See also "-L" in the management guide and "peers" section below. + +log <address> [len <length>] [format <format>] [sample <ranges>:<sample_size>] + <facility> [max level [min level]] + Adds a global syslog server. Several global servers can be defined. They + will receive logs for starts and exits, as well as all logs from proxies + configured with "log global". + + <address> can be one of: + + - An IPv4 address optionally followed by a colon and a UDP port. If + no port is specified, 514 is used by default (the standard syslog + port). + + - An IPv6 address followed by a colon and optionally a UDP port. If + no port is specified, 514 is used by default (the standard syslog + port). + + - A filesystem path to a datagram UNIX domain socket, keeping in mind + considerations for chroot (be sure the path is accessible inside + the chroot) and uid/gid (be sure the path is appropriately + writable). + + - A file descriptor number in the form "fd@<number>", which may point + to a pipe, terminal, or socket. In this case unbuffered logs are used + and one writev() call per log is performed. This is a bit expensive + but acceptable for most workloads. Messages sent this way will not be + truncated but may be dropped, in which case the DroppedLogs counter + will be incremented. The writev() call is atomic even on pipes for + messages up to PIPE_BUF size, which POSIX recommends to be at least + 512 and which is 4096 bytes on most modern operating systems. Any + larger message may be interleaved with messages from other processes. + Exceptionally for debugging purposes the file descriptor may also be + directed to a file, but doing so will significantly slow HAProxy down + as non-blocking calls will be ignored. Also there will be no way to + purge nor rotate this file without restarting the process. Note that + the configured syslog format is preserved, so the output is suitable + for use with a TCP syslog server. See also the "short" and "raw" + format below. + + - "stdout" / "stderr", which are respectively aliases for "fd@1" and + "fd@2", see above. + + - A ring buffer in the form "ring@<name>", which will correspond to an + in-memory ring buffer accessible over the CLI using the "show events" + command, which will also list existing rings and their sizes. Such + buffers are lost on reload or restart but when used as a complement + this can help troubleshooting by having the logs instantly available. + + You may want to reference some environment variables in the address + parameter, see section 2.3 about environment variables. + + <length> is an optional maximum line length. Log lines larger than this value + will be truncated before being sent. The reason is that syslog + servers act differently on log line length. All servers support the + default value of 1024, but some servers simply drop larger lines + while others do log them. If a server supports long lines, it may + make sense to set this value here in order to avoid truncating long + lines. Similarly, if a server drops long lines, it is preferable to + truncate them before sending them. Accepted values are 80 to 65535 + inclusive. The default value of 1024 is generally fine for all + standard usages. Some specific cases of long captures or + JSON-formatted logs may require larger values. You may also need to + increase "tune.http.logurilen" if your request URIs are truncated. + + <format> is the log format used when generating syslog messages. It may be + one of the following : + + local Analog to rfc3164 syslog message format except that hostname + field is stripped. This is the default. + Note: option "log-send-hostname" switches the default to + rfc3164. + + rfc3164 The RFC3164 syslog message format. + (https://tools.ietf.org/html/rfc3164) + + rfc5424 The RFC5424 syslog message format. + (https://tools.ietf.org/html/rfc5424) + + priority A message containing only a level plus syslog facility between + angle brackets such as '<63>', followed by the text. The PID, + date, time, process name and system name are omitted. This is + designed to be used with a local log server. + + short A message containing only a level between angle brackets such as + '<3>', followed by the text. The PID, date, time, process name + and system name are omitted. This is designed to be used with a + local log server. This format is compatible with what the systemd + logger consumes. + + timed A message containing only a level between angle brackets such as + '<3>', followed by ISO date and by the text. The PID, process + name and system name are omitted. This is designed to be + used with a local log server. + + iso A message containing only the ISO date, followed by the text. + The PID, process name and system name are omitted. This is + designed to be used with a local log server. + + raw A message containing only the text. The level, PID, date, time, + process name and system name are omitted. This is designed to be + used in containers or during development, where the severity only + depends on the file descriptor used (stdout/stderr). + + <ranges> A list of comma-separated ranges to identify the logs to sample. + This is used to balance the load of the logs to send to the log + server. The limits of the ranges cannot be null. They are numbered + from 1. The size or period (in number of logs) of the sample must be + set with <sample_size> parameter. + + <sample_size> + The size of the sample in number of logs to consider when balancing + their logging loads. It is used to balance the load of the logs to + send to the syslog server. This size must be greater or equal to the + maximum of the high limits of the ranges. + (see also <ranges> parameter). + + <facility> must be one of the 24 standard syslog facilities : + + kern user mail daemon auth syslog lpr news + uucp cron auth2 ftp ntp audit alert cron2 + local0 local1 local2 local3 local4 local5 local6 local7 + + Note that the facility is ignored for the "short" and "raw" + formats, but still required as a positional field. It is + recommended to use "daemon" in this case to make it clear that + it's only supposed to be used locally. + + An optional level can be specified to filter outgoing messages. By default, + all messages are sent. If a maximum level is specified, only messages with a + severity at least as important as this level will be sent. An optional minimum + level can be specified. If it is set, logs emitted with a more severe level + than this one will be capped to this level. This is used to avoid sending + "emerg" messages on all terminals on some default syslog configurations. + Eight levels are known : + + emerg alert crit err warning notice info debug + +log-send-hostname [<string>] + Sets the hostname field in the syslog header. If optional "string" parameter + is set the header is set to the string contents, otherwise uses the hostname + of the system. Generally used if one is not relaying logs through an + intermediate syslog server or for simply customizing the hostname printed in + the logs. + +log-tag <string> + Sets the tag field in the syslog header to this string. It defaults to the + program name as launched from the command line, which usually is "haproxy". + Sometimes it can be useful to differentiate between multiple processes + running on the same host. See also the per-proxy "log-tag" directive. + +lua-load <file> + This global directive loads and executes a Lua file in the shared context + that is visible to all threads. Any variable set in such a context is visible + from any thread. This is the easiest and recommended way to load Lua programs + but it will not scale well if a lot of Lua calls are performed, as only one + thread may be running on the global state at a time. A program loaded this + way will always see 0 in the "core.thread" variable. This directive can be + used multiple times. + +lua-load-per-thread <file> + This global directive loads and executes a Lua file into each started thread. + Any global variable has a thread-local visibility so that each thread could + see a different value. As such it is strongly recommended not to use global + variables in programs loaded this way. An independent copy is loaded and + initialized for each thread, everything is done sequentially and in the + thread's numeric order from 1 to nbthread. If some operations need to be + performed only once, the program should check the "core.thread" variable to + figure what thread is being initialized. Programs loaded this way will run + concurrently on all threads and will be highly scalable. This is the + recommended way to load simple functions that register sample-fetches, + converters, actions or services once it is certain the program doesn't depend + on global variables. For the sake of simplicity, the directive is available + even if only one thread is used and even if threads are disabled (in which + case it will be equivalent to lua-load). This directive can be used multiple + times. + +lua-prepend-path <string> [<type>] + Prepends the given string followed by a semicolon to Lua's package.<type> + variable. + <type> must either be "path" or "cpath". If <type> is not given it defaults + to "path". + + Lua's paths are semicolon delimited lists of patterns that specify how the + `require` function attempts to find the source file of a library. Question + marks (?) within a pattern will be replaced by module name. The path is + evaluated left to right. This implies that paths that are prepended later + will be checked earlier. + + As an example by specifying the following path: + + lua-prepend-path /usr/share/haproxy-lua/?/init.lua + lua-prepend-path /usr/share/haproxy-lua/?.lua + + When `require "example"` is being called Lua will first attempt to load the + /usr/share/haproxy-lua/example.lua script, if that does not exist the + /usr/share/haproxy-lua/example/init.lua will be attempted and the default + paths if that does not exist either. + + See https://www.lua.org/pil/8.1.html for the details within the Lua + documentation. + +master-worker [no-exit-on-failure] + Master-worker mode. It is equivalent to the command line "-W" argument. + This mode will launch a "master" which will monitor the "workers". Using + this mode, you can reload HAProxy directly by sending a SIGUSR2 signal to + the master. The master-worker mode is compatible either with the foreground + or daemon mode. + + By default, if a worker exits with a bad return code, in the case of a + segfault for example, all workers will be killed, and the master will leave. + It is convenient to combine this behavior with Restart=on-failure in a + systemd unit file in order to relaunch the whole process. If you don't want + this behavior, you must use the keyword "no-exit-on-failure". + + See also "-W" in the management guide. + +mworker-max-reloads <number> + In master-worker mode, this option limits the number of time a worker can + survive to a reload. If the worker did not leave after a reload, once its + number of reloads is greater than this number, the worker will receive a + SIGTERM. This option helps to keep under control the number of workers. + See also "show proc" in the Management Guide. + +nbthread <number> + This setting is only available when support for threads was built in. It + makes HAProxy run on <number> threads. "nbthread" also works when HAProxy is + started in foreground. On some platforms supporting CPU affinity, the default + "nbthread" value is automatically set to the number of CPUs the process is + bound to upon startup. This means that the thread count can easily be + adjusted from the calling process using commands like "taskset" or "cpuset". + Otherwise, this value defaults to 1. The default value is reported in the + output of "haproxy -vv". + +numa-cpu-mapping + If running on a NUMA-aware platform, HAProxy inspects on startup the CPU + topology of the machine. If a multi-socket machine is detected, the affinity + is automatically calculated to run on the CPUs of a single node. This is done + in order to not suffer from the performance penalties caused by the + inter-socket bus latency. However, if the applied binding is non optimal on a + particular architecture, it can be disabled with the statement 'no + numa-cpu-mapping'. This automatic binding is also not applied if a nbthread + statement is present in the configuration, or the affinity of the process is + already specified, for example via the 'cpu-map' directive or the taskset + utility. + +pidfile <pidfile> + Writes PIDs of all daemons into file <pidfile> when daemon mode or writes PID + of master process into file <pidfile> when master-worker mode. This option is + equivalent to the "-p" command line argument. The file must be accessible to + the user starting the process. See also "daemon" and "master-worker". + +pp2-never-send-local + A bug in the PROXY protocol v2 implementation was present in HAProxy up to + version 2.1, causing it to emit a PROXY command instead of a LOCAL command + for health checks. This is particularly minor but confuses some servers' + logs. Sadly, the bug was discovered very late and revealed that some servers + which possibly only tested their PROXY protocol implementation against + HAProxy fail to properly handle the LOCAL command, and permanently remain in + the "down" state when HAProxy checks them. When this happens, it is possible + to enable this global option to revert to the older (bogus) behavior for the + time it takes to contact the affected components' vendors and get them fixed. + This option is disabled by default and acts on all servers having the + "send-proxy-v2" statement. + +presetenv <name> <value> + Sets environment variable <name> to value <value>. If the variable exists, it + is NOT overwritten. The changes immediately take effect so that the next line + in the configuration file sees the new value. See also "setenv", "resetenv", + and "unsetenv". + +resetenv [<name> ...] + Removes all environment variables except the ones specified in argument. It + allows to use a clean controlled environment before setting new values with + setenv or unsetenv. Please note that some internal functions may make use of + some environment variables, such as time manipulation functions, but also + OpenSSL or even external checks. This must be used with extreme care and only + after complete validation. The changes immediately take effect so that the + next line in the configuration file sees the new environment. See also + "setenv", "presetenv", and "unsetenv". + +stats bind-process [ all | odd | even | <process_num>[-[process_num>]] ] ... + Deprecated. Before threads were supported, this was used to force some stats + instances on certain processes only. The default and only accepted value is + "1" (along with "all" and "odd" which alias it). Do not use this setting. + +server-state-base <directory> + Specifies the directory prefix to be prepended in front of all servers state + file names which do not start with a '/'. See also "server-state-file", + "load-server-state-from-file" and "server-state-file-name". + +server-state-file <file> + Specifies the path to the file containing state of servers. If the path starts + with a slash ('/'), it is considered absolute, otherwise it is considered + relative to the directory specified using "server-state-base" (if set) or to + the current directory. Before reloading HAProxy, it is possible to save the + servers' current state using the stats command "show servers state". The + output of this command must be written in the file pointed by <file>. When + starting up, before handling traffic, HAProxy will read, load and apply state + for each server found in the file and available in its current running + configuration. See also "server-state-base" and "show servers state", + "load-server-state-from-file" and "server-state-file-name" + +set-dumpable + This option is better left disabled by default and enabled only upon a + developer's request. If it has been enabled, it may still be forcibly + disabled by prefixing it with the "no" keyword. It has no impact on + performance nor stability but will try hard to re-enable core dumps that were + possibly disabled by file size limitations (ulimit -f), core size limitations + (ulimit -c), or "dumpability" of a process after changing its UID/GID (such + as /proc/sys/fs/suid_dumpable on Linux). Core dumps might still be limited by + the current directory's permissions (check what directory the file is started + from), the chroot directory's permission (it may be needed to temporarily + disable the chroot directive or to move it to a dedicated writable location), + or any other system-specific constraint. For example, some Linux flavours are + notorious for replacing the default core file with a path to an executable + not even installed on the system (check /proc/sys/kernel/core_pattern). Often, + simply writing "core", "core.%p" or "/var/log/core/core.%p" addresses the + issue. When trying to enable this option waiting for a rare issue to + re-appear, it's often a good idea to first try to obtain such a dump by + issuing, for example, "kill -11" to the "haproxy" process and verify that it + leaves a core where expected when dying. + +set-var <var-name> <expr> + Sets the process-wide variable '<var-name>' to the result of the evaluation + of the sample expression <expr>. The variable '<var-name>' may only be a + process-wide variable (using the 'proc.' prefix). It works exactly like the + 'set-var' action in TCP or HTTP rules except that the expression is evaluated + at configuration parsing time and that the variable is instantly set. The + sample fetch functions and converters permitted in the expression are only + those using internal data, typically 'int(value)' or 'str(value)'. It is + possible to reference previously allocated variables as well. These variables + will then be readable (and modifiable) from the regular rule sets. + + Example: + global + set-var proc.current_state str(primary) + set-var proc.prio int(100) + set-var proc.threshold int(200),sub(proc.prio) + +set-var-fmt <var-name> <fmt> + Sets the process-wide variable '<var-name>' to the string resulting from the + evaluation of the log-format <fmt>. The variable '<var-name>' may only be a + process-wide variable (using the 'proc.' prefix). It works exactly like the + 'set-var-fmt' action in TCP or HTTP rules except that the expression is + evaluated at configuration parsing time and that the variable is instantly + set. The sample fetch functions and converters permitted in the expression + are only those using internal data, typically 'int(value)' or 'str(value)'. + It is possible to reference previously allocated variables as well. These + variables will then be readable (and modifiable) from the regular rule sets. + Please see section 8.2.4 for details on the log-format syntax. + + Example: + global + set-var-fmt proc.current_state "primary" + set-var-fmt proc.bootid "%pid|%t" + +setenv <name> <value> + Sets environment variable <name> to value <value>. If the variable exists, it + is overwritten. The changes immediately take effect so that the next line in + the configuration file sees the new value. See also "presetenv", "resetenv", + and "unsetenv". + +ssl-default-bind-ciphers <ciphers> + This setting is only available when support for OpenSSL was built in. It sets + the default string describing the list of cipher algorithms ("cipher suite") + that are negotiated during the SSL/TLS handshake up to TLSv1.2 for all + "bind" lines which do not explicitly define theirs. The format of the string + is defined in "man 1 ciphers" from OpenSSL man pages. For background + information and recommendations see e.g. + (https://wiki.mozilla.org/Security/Server_Side_TLS) and + (https://mozilla.github.io/server-side-tls/ssl-config-generator/). For TLSv1.3 + cipher configuration, please check the "ssl-default-bind-ciphersuites" keyword. + Please check the "bind" keyword for more information. + +ssl-default-bind-ciphersuites <ciphersuites> + This setting is only available when support for OpenSSL was built in and + OpenSSL 1.1.1 or later was used to build HAProxy. It sets the default string + describing the list of cipher algorithms ("cipher suite") that are negotiated + during the TLSv1.3 handshake for all "bind" lines which do not explicitly define + theirs. The format of the string is defined in + "man 1 ciphers" from OpenSSL man pages under the section "ciphersuites". For + cipher configuration for TLSv1.2 and earlier, please check the + "ssl-default-bind-ciphers" keyword. Please check the "bind" keyword for more + information. + +ssl-default-bind-curves <curves> + This setting is only available when support for OpenSSL was built in. It sets + the default string describing the list of elliptic curves algorithms ("curve + suite") that are negotiated during the SSL/TLS handshake with ECDHE. The format + of the string is a colon-delimited list of curve name. + Please check the "bind" keyword for more information. + +ssl-default-bind-options [<option>]... + This setting is only available when support for OpenSSL was built in. It sets + default ssl-options to force on all "bind" lines. Please check the "bind" + keyword to see available options. + + Example: + global + ssl-default-bind-options ssl-min-ver TLSv1.0 no-tls-tickets + +ssl-default-server-ciphers <ciphers> + This setting is only available when support for OpenSSL was built in. It + sets the default string describing the list of cipher algorithms that are + negotiated during the SSL/TLS handshake up to TLSv1.2 with the server, + for all "server" lines which do not explicitly define theirs. The format of + the string is defined in "man 1 ciphers" from OpenSSL man pages. For background + information and recommendations see e.g. + (https://wiki.mozilla.org/Security/Server_Side_TLS) and + (https://mozilla.github.io/server-side-tls/ssl-config-generator/). + For TLSv1.3 cipher configuration, please check the + "ssl-default-server-ciphersuites" keyword. Please check the "server" keyword + for more information. + +ssl-default-server-ciphersuites <ciphersuites> + This setting is only available when support for OpenSSL was built in and + OpenSSL 1.1.1 or later was used to build HAProxy. It sets the default + string describing the list of cipher algorithms that are negotiated during + the TLSv1.3 handshake with the server, for all "server" lines which do not + explicitly define theirs. The format of the string is defined in + "man 1 ciphers" from OpenSSL man pages under the section "ciphersuites". For + cipher configuration for TLSv1.2 and earlier, please check the + "ssl-default-server-ciphers" keyword. Please check the "server" keyword for + more information. + +ssl-default-server-options [<option>]... + This setting is only available when support for OpenSSL was built in. It sets + default ssl-options to force on all "server" lines. Please check the "server" + keyword to see available options. + +ssl-dh-param-file <file> + This setting is only available when support for OpenSSL was built in. It sets + the default DH parameters that are used during the SSL/TLS handshake when + ephemeral Diffie-Hellman (DHE) key exchange is used, for all "bind" lines + which do not explicitly define theirs. It will be overridden by custom DH + parameters found in a bind certificate file if any. If custom DH parameters + are not specified either by using ssl-dh-param-file or by setting them + directly in the certificate file, DHE ciphers will not be used, unless + tune.ssl.default-dh-param is set. In this latter case, pre-defined DH + parameters of the specified size will be used. Custom parameters are known to + be more secure and therefore their use is recommended. + Custom DH parameters may be generated by using the OpenSSL command + "openssl dhparam <size>", where size should be at least 2048, as 1024-bit DH + parameters should not be considered secure anymore. + +ssl-propquery <query> + This setting is only available when support for OpenSSL was built in and when + OpenSSL's version is at least 3.0. It allows to define a default property + string used when fetching algorithms in providers. It behave the same way as + the openssl propquery option and it follows the same syntax (described in + https://www.openssl.org/docs/man3.0/man7/property.html). For instance, if you + have two providers loaded, the foo one and the default one, the propquery + "?provider=foo" allows to pick the algorithm implementations provided by the + foo provider by default, and to fallback on the default provider's one if it + was not found. + +ssl-provider <name> + This setting is only available when support for OpenSSL was built in and when + OpenSSL's version is at least 3.0. It allows to load a provider during init. + If loading is successful, any capabilities provided by the loaded provider + might be used by HAProxy. Multiple 'ssl-provider' options can be specified in + a configuration file. The providers will be loaded in their order of + appearance. + + Please note that loading a provider explicitly prevents OpenSSL from loading + the 'default' provider automatically. OpenSSL also allows to define the + providers that should be loaded directly in its configuration file + (openssl.cnf for instance) so it is not necessary to use this 'ssl-provider' + option to load providers. The "show ssl providers" CLI command can be used to + show all the providers that were successfully loaded. + + The default search path of OpenSSL provider can be found in the output of the + "openssl version -a" command. If the provider is in another directory, you + can set the OPENSSL_MODULES environment variable, which takes the directory + where your provider can be found. + + See also "ssl-propquery" and "ssl-provider-path". + +ssl-provider-path <path> + This setting is only available when support for OpenSSL was built in and when + OpenSSL's version is at least 3.0. It allows to specify the search path that + is to be used by OpenSSL for looking for providers. It behaves the same way + as the OPENSSL_MODULES environment variable. It will be used for any + following 'ssl-provider' option or until a new 'ssl-provider-path' is + defined. + See also "ssl-provider". + +ssl-load-extra-del-ext + This setting allows to configure the way HAProxy does the lookup for the + extra SSL files. By default HAProxy adds a new extension to the filename. + (ex: with "foobar.crt" load "foobar.crt.key"). With this option enabled, + HAProxy removes the extension before adding the new one (ex: with + "foobar.crt" load "foobar.key"). + + Your crt file must have a ".crt" extension for this option to work. + + This option is not compatible with bundle extensions (.ecdsa, .rsa. .dsa) + and won't try to remove them. + + This option is disabled by default. See also "ssl-load-extra-files". + +ssl-load-extra-files <none|all|bundle|sctl|ocsp|issuer|key>* + This setting alters the way HAProxy will look for unspecified files during + the loading of the SSL certificates. This option applies to certificates + associated to "bind" lines as well as "server" lines but some of the extra + files will not have any functional impact for "server" line certificates. + + By default, HAProxy discovers automatically a lot of files not specified in + the configuration, and you may want to disable this behavior if you want to + optimize the startup time. + + "none": Only load the files specified in the configuration. Don't try to load + a certificate bundle if the file does not exist. In the case of a directory, + it won't try to bundle the certificates if they have the same basename. + + "all": This is the default behavior, it will try to load everything, + bundles, sctl, ocsp, issuer, key. + + "bundle": When a file specified in the configuration does not exist, HAProxy + will try to load a "cert bundle". Certificate bundles are only managed on the + frontend side and will not work for backend certificates. + + Starting from HAProxy 2.3, the bundles are not loaded in the same OpenSSL + certificate store, instead it will loads each certificate in a separate + store which is equivalent to declaring multiple "crt". OpenSSL 1.1.1 is + required to achieve this. Which means that bundles are now used only for + backward compatibility and are not mandatory anymore to do an hybrid RSA/ECC + bind configuration. + + To associate these PEM files into a "cert bundle" that is recognized by + HAProxy, they must be named in the following way: All PEM files that are to + be bundled must have the same base name, with a suffix indicating the key + type. Currently, three suffixes are supported: rsa, dsa and ecdsa. For + example, if www.example.com has two PEM files, an RSA file and an ECDSA + file, they must be named: "example.pem.rsa" and "example.pem.ecdsa". The + first part of the filename is arbitrary; only the suffix matters. To load + this bundle into HAProxy, specify the base name only: + + Example : bind :8443 ssl crt example.pem + + Note that the suffix is not given to HAProxy; this tells HAProxy to look for + a cert bundle. + + HAProxy will load all PEM files in the bundle as if they were configured + separately in several "crt". + + The bundle loading does not have an impact anymore on the directory loading + since files are loading separately. + + On the CLI, bundles are seen as separate files, and the bundle extension is + required to commit them. + + OCSP files (.ocsp), issuer files (.issuer), Certificate Transparency (.sctl) + as well as private keys (.key) are supported with multi-cert bundling. + + "sctl": Try to load "<basename>.sctl" for each crt keyword. If provided for + a backend certificate, it will be loaded but will not have any functional + impact. + + "ocsp": Try to load "<basename>.ocsp" for each crt keyword. If provided for + a backend certificate, it will be loaded but will not have any functional + impact. + + "issuer": Try to load "<basename>.issuer" if the issuer of the OCSP file is + not provided in the PEM file. If provided for a backend certificate, it will + be loaded but will not have any functional impact. + + "key": If the private key was not provided by the PEM file, try to load a + file "<basename>.key" containing a private key. + + The default behavior is "all". + + Example: + ssl-load-extra-files bundle sctl + ssl-load-extra-files sctl ocsp issuer + ssl-load-extra-files none + + See also: "crt", section 5.1 about bind options and section 5.2 about server + options. + +ssl-server-verify [none|required] + The default behavior for SSL verify on servers side. If specified to 'none', + servers certificates are not verified. The default is 'required' except if + forced using cmdline option '-dV'. + +ssl-skip-self-issued-ca + Self issued CA, aka x509 root CA, is the anchor for chain validation: as a + server is useless to send it, client must have it. Standard configuration + need to not include such CA in PEM file. This option allows you to keep such + CA in PEM file without sending it to the client. Use case is to provide + issuer for ocsp without the need for '.issuer' file and be able to share it + with 'issuers-chain-path'. This concerns all certificates without intermediate + certificates. It's useless for BoringSSL, .issuer is ignored because ocsp + bits does not need it. Requires at least OpenSSL 1.0.2. + +stats maxconn <connections> + By default, the stats socket is limited to 10 concurrent connections. It is + possible to change this value with "stats maxconn". + +stats socket [<address:port>|<path>] [param*] + Binds a UNIX socket to <path> or a TCPv4/v6 address to <address:port>. + Connections to this socket will return various statistics outputs and even + allow some commands to be issued to change some runtime settings. Please + consult section 9.3 "Unix Socket commands" of Management Guide for more + details. + + All parameters supported by "bind" lines are supported, for instance to + restrict access to some users or their access rights. Please consult + section 5.1 for more information. + +stats timeout <timeout, in milliseconds> + The default timeout on the stats socket is set to 10 seconds. It is possible + to change this value with "stats timeout". The value must be passed in + milliseconds, or be suffixed by a time unit among { us, ms, s, m, h, d }. + +strict-limits + Makes process fail at startup when a setrlimit fails. HAProxy tries to set the + best setrlimit according to what has been calculated. If it fails, it will + emit a warning. This option is here to guarantee an explicit failure of + HAProxy when those limits fail. It is enabled by default. It may still be + forcibly disabled by prefixing it with the "no" keyword. + +thread-group <group> [<thread-range>...] + This setting is only available when support for threads was built in. It + enumerates the list of threads that will compose thread group <group>. + Thread numbers and group numbers start at 1. Thread ranges are defined either + using a single thread number at once, or by specifying the lower and upper + bounds delimited by a dash '-' (e.g. "1-16"). Unassigned threads will be + automatically assigned to unassigned thread groups, and thread groups + defined with this directive will never receive more threads than those + defined. Defining the same group multiple times overrides previous + definitions with the new one. See also "nbthread" and "thread-groups". + +thread-groups <number> + This setting is only available when support for threads was built in. It + makes HAProxy split its threads into <number> independent groups. At the + moment, the limit is 1 and is also the default value. See also "nbthread". + +uid <number> + Changes the process's user ID to <number>. It is recommended that the user ID + is dedicated to HAProxy or to a small set of similar daemons. HAProxy must + be started with superuser privileges in order to be able to switch to another + one. See also "gid" and "user". + +ulimit-n <number> + Sets the maximum number of per-process file-descriptors to <number>. By + default, it is automatically computed, so it is recommended not to use this + option. If the intent is only to limit the number of file descriptors, better + use "fd-hard-limit" instead. + + Note that the dynamic servers are not taken into account in this automatic + resource calculation. If using a large number of them, it may be needed to + manually specify this value. + + See also: fd-hard-limit, maxconn + +unix-bind [ prefix <prefix> ] [ mode <mode> ] [ user <user> ] [ uid <uid> ] + [ group <group> ] [ gid <gid> ] + + Fixes common settings to UNIX listening sockets declared in "bind" statements. + This is mainly used to simplify declaration of those UNIX sockets and reduce + the risk of errors, since those settings are most commonly required but are + also process-specific. The <prefix> setting can be used to force all socket + path to be relative to that directory. This might be needed to access another + component's chroot. Note that those paths are resolved before HAProxy chroots + itself, so they are absolute. The <mode>, <user>, <uid>, <group> and <gid> + all have the same meaning as their homonyms used by the "bind" statement. If + both are specified, the "bind" statement has priority, meaning that the + "unix-bind" settings may be seen as process-wide default settings. + +unsetenv [<name> ...] + Removes environment variables specified in arguments. This can be useful to + hide some sensitive information that are occasionally inherited from the + user's environment during some operations. Variables which did not exist are + silently ignored so that after the operation, it is certain that none of + these variables remain. The changes immediately take effect so that the next + line in the configuration file will not see these variables. See also + "setenv", "presetenv", and "resetenv". + +user <user name> + Similar to "uid" but uses the UID of user name <user name> from /etc/passwd. + See also "uid" and "group". + +node <name> + Only letters, digits, hyphen and underscore are allowed, like in DNS names. + + This statement is useful in HA configurations where two or more processes or + servers share the same IP address. By setting a different node-name on all + nodes, it becomes easy to immediately spot what server is handling the + traffic. + +wurfl-cache-size <size> + Sets the WURFL Useragent cache size. For faster lookups, already processed user + agents are kept in a LRU cache : + - "0" : no cache is used. + - <size> : size of lru cache in elements. + + Please note that this option is only available when HAProxy has been compiled + with USE_WURFL=1. + +wurfl-data-file <file path> + The path of the WURFL data file to provide device detection services. The + file should be accessible by HAProxy with relevant permissions. + + Please note that this option is only available when HAProxy has been compiled + with USE_WURFL=1. + +wurfl-information-list [<capability>]* + A space-delimited list of WURFL capabilities, virtual capabilities, property + names we plan to use in injected headers. A full list of capability and + virtual capability names is available on the Scientiamobile website : + + https://www.scientiamobile.com/wurflCapability + + Valid WURFL properties are: + - wurfl_id Contains the device ID of the matched device. + + - wurfl_root_id Contains the device root ID of the matched + device. + + - wurfl_isdevroot Tells if the matched device is a root device. + Possible values are "TRUE" or "FALSE". + + - wurfl_useragent The original useragent coming with this + particular web request. + + - wurfl_api_version Contains a string representing the currently + used Libwurfl API version. + + - wurfl_info A string containing information on the parsed + wurfl.xml and its full path. + + - wurfl_last_load_time Contains the UNIX timestamp of the last time + WURFL has been loaded successfully. + + - wurfl_normalized_useragent The normalized useragent. + + Please note that this option is only available when HAProxy has been compiled + with USE_WURFL=1. + +wurfl-information-list-separator <char> + A char that will be used to separate values in a response header containing + WURFL results. If not set that a comma (',') will be used by default. + + Please note that this option is only available when HAProxy has been compiled + with USE_WURFL=1. + +wurfl-patch-file [<file path>] + A list of WURFL patch file paths. Note that patches are loaded during startup + thus before the chroot. + + Please note that this option is only available when HAProxy has been compiled + with USE_WURFL=1. + +3.2. Performance tuning +----------------------- + +busy-polling + In some situations, especially when dealing with low latency on processors + supporting a variable frequency or when running inside virtual machines, each + time the process waits for an I/O using the poller, the processor goes back + to sleep or is offered to another VM for a long time, and it causes + excessively high latencies. This option provides a solution preventing the + processor from sleeping by always using a null timeout on the pollers. This + results in a significant latency reduction (30 to 100 microseconds observed) + at the expense of a risk to overheat the processor. It may even be used with + threads, in which case improperly bound threads may heavily conflict, + resulting in a worse performance and high values for the CPU stolen fields + in "show info" output, indicating which threads are misconfigured. It is + important not to let the process run on the same processor as the network + interrupts when this option is used. It is also better to avoid using it on + multiple CPU threads sharing the same core. This option is disabled by + default. If it has been enabled, it may still be forcibly disabled by + prefixing it with the "no" keyword. It is ignored by the "select" and + "poll" pollers. + + This option is automatically disabled on old processes in the context of + seamless reload; it avoids too much cpu conflicts when multiple processes + stay around for some time waiting for the end of their current connections. + +max-spread-checks <delay in milliseconds> + By default, HAProxy tries to spread the start of health checks across the + smallest health check interval of all the servers in a farm. The principle is + to avoid hammering services running on the same server. But when using large + check intervals (10 seconds or more), the last servers in the farm take some + time before starting to be tested, which can be a problem. This parameter is + used to enforce an upper bound on delay between the first and the last check, + even if the servers' check intervals are larger. When servers run with + shorter intervals, their intervals will be respected though. + +maxcompcpuusage <number> + Sets the maximum CPU usage HAProxy can reach before stopping the compression + for new requests or decreasing the compression level of current requests. + It works like 'maxcomprate' but measures CPU usage instead of incoming data + bandwidth. The value is expressed in percent of the CPU used by HAProxy. A + value of 100 disable the limit. The default value is 100. Setting a lower + value will prevent the compression work from slowing the whole process down + and from introducing high latencies. + +maxcomprate <number> + Sets the maximum per-process input compression rate to <number> kilobytes + per second. For each session, if the maximum is reached, the compression + level will be decreased during the session. If the maximum is reached at the + beginning of a session, the session will not compress at all. If the maximum + is not reached, the compression level will be increased up to + tune.comp.maxlevel. A value of zero means there is no limit, this is the + default value. + +maxconn <number> + Sets the maximum per-process number of concurrent connections to <number>. It + is equivalent to the command-line argument "-n". Proxies will stop accepting + connections when this limit is reached. The "ulimit-n" parameter is + automatically adjusted according to this value. See also "ulimit-n". Note: + the "select" poller cannot reliably use more than 1024 file descriptors on + some platforms. If your platform only supports select and reports "select + FAILED" on startup, you need to reduce maxconn until it works (slightly + below 500 in general). If this value is not set, it will automatically be + calculated based on the current file descriptors limit reported by the + "ulimit -n" command, possibly reduced to a lower value if a memory limit + is enforced, based on the buffer size, memory allocated to compression, SSL + cache size, and use or not of SSL and the associated maxsslconn (which can + also be automatic). In any case, the fd-hard-limit applies if set. + + See also: fd-hard-limit, ulimit-n + +maxconnrate <number> + Sets the maximum per-process number of connections per second to <number>. + Proxies will stop accepting connections when this limit is reached. It can be + used to limit the global capacity regardless of each frontend capacity. It is + important to note that this can only be used as a service protection measure, + as there will not necessarily be a fair share between frontends when the + limit is reached, so it's a good idea to also limit each frontend to some + value close to its expected share. Also, lowering tune.maxaccept can improve + fairness. + +maxpipes <number> + Sets the maximum per-process number of pipes to <number>. Currently, pipes + are only used by kernel-based tcp splicing. Since a pipe contains two file + descriptors, the "ulimit-n" value will be increased accordingly. The default + value is maxconn/4, which seems to be more than enough for most heavy usages. + The splice code dynamically allocates and releases pipes, and can fall back + to standard copy, so setting this value too low may only impact performance. + +maxsessrate <number> + Sets the maximum per-process number of sessions per second to <number>. + Proxies will stop accepting connections when this limit is reached. It can be + used to limit the global capacity regardless of each frontend capacity. It is + important to note that this can only be used as a service protection measure, + as there will not necessarily be a fair share between frontends when the + limit is reached, so it's a good idea to also limit each frontend to some + value close to its expected share. Also, lowering tune.maxaccept can improve + fairness. + +maxsslconn <number> + Sets the maximum per-process number of concurrent SSL connections to + <number>. By default there is no SSL-specific limit, which means that the + global maxconn setting will apply to all connections. Setting this limit + avoids having openssl use too much memory and crash when malloc returns NULL + (since it unfortunately does not reliably check for such conditions). Note + that the limit applies both to incoming and outgoing connections, so one + connection which is deciphered then ciphered accounts for 2 SSL connections. + If this value is not set, but a memory limit is enforced, this value will be + automatically computed based on the memory limit, maxconn, the buffer size, + memory allocated to compression, SSL cache size, and use of SSL in either + frontends, backends or both. If neither maxconn nor maxsslconn are specified + when there is a memory limit, HAProxy will automatically adjust these values + so that 100% of the connections can be made over SSL with no risk, and will + consider the sides where it is enabled (frontend, backend, both). + +maxsslrate <number> + Sets the maximum per-process number of SSL sessions per second to <number>. + SSL listeners will stop accepting connections when this limit is reached. It + can be used to limit the global SSL CPU usage regardless of each frontend + capacity. It is important to note that this can only be used as a service + protection measure, as there will not necessarily be a fair share between + frontends when the limit is reached, so it's a good idea to also limit each + frontend to some value close to its expected share. It is also important to + note that the sessions are accounted before they enter the SSL stack and not + after, which also protects the stack against bad handshakes. Also, lowering + tune.maxaccept can improve fairness. + +maxzlibmem <number> + Sets the maximum amount of RAM in megabytes per process usable by the zlib. + When the maximum amount is reached, future sessions will not compress as long + as RAM is unavailable. When sets to 0, there is no limit. + The default value is 0. The value is available in bytes on the UNIX socket + with "show info" on the line "MaxZlibMemUsage", the memory used by zlib is + "ZlibMemUsage" in bytes. + +no-memory-trimming + Disables memory trimming ("malloc_trim") at a few moments where attempts are + made to reclaim lots of memory (on memory shortage or on reload). Trimming + memory forces the system's allocator to scan all unused areas and to release + them. This is generally seen as nice action to leave more available memory to + a new process while the old one is unlikely to make significant use of it. + But some systems dealing with tens to hundreds of thousands of concurrent + connections may experience a lot of memory fragmentation, that may render + this release operation extremely long. During this time, no more traffic + passes through the process, new connections are not accepted anymore, some + health checks may even fail, and the watchdog may even trigger and kill the + unresponsive process, leaving a huge core dump. If this ever happens, then it + is suggested to use this option to disable trimming and stop trying to be + nice with the new process. Note that advanced memory allocators usually do + not suffer from such a problem. + +noepoll + Disables the use of the "epoll" event polling system on Linux. It is + equivalent to the command-line argument "-de". The next polling system + used will generally be "poll". See also "nopoll". + +noevports + Disables the use of the event ports event polling system on SunOS systems + derived from Solaris 10 and later. It is equivalent to the command-line + argument "-dv". The next polling system used will generally be "poll". See + also "nopoll". + +nogetaddrinfo + Disables the use of getaddrinfo(3) for name resolving. It is equivalent to + the command line argument "-dG". Deprecated gethostbyname(3) will be used. + +nokqueue + Disables the use of the "kqueue" event polling system on BSD. It is + equivalent to the command-line argument "-dk". The next polling system + used will generally be "poll". See also "nopoll". + +nopoll + Disables the use of the "poll" event polling system. It is equivalent to the + command-line argument "-dp". The next polling system used will be "select". + It should never be needed to disable "poll" since it's available on all + platforms supported by HAProxy. See also "nokqueue", "noepoll" and + "noevports". + +noreuseport + Disables the use of SO_REUSEPORT - see socket(7). It is equivalent to the + command line argument "-dR". + +nosplice + Disables the use of kernel tcp splicing between sockets on Linux. It is + equivalent to the command line argument "-dS". Data will then be copied + using conventional and more portable recv/send calls. Kernel tcp splicing is + limited to some very recent instances of kernel 2.6. Most versions between + 2.6.25 and 2.6.28 are buggy and will forward corrupted data, so they must not + be used. This option makes it easier to globally disable kernel splicing in + case of doubt. See also "option splice-auto", "option splice-request" and + "option splice-response". + +profiling.memory { on | off } + Enables ('on') or disables ('off') per-function memory profiling. This will + keep usage statistics of malloc/calloc/realloc/free calls anywhere in the + process (including libraries) which will be reported on the CLI using the + "show profiling" command. This is essentially meant to be used when an + abnormal memory usage is observed that cannot be explained by the pools and + other info are required. The performance hit will typically be around 1%, + maybe a bit more on highly threaded machines, so it is normally suitable for + use in production. The same may be achieved at run time on the CLI using the + "set profiling memory" command, please consult the management manual. + +profiling.tasks { auto | on | off } + Enables ('on') or disables ('off') per-task CPU profiling. When set to 'auto' + the profiling automatically turns on a thread when it starts to suffer from + an average latency of 1000 microseconds or higher as reported in the + "avg_loop_us" activity field, and automatically turns off when the latency + returns below 990 microseconds (this value is an average over the last 1024 + loops so it does not vary quickly and tends to significantly smooth short + spikes). It may also spontaneously trigger from time to time on overloaded + systems, containers, or virtual machines, or when the system swaps (which + must absolutely never happen on a load balancer). + + CPU profiling per task can be very convenient to report where the time is + spent and which requests have what effect on which other request. Enabling + it will typically affect the overall's performance by less than 1%, thus it + is recommended to leave it to the default 'auto' value so that it only + operates when a problem is identified. This feature requires a system + supporting the clock_gettime(2) syscall with clock identifiers + CLOCK_MONOTONIC and CLOCK_THREAD_CPUTIME_ID, otherwise the reported time will + be zero. This option may be changed at run time using "set profiling" on the + CLI. + +spread-checks <0..50, in percent> + Sometimes it is desirable to avoid sending agent and health checks to + servers at exact intervals, for instance when many logical servers are + located on the same physical server. With the help of this parameter, it + becomes possible to add some randomness in the check interval between 0 + and +/- 50%. A value between 2 and 5 seems to show good results. The + default value remains at 0. + +ssl-engine <name> [algo <comma-separated list of algorithms>] + Sets the OpenSSL engine to <name>. List of valid values for <name> may be + obtained using the command "openssl engine". This statement may be used + multiple times, it will simply enable multiple crypto engines. Referencing an + unsupported engine will prevent HAProxy from starting. Note that many engines + will lead to lower HTTPS performance than pure software with recent + processors. The optional command "algo" sets the default algorithms an ENGINE + will supply using the OPENSSL function ENGINE_set_default_string(). A value + of "ALL" uses the engine for all cryptographic operations. If no list of + algo is specified then the value of "ALL" is used. A comma-separated list + of different algorithms may be specified, including: RSA, DSA, DH, EC, RAND, + CIPHERS, DIGESTS, PKEY, PKEY_CRYPTO, PKEY_ASN1. This is the same format that + openssl configuration file uses: + https://www.openssl.org/docs/man1.0.2/apps/config.html + +ssl-mode-async + Adds SSL_MODE_ASYNC mode to the SSL context. This enables asynchronous TLS + I/O operations if asynchronous capable SSL engines are used. The current + implementation supports a maximum of 32 engines. The Openssl ASYNC API + doesn't support moving read/write buffers and is not compliant with + HAProxy's buffer management. So the asynchronous mode is disabled on + read/write operations (it is only enabled during initial and renegotiation + handshakes). + +tune.buffers.limit <number> + Sets a hard limit on the number of buffers which may be allocated per process. + The default value is zero which means unlimited. The minimum non-zero value + will always be greater than "tune.buffers.reserve" and should ideally always + be about twice as large. Forcing this value can be particularly useful to + limit the amount of memory a process may take, while retaining a sane + behavior. When this limit is reached, sessions which need a buffer wait for + another one to be released by another session. Since buffers are dynamically + allocated and released, the waiting time is very short and not perceptible + provided that limits remain reasonable. In fact sometimes reducing the limit + may even increase performance by increasing the CPU cache's efficiency. Tests + have shown good results on average HTTP traffic with a limit to 1/10 of the + expected global maxconn setting, which also significantly reduces memory + usage. The memory savings come from the fact that a number of connections + will not allocate 2*tune.bufsize. It is best not to touch this value unless + advised to do so by an HAProxy core developer. + +tune.buffers.reserve <number> + Sets the number of buffers which are pre-allocated and reserved for use only + during memory shortage conditions resulting in failed memory allocations. The + minimum value is 2 and is also the default. There is no reason a user would + want to change this value, it's mostly aimed at HAProxy core developers. + +tune.bufsize <number> + Sets the buffer size to this size (in bytes). Lower values allow more + sessions to coexist in the same amount of RAM, and higher values allow some + applications with very large cookies to work. The default value is 16384 and + can be changed at build time. It is strongly recommended not to change this + from the default value, as very low values will break some services such as + statistics, and values larger than default size will increase memory usage, + possibly causing the system to run out of memory. At least the global maxconn + parameter should be decreased by the same factor as this one is increased. In + addition, use of HTTP/2 mandates that this value must be 16384 or more. If an + HTTP request is larger than (tune.bufsize - tune.maxrewrite), HAProxy will + return HTTP 400 (Bad Request) error. Similarly if an HTTP response is larger + than this size, HAProxy will return HTTP 502 (Bad Gateway). Note that the + value set using this parameter will automatically be rounded up to the next + multiple of 8 on 32-bit machines and 16 on 64-bit machines. + +tune.comp.maxlevel <number> + Sets the maximum compression level. The compression level affects CPU + usage during compression. This value affects CPU usage during compression. + Each session using compression initializes the compression algorithm with + this value. The default value is 1. + +tune.fail-alloc + If compiled with DEBUG_FAIL_ALLOC or started with "-dMfail", gives the + percentage of chances an allocation attempt fails. Must be between 0 (no + failure) and 100 (no success). This is useful to debug and make sure memory + failures are handled gracefully. + +tune.fd.edge-triggered { on | off } [ EXPERIMENTAL ] + Enables ('on') or disables ('off') the edge-triggered polling mode for FDs + that support it. This is currently only support with epoll. It may noticeably + reduce the number of epoll_ctl() calls and slightly improve performance in + certain scenarios. This is still experimental, it may result in frozen + connections if bugs are still present, and is disabled by default. + +tune.h2.header-table-size <number> + Sets the HTTP/2 dynamic header table size. It defaults to 4096 bytes and + cannot be larger than 65536 bytes. A larger value may help certain clients + send more compact requests, depending on their capabilities. This amount of + memory is consumed for each HTTP/2 connection. It is recommended not to + change it. + +tune.h2.initial-window-size <number> + Sets the HTTP/2 initial window size, which is the number of bytes the client + can upload before waiting for an acknowledgment from HAProxy. This setting + only affects payload contents (i.e. the body of POST requests), not headers. + The default value is 65535, which roughly allows up to 5 Mbps of upload + bandwidth per client over a network showing a 100 ms ping time, or 500 Mbps + over a 1-ms local network. It can make sense to increase this value to allow + faster uploads, or to reduce it to increase fairness when dealing with many + clients. It doesn't affect resource usage. + +tune.h2.max-concurrent-streams <number> + Sets the HTTP/2 maximum number of concurrent streams per connection (ie the + number of outstanding requests on a single connection). The default value is + 100. A larger one may slightly improve page load time for complex sites when + visited over high latency networks, but increases the amount of resources a + single client may allocate. A value of zero disables the limit so a single + client may create as many streams as allocatable by HAProxy. It is highly + recommended not to change this value. + +tune.h2.max-frame-size <number> + Sets the HTTP/2 maximum frame size that HAProxy announces it is willing to + receive to its peers. The default value is the largest between 16384 and the + buffer size (tune.bufsize). In any case, HAProxy will not announce support + for frame sizes larger than buffers. The main purpose of this setting is to + allow to limit the maximum frame size setting when using large buffers. Too + large frame sizes might have performance impact or cause some peers to + misbehave. It is highly recommended not to change this value. + +tune.http.cookielen <number> + Sets the maximum length of captured cookies. This is the maximum value that + the "capture cookie xxx len yyy" will be allowed to take, and any upper value + will automatically be truncated to this one. It is important not to set too + high a value because all cookie captures still allocate this size whatever + their configured value (they share a same pool). This value is per request + per response, so the memory allocated is twice this value per connection. + When not specified, the limit is set to 63 characters. It is recommended not + to change this value. + +tune.http.logurilen <number> + Sets the maximum length of request URI in logs. This prevents truncating long + request URIs with valuable query strings in log lines. This is not related + to syslog limits. If you increase this limit, you may also increase the + 'log ... len yyy' parameter. Your syslog daemon may also need specific + configuration directives too. + The default value is 1024. + +tune.http.maxhdr <number> + Sets the maximum number of headers in a request. When a request comes with a + number of headers greater than this value (including the first line), it is + rejected with a "400 Bad Request" status code. Similarly, too large responses + are blocked with "502 Bad Gateway". The default value is 101, which is enough + for all usages, considering that the widely deployed Apache server uses the + same limit. It can be useful to push this limit further to temporarily allow + a buggy application to work by the time it gets fixed. The accepted range is + 1..32767. Keep in mind that each new header consumes 32bits of memory for + each session, so don't push this limit too high. + +tune.idle-pool.shared { on | off } + Enables ('on') or disables ('off') sharing of idle connection pools between + threads for a same server. The default is to share them between threads in + order to minimize the number of persistent connections to a server, and to + optimize the connection reuse rate. But to help with debugging or when + suspecting a bug in HAProxy around connection reuse, it can be convenient to + forcefully disable this idle pool sharing between multiple threads, and force + this option to "off". The default is on. It is strongly recommended against + disabling this option without setting a conservative value on "pool-low-conn" + for all servers relying on connection reuse to achieve a high performance + level, otherwise connections might be closed very often as the thread count + increases. + +tune.idletimer <timeout> + Sets the duration after which HAProxy will consider that an empty buffer is + probably associated with an idle stream. This is used to optimally adjust + some packet sizes while forwarding large and small data alternatively. The + decision to use splice() or to send large buffers in SSL is modulated by this + parameter. The value is in milliseconds between 0 and 65535. A value of zero + means that HAProxy will not try to detect idle streams. The default is 1000, + which seems to correctly detect end user pauses (e.g. read a page before + clicking). There should be no reason for changing this value. Please check + tune.ssl.maxrecord below. + +tune.listener.multi-queue { on | off } + Enables ('on') or disables ('off') the listener's multi-queue accept which + spreads the incoming traffic to all threads a "bind" line is allowed to run + on instead of taking them for itself. This provides a smoother traffic + distribution and scales much better, especially in environments where threads + may be unevenly loaded due to external activity (network interrupts colliding + with one thread for example). This option is enabled by default, but it may + be forcefully disabled for troubleshooting or for situations where it is + estimated that the operating system already provides a good enough + distribution and connections are extremely short-lived. + +tune.lua.forced-yield <number> + This directive forces the Lua engine to execute a yield each <number> of + instructions executed. This permits interrupting a long script and allows the + HAProxy scheduler to process other tasks like accepting connections or + forwarding traffic. The default value is 10000 instructions. If HAProxy often + executes some Lua code but more responsiveness is required, this value can be + lowered. If the Lua code is quite long and its result is absolutely required + to process the data, the <number> can be increased. + +tune.lua.maxmem + Sets the maximum amount of RAM in megabytes per process usable by Lua. By + default it is zero which means unlimited. It is important to set a limit to + ensure that a bug in a script will not result in the system running out of + memory. + +tune.lua.session-timeout <timeout> + This is the execution timeout for the Lua sessions. This is useful for + preventing infinite loops or spending too much time in Lua. This timeout + counts only the pure Lua runtime. If the Lua does a sleep, the sleep is + not taken in account. The default timeout is 4s. + +tune.lua.service-timeout <timeout> + This is the execution timeout for the Lua services. This is useful for + preventing infinite loops or spending too much time in Lua. This timeout + counts only the pure Lua runtime. If the Lua does a sleep, the sleep is + not taken in account. The default timeout is 4s. + +tune.lua.task-timeout <timeout> + Purpose is the same as "tune.lua.session-timeout", but this timeout is + dedicated to the tasks. By default, this timeout isn't set because a task may + remain alive during of the lifetime of HAProxy. For example, a task used to + check servers. + +tune.maxaccept <number> + Sets the maximum number of consecutive connections a process may accept in a + row before switching to other work. In single process mode, higher numbers + used to give better performance at high connection rates, though this is not + the case anymore with the multi-queue. This value applies individually to + each listener, so that the number of processes a listener is bound to is + taken into account. This value defaults to 4 which showed best results. If a + significantly higher value was inherited from an ancient config, it might be + worth removing it as it will both increase performance and lower response + time. In multi-process mode, it is divided by twice the number of processes + the listener is bound to. Setting this value to -1 completely disables the + limitation. It should normally not be needed to tweak this value. + +tune.maxpollevents <number> + Sets the maximum amount of events that can be processed at once in a call to + the polling system. The default value is adapted to the operating system. It + has been noticed that reducing it below 200 tends to slightly decrease + latency at the expense of network bandwidth, and increasing it above 200 + tends to trade latency for slightly increased bandwidth. + +tune.maxrewrite <number> + Sets the reserved buffer space to this size in bytes. The reserved space is + used for header rewriting or appending. The first reads on sockets will never + fill more than bufsize-maxrewrite. Historically it has defaulted to half of + bufsize, though that does not make much sense since there are rarely large + numbers of headers to add. Setting it too high prevents processing of large + requests or responses. Setting it too low prevents addition of new headers + to already large requests or to POST requests. It is generally wise to set it + to about 1024. It is automatically readjusted to half of bufsize if it is + larger than that. This means you don't have to worry about it when changing + bufsize. + +tune.pattern.cache-size <number> + Sets the size of the pattern lookup cache to <number> entries. This is an LRU + cache which reminds previous lookups and their results. It is used by ACLs + and maps on slow pattern lookups, namely the ones using the "sub", "reg", + "dir", "dom", "end", "bin" match methods as well as the case-insensitive + strings. It applies to pattern expressions which means that it will be able + to memorize the result of a lookup among all the patterns specified on a + configuration line (including all those loaded from files). It automatically + invalidates entries which are updated using HTTP actions or on the CLI. The + default cache size is set to 10000 entries, which limits its footprint to + about 5 MB per process/thread on 32-bit systems and 8 MB per process/thread + on 64-bit systems, as caches are thread/process local. There is a very low + risk of collision in this cache, which is in the order of the size of the + cache divided by 2^64. Typically, at 10000 requests per second with the + default cache size of 10000 entries, there's 1% chance that a brute force + attack could cause a single collision after 60 years, or 0.1% after 6 years. + This is considered much lower than the risk of a memory corruption caused by + aging components. If this is not acceptable, the cache can be disabled by + setting this parameter to 0. + +tune.peers.max-updates-at-once <number> + Sets the maximum number of stick-table updates that haproxy will try to + process at once when sending messages. Retrieving the data for these updates + requires some locking operations which can be CPU intensive on highly + threaded machines if unbound, and may also increase the traffic latency + during the initial batched transfer between an older and a newer process. + Conversely low values may also incur higher CPU overhead, and take longer + to complete. The default value is 200 and it is suggested not to change it. + +tune.pipesize <number> + Sets the kernel pipe buffer size to this size (in bytes). By default, pipes + are the default size for the system. But sometimes when using TCP splicing, + it can improve performance to increase pipe sizes, especially if it is + suspected that pipes are not filled and that many calls to splice() are + performed. This has an impact on the kernel's memory footprint, so this must + not be changed if impacts are not understood. + +tune.pool-high-fd-ratio <number> + This setting sets the max number of file descriptors (in percentage) used by + HAProxy globally against the maximum number of file descriptors HAProxy can + use before we start killing idle connections when we can't reuse a connection + and we have to create a new one. The default is 25 (one quarter of the file + descriptor will mean that roughly half of the maximum front connections can + keep an idle connection behind, anything beyond this probably doesn't make + much sense in the general case when targeting connection reuse). + +tune.pool-low-fd-ratio <number> + This setting sets the max number of file descriptors (in percentage) used by + HAProxy globally against the maximum number of file descriptors HAProxy can + use before we stop putting connection into the idle pool for reuse. The + default is 20. + +tune.quic.frontend.conn-tx-buffers.limit <number> + Warning: QUIC support in HAProxy is currently experimental. Configuration may + change without deprecation in the future. + + This settings defines the maximum number of buffers allocated for a QUIC + connection on data emission. By default, it is set to 30. QUIC buffers are + drained on ACK reception. This setting has a direct impact on the throughput + and memory consumption and can be adjusted according to an estimated round + time-trip. Each buffer is tune.bufsize. + +tune.quic.frontend.max-idle-timeout <timeout> + Warning: QUIC support in HAProxy is currently experimental. Configuration may + change without deprecation in the future. + + Sets the QUIC max_idle_timeout transport parameters in milliseconds for + frontends which determines the period of time after which a connection silently + closes if it has remained inactive during an effective period of time deduced + from the two max_idle_timeout values announced by the two endpoints: + - the minimum of the two values if both are not null, + - the maximum if only one of them is not null, + - if both values are null, this feature is disabled. + + The default value is 30000. + +tune.quic.frontend.max-streams-bidi <number> + Warning: QUIC support in HAProxy is currently experimental. Configuration may + change without deprecation in the future. + + Sets the QUIC initial_max_streams_bidi transport parameter for frontends. + This is the initial maximum number of bidirectional streams the remote peer + will be authorized to open. This determines the number of concurrent client + requests. + + The default value is 100. + +tune.quic.retry-threshold <number> + Warning: QUIC support in HAProxy is currently experimental. Configuration may + change without deprecation in the future. + + Dynamically enables the Retry feature for all the configured QUIC listeners + as soon as this number of half open connections is reached. A half open + connection is a connection whose handshake has not already successfully + completed or failed. To be functional this setting needs a cluster secret to + be set, if not it will be silently ignored (see "cluster-secret" setting). + This setting will be also silently ignored if the use of QUIC Retry was + forced (see "quic-force-retry"). + + The default value is 100. + + See https://www.rfc-editor.org/rfc/rfc9000.html#section-8.1.2 for more + information about QUIC retry. + +tune.rcvbuf.client <number> +tune.rcvbuf.server <number> + Forces the kernel socket receive buffer size on the client or the server side + to the specified value in bytes. This value applies to all TCP/HTTP frontends + and backends. It should normally never be set, and the default size (0) lets + the kernel auto-tune this value depending on the amount of available memory. + However it can sometimes help to set it to very low values (e.g. 4096) in + order to save kernel memory by preventing it from buffering too large amounts + of received data. Lower values will significantly increase CPU usage though. + +tune.recv_enough <number> + HAProxy uses some hints to detect that a short read indicates the end of the + socket buffers. One of them is that a read returns more than <recv_enough> + bytes, which defaults to 10136 (7 segments of 1448 each). This default value + may be changed by this setting to better deal with workloads involving lots + of short messages such as telnet or SSH sessions. + +tune.runqueue-depth <number> + Sets the maximum amount of task that can be processed at once when running + tasks. The default value depends on the number of threads but sits between 35 + and 280, which tend to show the highest request rates and lowest latencies. + Increasing it may incur latency when dealing with I/Os, making it too small + can incur extra overhead. Higher thread counts benefit from lower values. + When experimenting with much larger values, it may be useful to also enable + tune.sched.low-latency and possibly tune.fd.edge-triggered to limit the + maximum latency to the lowest possible. + +tune.sched.low-latency { on | off } + Enables ('on') or disables ('off') the low-latency task scheduler. By default + HAProxy processes tasks from several classes one class at a time as this is + the most efficient. But when running with large values of tune.runqueue-depth + this can have a measurable effect on request or connection latency. When this + low-latency setting is enabled, tasks of lower priority classes will always + be executed before other ones if they exist. This will permit to lower the + maximum latency experienced by new requests or connections in the middle of + massive traffic, at the expense of a higher impact on this large traffic. + For regular usage it is better to leave this off. The default value is off. + +tune.sndbuf.client <number> +tune.sndbuf.server <number> + Forces the kernel socket send buffer size on the client or the server side to + the specified value in bytes. This value applies to all TCP/HTTP frontends + and backends. It should normally never be set, and the default size (0) lets + the kernel auto-tune this value depending on the amount of available memory. + However it can sometimes help to set it to very low values (e.g. 4096) in + order to save kernel memory by preventing it from buffering too large amounts + of received data. Lower values will significantly increase CPU usage though. + Another use case is to prevent write timeouts with extremely slow clients due + to the kernel waiting for a large part of the buffer to be read before + notifying HAProxy again. + +tune.ssl.cachesize <number> + Sets the size of the global SSL session cache, in a number of blocks. A block + is large enough to contain an encoded session without peer certificate. An + encoded session with peer certificate is stored in multiple blocks depending + on the size of the peer certificate. A block uses approximately 200 bytes of + memory (based on `sizeof(struct sh_ssl_sess_hdr) + SHSESS_BLOCK_MIN_SIZE` + calculation used for `shctx_init` function). The default value may be forced + at build time, otherwise defaults to 20000. When the cache is full, the most + idle entries are purged and reassigned. Higher values reduce the occurrence + of such a purge, hence the number of CPU-intensive SSL handshakes by ensuring + that all users keep their session as long as possible. All entries are + pre-allocated upon startup. Setting this value to 0 disables the SSL session + cache. + +tune.ssl.capture-buffer-size <number> +tune.ssl.capture-cipherlist-size <number> (deprecated) + Sets the maximum size of the buffer used for capturing client hello cipher + list, extensions list, elliptic curves list and elliptic curve point + formats. If the value is 0 (default value) the capture is disabled, + otherwise a buffer is allocated for each SSL/TLS connection. + +tune.ssl.default-dh-param <number> + Sets the maximum size of the Diffie-Hellman parameters used for generating + the ephemeral/temporary Diffie-Hellman key in case of DHE key exchange. The + final size will try to match the size of the server's RSA (or DSA) key (e.g, + a 2048 bits temporary DH key for a 2048 bits RSA key), but will not exceed + this maximum value. Only 1024 or higher values are allowed. Higher values + will increase the CPU load, and values greater than 1024 bits are not + supported by Java 7 and earlier clients. This value is not used if static + Diffie-Hellman parameters are supplied either directly in the certificate + file or by using the ssl-dh-param-file parameter. + If there is neither a default-dh-param nor a ssl-dh-param-file defined, and + if the server's PEM file of a given frontend does not specify its own DH + parameters, then DHE ciphers will be unavailable for this frontend. + +tune.ssl.force-private-cache + This option disables SSL session cache sharing between all processes. It + should normally not be used since it will force many renegotiations due to + clients hitting a random process. But it may be required on some operating + systems where none of the SSL cache synchronization method may be used. In + this case, adding a first layer of hash-based load balancing before the SSL + layer might limit the impact of the lack of session sharing. + +tune.ssl.hard-maxrecord <number> + Sets the maximum amount of bytes passed to SSL_write() at any time. Default + value 0 means there is no limit. In contrast to tune.ssl.maxrecord this + settings will not be adjusted dynamically. Smaller records may decrease + throughput, but may be required when dealing with low-footprint clients. + +tune.ssl.keylog { on | off } + This option activates the logging of the TLS keys. It should be used with + care as it will consume more memory per SSL session and could decrease + performances. This is disabled by default. + + These sample fetches should be used to generate the SSLKEYLOGFILE that is + required to decipher traffic with wireshark. + + https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/Key_Log_Format + + The SSLKEYLOG is a series of lines which are formatted this way: + + <Label> <space> <ClientRandom> <space> <Secret> + + The ClientRandom is provided by the %[ssl_fc_client_random,hex] sample + fetch, the secret and the Label could be find in the array below. You need + to generate a SSLKEYLOGFILE with all the labels in this array. + + The following sample fetches are hexadecimal strings and does not need to be + converted. + + SSLKEYLOGFILE Label | Sample fetches for the Secrets + --------------------------------|----------------------------------------- + CLIENT_EARLY_TRAFFIC_SECRET | %[ssl_fc_client_early_traffic_secret] + CLIENT_HANDSHAKE_TRAFFIC_SECRET | %[ssl_fc_client_handshake_traffic_secret] + SERVER_HANDSHAKE_TRAFFIC_SECRET | %[ssl_fc_server_handshake_traffic_secret] + CLIENT_TRAFFIC_SECRET_0 | %[ssl_fc_client_traffic_secret_0] + SERVER_TRAFFIC_SECRET_0 | %[ssl_fc_server_traffic_secret_0] + EXPORTER_SECRET | %[ssl_fc_exporter_secret] + EARLY_EXPORTER_SECRET | %[ssl_fc_early_exporter_secret] + + This is only available with OpenSSL 1.1.1, and useful with TLS1.3 session. + + If you want to generate the content of a SSLKEYLOGFILE with TLS < 1.3, you + only need this line: + + "CLIENT_RANDOM %[ssl_fc_client_random,hex] %[ssl_fc_session_key,hex]" + +tune.ssl.lifetime <timeout> + Sets how long a cached SSL session may remain valid. This time is expressed + in seconds and defaults to 300 (5 min). It is important to understand that it + does not guarantee that sessions will last that long, because if the cache is + full, the longest idle sessions will be purged despite their configured + lifetime. The real usefulness of this setting is to prevent sessions from + being used for too long. + +tune.ssl.maxrecord <number> + Sets the maximum amount of bytes passed to SSL_write() at the beginning of + the data transfer. Default value 0 means there is no limit. Over SSL/TLS, + the client can decipher the data only once it has received a full record. + With large records, it means that clients might have to download up to 16kB + of data before starting to process them. Limiting the value can improve page + load times on browsers located over high latency or low bandwidth networks. + It is suggested to find optimal values which fit into 1 or 2 TCP segments + (generally 1448 bytes over Ethernet with TCP timestamps enabled, or 1460 when + timestamps are disabled), keeping in mind that SSL/TLS add some overhead. + Typical values of 1419 and 2859 gave good results during tests. Use + "strace -e trace=write" to find the best value. HAProxy will automatically + switch to this setting after an idle stream has been detected (see + tune.idletimer above). See also tune.ssl.hard-maxrecord. + +tune.ssl.ssl-ctx-cache-size <number> + Sets the size of the cache used to store generated certificates to <number> + entries. This is a LRU cache. Because generating a SSL certificate + dynamically is expensive, they are cached. The default cache size is set to + 1000 entries. + +tune.vars.global-max-size <size> +tune.vars.proc-max-size <size> +tune.vars.reqres-max-size <size> +tune.vars.sess-max-size <size> +tune.vars.txn-max-size <size> + These five tunes help to manage the maximum amount of memory used by the + variables system. "global" limits the overall amount of memory available for + all scopes. "proc" limits the memory for the process scope, "sess" limits the + memory for the session scope, "txn" for the transaction scope, and "reqres" + limits the memory for each request or response processing. + Memory accounting is hierarchical, meaning more coarse grained limits include + the finer grained ones: "proc" includes "sess", "sess" includes "txn", and + "txn" includes "reqres". + + For example, when "tune.vars.sess-max-size" is limited to 100, + "tune.vars.txn-max-size" and "tune.vars.reqres-max-size" cannot exceed + 100 either. If we create a variable "txn.var" that contains 100 bytes, + all available space is consumed. + Notice that exceeding the limits at runtime will not result in an error + message, but values might be cut off or corrupted. So make sure to accurately + plan for the amount of space needed to store all your variables. + +tune.zlib.memlevel <number> + Sets the memLevel parameter in zlib initialization for each session. It + defines how much memory should be allocated for the internal compression + state. A value of 1 uses minimum memory but is slow and reduces compression + ratio, a value of 9 uses maximum memory for optimal speed. Can be a value + between 1 and 9. The default value is 8. + +tune.zlib.windowsize <number> + Sets the window size (the size of the history buffer) as a parameter of the + zlib initialization for each session. Larger values of this parameter result + in better compression at the expense of memory usage. Can be a value between + 8 and 15. The default value is 15. + +3.3. Debugging +-------------- + +quiet + Do not display any message during startup. It is equivalent to the command- + line argument "-q". + +zero-warning + When this option is set, HAProxy will refuse to start if any warning was + emitted while processing the configuration. It is highly recommended to set + this option on configurations that are not changed often, as it helps detect + subtle mistakes and keep the configuration clean and forward-compatible. Note + that "haproxy -c" will also report errors in such a case. This option is + equivalent to command line argument "-dW". + + +3.4. Userlists +-------------- +It is possible to control access to frontend/backend/listen sections or to +http stats by allowing only authenticated and authorized users. To do this, +it is required to create at least one userlist and to define users. + +userlist <listname> + Creates new userlist with name <listname>. Many independent userlists can be + used to store authentication & authorization data for independent customers. + +group <groupname> [users <user>,<user>,(...)] + Adds group <groupname> to the current userlist. It is also possible to + attach users to this group by using a comma separated list of names + proceeded by "users" keyword. + +user <username> [password|insecure-password <password>] + [groups <group>,<group>,(...)] + Adds user <username> to the current userlist. Both secure (encrypted) and + insecure (unencrypted) passwords can be used. Encrypted passwords are + evaluated using the crypt(3) function, so depending on the system's + capabilities, different algorithms are supported. For example, modern Glibc + based Linux systems support MD5, SHA-256, SHA-512, and, of course, the + classic DES-based method of encrypting passwords. + + Attention: Be aware that using encrypted passwords might cause significantly + increased CPU usage, depending on the number of requests, and the algorithm + used. For any of the hashed variants, the password for each request must + be processed through the chosen algorithm, before it can be compared to the + value specified in the config file. Most current algorithms are deliberately + designed to be expensive to compute to achieve resistance against brute + force attacks. They do not simply salt/hash the clear text password once, + but thousands of times. This can quickly become a major factor in HAProxy's + overall CPU consumption! + + Example: + userlist L1 + group G1 users tiger,scott + group G2 users xdb,scott + + user tiger password $6$k6y3o.eP$JlKBx9za9667qe4(...)xHSwRv6J.C0/D7cV91 + user scott insecure-password elgato + user xdb insecure-password hello + + userlist L2 + group G1 + group G2 + + user tiger password $6$k6y3o.eP$JlKBx(...)xHSwRv6J.C0/D7cV91 groups G1 + user scott insecure-password elgato groups G1,G2 + user xdb insecure-password hello groups G2 + + Please note that both lists are functionally identical. + + +3.5. Peers +---------- +It is possible to propagate entries of any data-types in stick-tables between +several HAProxy instances over TCP connections in a multi-master fashion. Each +instance pushes its local updates and insertions to remote peers. The pushed +values overwrite remote ones without aggregation. As an exception, the data +type "conn_cur" is never learned from peers, as it is supposed to reflect local +values. Earlier versions used to synchronize it and to cause negative values in +active-active setups, and always-growing values upon reloads or active-passive +switches because the local value would reflect more connections than locally +present. This information, however, is pushed so that monitoring systems can +watch it. + +Interrupted exchanges are automatically detected and recovered from the last +known point. In addition, during a soft restart, the old process connects to +the new one using such a TCP connection to push all its entries before the new +process tries to connect to other peers. That ensures very fast replication +during a reload, it typically takes a fraction of a second even for large +tables. + +Note that Server IDs are used to identify servers remotely, so it is important +that configurations look similar or at least that the same IDs are forced on +each server on all participants. + +peers <peersect> + Creates a new peer list with name <peersect>. It is an independent section, + which is referenced by one or more stick-tables. + +bind [<address>]:<port_range> [, ...] [param*] + Defines the binding parameters of the local peer of this "peers" section. + Such lines are not supported with "peer" line in the same "peers" section. + +disabled + Disables a peers section. It disables both listening and any synchronization + related to this section. This is provided to disable synchronization of stick + tables without having to comment out all "peers" references. + +default-bind [param*] + Defines the binding parameters for the local peer, excepted its address. + +default-server [param*] + Change default options for a server in a "peers" section. + + Arguments: + <param*> is a list of parameters for this server. The "default-server" + keyword accepts an important number of options and has a complete + section dedicated to it. In a peers section, the transport + parameters of a "default-server" line are supported. Please refer + to section 5 for more details, and the "server" keyword below in + this section for some of the restrictions. + + See also: "server" and section 5 about server options + +enabled + This re-enables a peers section which was previously disabled via the + "disabled" keyword. + +log <address> [len <length>] [format <format>] [sample <ranges>:<sample_size>] + <facility> [<level> [<minlevel>]] + "peers" sections support the same "log" keyword as for the proxies to + log information about the "peers" listener. See "log" option for proxies for + more details. + +peer <peername> <ip>:<port> [param*] + Defines a peer inside a peers section. + If <peername> is set to the local peer name (by default hostname, or forced + using "-L" command line option or "localpeer" global configuration setting), + HAProxy will listen for incoming remote peer connection on <ip>:<port>. + Otherwise, <ip>:<port> defines where to connect to in order to join the + remote peer, and <peername> is used at the protocol level to identify and + validate the remote peer on the server side. + + During a soft restart, local peer <ip>:<port> is used by the old instance to + connect the new one and initiate a complete replication (teaching process). + + It is strongly recommended to have the exact same peers declaration on all + peers and to only rely on the "-L" command line argument or the "localpeer" + global configuration setting to change the local peer name. This makes it + easier to maintain coherent configuration files across all peers. + + You may want to reference some environment variables in the address + parameter, see section 2.3 about environment variables. + + Note: "peer" keyword may transparently be replaced by "server" keyword (see + "server" keyword explanation below). + +server <peername> [<ip>:<port>] [param*] + As previously mentioned, "peer" keyword may be replaced by "server" keyword + with a support for all "server" parameters found in 5.2 paragraph that are + related to transport settings. If the underlying peer is local, <ip>:<port> + parameters must not be present; these parameters must be provided on a "bind" + line (see "bind" keyword of this "peers" section). + + A number of "server" parameters are irrelevant for "peers" sections. Peers by + nature do not support dynamic host name resolution nor health checks, hence + parameters like "init_addr", "resolvers", "check", "agent-check", or "track" + are not supported. Similarly, there is no load balancing nor stickiness, thus + parameters such as "weight" or "cookie" have no effect. + + Example: + # The old way. + peers mypeers + peer haproxy1 192.168.0.1:1024 + peer haproxy2 192.168.0.2:1024 + peer haproxy3 10.2.0.1:1024 + + backend mybackend + mode tcp + balance roundrobin + stick-table type ip size 20k peers mypeers + stick on src + + server srv1 192.168.0.30:80 + server srv2 192.168.0.31:80 + + Example: + peers mypeers + bind 192.168.0.1:1024 ssl crt mycerts/pem + default-server ssl verify none + server haproxy1 #local peer + server haproxy2 192.168.0.2:1024 + server haproxy3 10.2.0.1:1024 + + +table <tablename> type {ip | integer | string [len <length>] | binary [len <length>]} + size <size> [expire <expire>] [nopurge] [store <data_type>]* + + Configure a stickiness table for the current section. This line is parsed + exactly the same way as the "stick-table" keyword in others section, except + for the "peers" argument which is not required here and with an additional + mandatory first parameter to designate the stick-table. Contrary to others + sections, there may be several "table" lines in "peers" sections (see also + "stick-table" keyword). + + Also be aware of the fact that "peers" sections have their own stick-table + namespaces to avoid collisions between stick-table names identical in + different "peers" section. This is internally handled prepending the "peers" + sections names to the name of the stick-tables followed by a '/' character. + If somewhere else in the configuration file you have to refer to such + stick-tables declared in "peers" sections you must use the prefixed version + of the stick-table name as follows: + + peers mypeers + peer A ... + peer B ... + table t1 ... + + frontend fe1 + tcp-request content track-sc0 src table mypeers/t1 + + This is also this prefixed version of the stick-table names which must be + used to refer to stick-tables through the CLI. + + About "peers" protocol, as only "peers" belonging to the same section may + communicate with each others, there is no need to do such a distinction. + Several "peers" sections may declare stick-tables with the same name. + This is shorter version of the stick-table name which is sent over the network. + There is only a '/' character as prefix to avoid stick-table name collisions between + stick-tables declared as backends and stick-table declared in "peers" sections + as follows in this weird but supported configuration: + + peers mypeers + peer A ... + peer B ... + table t1 type string size 10m store gpc0 + + backend t1 + stick-table type string size 10m store gpc0 peers mypeers + + Here "t1" table declared in "mypeers" section has "mypeers/t1" as global name. + "t1" table declared as a backend as "t1" as global name. But at peer protocol + level the former table is named "/t1", the latter is again named "t1". + +3.6. Mailers +------------ +It is possible to send email alerts when the state of servers changes. +If configured email alerts are sent to each mailer that is configured +in a mailers section. Email is sent to mailers using SMTP. + +mailers <mailersect> + Creates a new mailer list with the name <mailersect>. It is an + independent section which is referenced by one or more proxies. + +mailer <mailername> <ip>:<port> + Defines a mailer inside a mailers section. + + Example: + mailers mymailers + mailer smtp1 192.168.0.1:587 + mailer smtp2 192.168.0.2:587 + + backend mybackend + mode tcp + balance roundrobin + + email-alert mailers mymailers + email-alert from test1@horms.org + email-alert to test2@horms.org + + server srv1 192.168.0.30:80 + server srv2 192.168.0.31:80 + +timeout mail <time> + Defines the time available for a mail/connection to be made and send to + the mail-server. If not defined the default value is 10 seconds. To allow + for at least two SYN-ACK packets to be send during initial TCP handshake it + is advised to keep this value above 4 seconds. + + Example: + mailers mymailers + timeout mail 20s + mailer smtp1 192.168.0.1:587 + +3.7. Programs +------------- +In master-worker mode, it is possible to launch external binaries with the +master, these processes are called programs. These programs are launched and +managed the same way as the workers. + +During a reload of HAProxy, those processes are dealing with the same +sequence as a worker: + + - the master is re-executed + - the master sends a SIGUSR1 signal to the program + - if "option start-on-reload" is not disabled, the master launches a new + instance of the program + +During a stop, or restart, a SIGTERM is sent to the programs. + +program <name> + This is a new program section, this section will create an instance <name> + which is visible in "show proc" on the master CLI. (See "9.4. Master CLI" in + the management guide). + +command <command> [arguments*] + Define the command to start with optional arguments. The command is looked + up in the current PATH if it does not include an absolute path. This is a + mandatory option of the program section. Arguments containing spaces must + be enclosed in quotes or double quotes or be prefixed by a backslash. + +user <user name> + Changes the executed command user ID to the <user name> from /etc/passwd. + See also "group". + +group <group name> + Changes the executed command group ID to the <group name> from /etc/group. + See also "user". + +option start-on-reload +no option start-on-reload + Start (or not) a new instance of the program upon a reload of the master. + The default is to start a new instance. This option may only be used in a + program section. + + +3.8. HTTP-errors +---------------- + +It is possible to globally declare several groups of HTTP errors, to be +imported afterwards in any proxy section. Same group may be referenced at +several places and can be fully or partially imported. + +http-errors <name> + Create a new http-errors group with the name <name>. It is an independent + section that may be referenced by one or more proxies using its name. + +errorfile <code> <file> + Associate a file contents to an HTTP error code + + Arguments : + <code> is the HTTP status code. Currently, HAProxy is capable of + generating codes 200, 400, 401, 403, 404, 405, 407, 408, 410, + 425, 429, 500, 501, 502, 503, and 504. + + <file> designates a file containing the full HTTP response. It is + recommended to follow the common practice of appending ".http" to + the filename so that people do not confuse the response with HTML + error pages, and to use absolute paths, since files are read + before any chroot is performed. + + Please referrers to "errorfile" keyword in section 4 for details. + + Example: + http-errors website-1 + errorfile 400 /etc/haproxy/errorfiles/site1/400.http + errorfile 404 /etc/haproxy/errorfiles/site1/404.http + errorfile 408 /dev/null # work around Chrome pre-connect bug + + http-errors website-2 + errorfile 400 /etc/haproxy/errorfiles/site2/400.http + errorfile 404 /etc/haproxy/errorfiles/site2/404.http + errorfile 408 /dev/null # work around Chrome pre-connect bug + +3.9. Rings +---------- + +It is possible to globally declare ring-buffers, to be used as target for log +servers or traces. + +ring <ringname> + Creates a new ring-buffer with name <ringname>. + +backing-file <path> + This replaces the regular memory allocation by a RAM-mapped file to store the + ring. This can be useful for collecting traces or logs for post-mortem + analysis, without having to attach a slow client to the CLI. Newer contents + will automatically replace older ones so that the latest contents are always + available. The contents written to the ring will be visible in that file once + the process stops (most often they will even be seen very soon after but + there is no such guarantee since writes are not synchronous). + + When this option is used, the total storage area is reduced by the size of + the "struct ring" that starts at the beginning of the area, and that is + required to recover the area's contents. The file will be created with the + starting user's ownership, with mode 0600 and will be of the size configured + by the "size" directive. When the directive is parsed (thus even during + config checks), any existing non-empty file will first be renamed with the + extra suffix ".bak", and any previously existing file with suffix ".bak" will + be removed. This ensures that instant reload or restart of the process will + not wipe precious debugging information, and will leave time for an admin to + spot this new ".bak" file and to archive it if needed. As such, after a crash + the file designated by <path> will contain the freshest information, and if + the service is restarted, the "<path>.bak" file will have it instead. This + means that the total storage capacity required will be double of the ring + size. Failures to rotate the file are silently ignored, so placing the file + into a directory without write permissions will be sufficient to avoid the + backup file if not desired. + + WARNING: there are stability and security implications in using this feature. + First, backing the ring to a slow device (e.g. physical hard drive) may cause + perceptible slowdowns during accesses, and possibly even panics if too many + threads compete for accesses. Second, an external process modifying the area + could cause the haproxy process to crash or to overwrite some of its own + memory with traces. Third, if the file system fills up before the ring, + writes to the ring may cause the process to crash. + + The information present in this ring are structured and are NOT directly + readable using a text editor (even though most of it looks barely readable). + The output of this file is only intended for developers. + +description <text> + The description is an optional description string of the ring. It will + appear on CLI. By default, <name> is reused to fill this field. + +format <format> + Format used to store events into the ring buffer. + + Arguments: + <format> is the log format used when generating syslog messages. It may be + one of the following : + + iso A message containing only the ISO date, followed by the text. + The PID, process name and system name are omitted. This is + designed to be used with a local log server. + + local Analog to rfc3164 syslog message format except that hostname + field is stripped. This is the default. + Note: option "log-send-hostname" switches the default to + rfc3164. + + raw A message containing only the text. The level, PID, date, time, + process name and system name are omitted. This is designed to be + used in containers or during development, where the severity + only depends on the file descriptor used (stdout/stderr). This + is the default. + + rfc3164 The RFC3164 syslog message format. + (https://tools.ietf.org/html/rfc3164) + + rfc5424 The RFC5424 syslog message format. + (https://tools.ietf.org/html/rfc5424) + + short A message containing only a level between angle brackets such as + '<3>', followed by the text. The PID, date, time, process name + and system name are omitted. This is designed to be used with a + local log server. This format is compatible with what the systemd + logger consumes. + + priority A message containing only a level plus syslog facility between angle + brackets such as '<63>', followed by the text. The PID, date, time, + process name and system name are omitted. This is designed to be used + with a local log server. + + timed A message containing only a level between angle brackets such as + '<3>', followed by ISO date and by the text. The PID, process + name and system name are omitted. This is designed to be + used with a local log server. + +maxlen <length> + The maximum length of an event message stored into the ring, + including formatted header. If an event message is longer than + <length>, it will be truncated to this length. + +server <name> <address> [param*] + Used to configure a syslog tcp server to forward messages from ring buffer. + This supports for all "server" parameters found in 5.2 paragraph. Some of + these parameters are irrelevant for "ring" sections. Important point: there + is little reason to add more than one server to a ring, because all servers + will receive the exact same copy of the ring contents, and as such the ring + will progress at the speed of the slowest server. If one server does not + respond, it will prevent old messages from being purged and may block new + messages from being inserted into the ring. The proper way to send messages + to multiple servers is to use one distinct ring per log server, not to + attach multiple servers to the same ring. Note that specific server directive + "log-proto" is used to set the protocol used to send messages. + +size <size> + This is the optional size in bytes for the ring-buffer. Default value is + set to BUFSIZE. + +timeout connect <timeout> + Set the maximum time to wait for a connection attempt to a server to succeed. + + Arguments : + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + +timeout server <timeout> + Set the maximum time for pending data staying into output buffer. + + Arguments : + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + Example: + global + log ring@myring local7 + + ring myring + description "My local buffer" + format rfc3164 + maxlen 1200 + size 32764 + timeout connect 5s + timeout server 10s + server mysyslogsrv 127.0.0.1:6514 log-proto octet-count + +3.10. Log forwarding +------------------- + +It is possible to declare one or multiple log forwarding section, +HAProxy will forward all received log messages to a log servers list. + +log-forward <name> + Creates a new log forwarder proxy identified as <name>. + +backlog <conns> + Give hints to the system about the approximate listen backlog desired size + on connections accept. + +bind <addr> [param*] + Used to configure a stream log listener to receive messages to forward. + This supports the "bind" parameters found in 5.1 paragraph including + those about ssl but some statements such as "alpn" may be irrelevant for + syslog protocol over TCP. + Those listeners support both "Octet Counting" and "Non-Transparent-Framing" + modes as defined in rfc-6587. + +dgram-bind <addr> [param*] + Used to configure a datagram log listener to receive messages to forward. + Addresses must be in IPv4 or IPv6 form,followed by a port. This supports + for some of the "bind" parameters found in 5.1 paragraph among which + "interface", "namespace" or "transparent", the other ones being + silently ignored as irrelevant for UDP/syslog case. + +log global +log <address> [len <length>] [format <format>] [sample <ranges>:<sample_size>] + <facility> [<level> [<minlevel>]] + Used to configure target log servers. See more details on proxies + documentation. + If no format specified, HAProxy tries to keep the incoming log format. + Configured facility is ignored, except if incoming message does not + present a facility but one is mandatory on the outgoing format. + If there is no timestamp available in the input format, but the field + exists in output format, HAProxy will use the local date. + + Example: + global + log stderr format iso local7 + + ring myring + description "My local buffer" + format rfc5424 + maxlen 1200 + size 32764 + timeout connect 5s + timeout server 10s + # syslog tcp server + server mysyslogsrv 127.0.0.1:514 log-proto octet-count + + log-forward sylog-loadb + dgram-bind 127.0.0.1:1514 + bind 127.0.0.1:1514 + # all messages on stderr + log global + # all messages on local tcp syslog server + log ring@myring local0 + # load balance messages on 4 udp syslog servers + log 127.0.0.1:10001 sample 1:4 local0 + log 127.0.0.1:10002 sample 2:4 local0 + log 127.0.0.1:10003 sample 3:4 local0 + log 127.0.0.1:10004 sample 4:4 local0 + +maxconn <conns> + Fix the maximum number of concurrent connections on a log forwarder. + 10 is the default. + +timeout client <timeout> + Set the maximum inactivity time on the client side. + +4. Proxies +---------- + +Proxy configuration can be located in a set of sections : + - defaults [<name>] [ from <defaults_name> ] + - frontend <name> [ from <defaults_name> ] + - backend <name> [ from <defaults_name> ] + - listen <name> [ from <defaults_name> ] + +A "frontend" section describes a set of listening sockets accepting client +connections. + +A "backend" section describes a set of servers to which the proxy will connect +to forward incoming connections. + +A "listen" section defines a complete proxy with its frontend and backend +parts combined in one section. It is generally useful for TCP-only traffic. + +A "defaults" section resets all settings to the documented ones and presets new +ones for use by subsequent sections. All of "frontend", "backend" and "listen" +sections always take their initial settings from a defaults section, by default +the latest one that appears before the newly created section. It is possible to +explicitly designate a specific "defaults" section to load the initial settings +from by indicating its name on the section line after the optional keyword +"from". While "defaults" section do not impose a name, this use is encouraged +for better readability. It is also the only way to designate a specific section +to use instead of the default previous one. Since "defaults" section names are +optional, by default a very permissive check is applied on their name and these +are even permitted to overlap. However if a "defaults" section is referenced by +any other section, its name must comply with the syntax imposed on all proxy +names, and this name must be unique among the defaults sections. Please note +that regardless of what is currently permitted, it is recommended to avoid +duplicate section names in general and to respect the same syntax as for proxy +names. This rule might be enforced in a future version. In addition, a warning +is emitted if a defaults section is explicitly used by a proxy while it is also +implicitly used by another one because it is the last one defined. It is highly +encouraged to not mix both usages by always using explicit references or by +adding a last common defaults section reserved for all implicit uses. + +Note that it is even possible for a defaults section to take its initial +settings from another one, and as such, inherit settings across multiple levels +of defaults sections. This can be convenient to establish certain configuration +profiles to carry groups of default settings (e.g. TCP vs HTTP or short vs long +timeouts) but can quickly become confusing to follow. + +All proxy names must be formed from upper and lower case letters, digits, +'-' (dash), '_' (underscore) , '.' (dot) and ':' (colon). ACL names are +case-sensitive, which means that "www" and "WWW" are two different proxies. + +Historically, all proxy names could overlap, it just caused troubles in the +logs. Since the introduction of content switching, it is mandatory that two +proxies with overlapping capabilities (frontend/backend) have different names. +However, it is still permitted that a frontend and a backend share the same +name, as this configuration seems to be commonly encountered. + +Right now, two major proxy modes are supported : "tcp", also known as layer 4, +and "http", also known as layer 7. In layer 4 mode, HAProxy simply forwards +bidirectional traffic between two sides. In layer 7 mode, HAProxy analyzes the +protocol, and can interact with it by allowing, blocking, switching, adding, +modifying, or removing arbitrary contents in requests or responses, based on +arbitrary criteria. + +In HTTP mode, the processing applied to requests and responses flowing over +a connection depends in the combination of the frontend's HTTP options and +the backend's. HAProxy supports 3 connection modes : + + - KAL : keep alive ("option http-keep-alive") which is the default mode : all + requests and responses are processed, and connections remain open but idle + between responses and new requests. + + - SCL: server close ("option http-server-close") : the server-facing + connection is closed after the end of the response is received, but the + client-facing connection remains open. + + - CLO: close ("option httpclose"): the connection is closed after the end of + the response and "Connection: close" appended in both directions. + +The effective mode that will be applied to a connection passing through a +frontend and a backend can be determined by both proxy modes according to the +following matrix, but in short, the modes are symmetric, keep-alive is the +weakest option and close is the strongest. + + Backend mode + + | KAL | SCL | CLO + ----+-----+-----+---- + KAL | KAL | SCL | CLO + ----+-----+-----+---- + mode SCL | SCL | SCL | CLO + ----+-----+-----+---- + CLO | CLO | CLO | CLO + +It is possible to chain a TCP frontend to an HTTP backend. It is pointless if +only HTTP traffic is handled. But it may be used to handle several protocols +within the same frontend. In this case, the client's connection is first handled +as a raw tcp connection before being upgraded to HTTP. Before the upgrade, the +content processings are performend on raw data. Once upgraded, data is parsed +and stored using an internal representation called HTX and it is no longer +possible to rely on raw representation. There is no way to go back. + +There are two kind of upgrades, in-place upgrades and destructive upgrades. The +first ones involves a TCP to HTTP/1 upgrade. In HTTP/1, the request +processings are serialized, thus the applicative stream can be preserved. The +second one involves a TCP to HTTP/2 upgrade. Because it is a multiplexed +protocol, the applicative stream cannot be associated to any HTTP/2 stream and +is destroyed. New applicative streams are then created when HAProxy receives +new HTTP/2 streams at the lower level, in the H2 multiplexer. It is important +to understand this difference because that drastically changes the way to +process data. When an HTTP/1 upgrade is performed, the content processings +already performed on raw data are neither lost nor reexecuted while for an +HTTP/2 upgrade, applicative streams are distinct and all frontend rules are +evaluated systematically on each one. And as said, the first stream, the TCP +one, is destroyed, but only after the frontend rules were evaluated. + +There is another importnat point to understand when HTTP processings are +performed from a TCP proxy. While HAProxy is able to parse HTTP/1 in-fly from +tcp-request content rules, it is not possible for HTTP/2. Only the HTTP/2 +preface can be parsed. This is a huge limitation regarding the HTTP content +analysis in TCP. Concretely it is only possible to know if received data are +HTTP. For instance, it is not possible to choose a backend based on the Host +header value while it is trivial in HTTP/1. Hopefully, there is a solution to +mitigate this drawback. + +There are two ways to perform an HTTP upgrade. The first one, the historical +method, is to select an HTTP backend. The upgrade happens when the backend is +set. Thus, for in-place upgrades, only the backend configuration is considered +in the HTTP data processing. For destructive upgrades, the applicative stream +is destroyed, thus its processing is stopped. With this method, possibilities +to choose a backend with an HTTP/2 connection are really limited, as mentioned +above, and a bit useless because the stream is destroyed. The second method is +to upgrade during the tcp-request content rules evaluation, thanks to the +"switch-mode http" action. In this case, the upgrade is performed in the +frontend context and it is possible to define HTTP directives in this +frontend. For in-place upgrades, it offers all the power of the HTTP analysis +as soon as possible. It is not that far from an HTTP frontend. For destructive +upgrades, it does not change anything except it is useless to choose a backend +on limited information. It is of course the recommended method. Thus, testing +the request protocol from the tcp-request content rules to perform an HTTP +upgrade is enough. All the remaining HTTP manipulation may be moved to the +frontend http-request ruleset. But keep in mind that tcp-request content rules +remains evaluated on each streams, that can't be changed. + +4.1. Proxy keywords matrix +-------------------------- + +The following list of keywords is supported. Most of them may only be used in a +limited set of section types. Some of them are marked as "deprecated" because +they are inherited from an old syntax which may be confusing or functionally +limited, and there are new recommended keywords to replace them. Keywords +marked with "(*)" can be optionally inverted using the "no" prefix, e.g. "no +option contstats". This makes sense when the option has been enabled by default +and must be disabled for a specific instance. Such options may also be prefixed +with "default" in order to restore default settings regardless of what has been +specified in a previous "defaults" section. Keywords supported in defaults +sections marked with "(!)" are only supported in named defaults sections, not +anonymous ones. + + + keyword defaults frontend listen backend +------------------------------------+----------+----------+---------+--------- +acl X (!) X X X +backlog X X X - +balance X - X X +bind - X X - +bind-process X X X X +capture cookie - X X - +capture request header - X X - +capture response header - X X - +clitcpka-cnt X X X - +clitcpka-idle X X X - +clitcpka-intvl X X X - +compression X X X X +cookie X - X X +declare capture - X X - +default-server X - X X +default_backend X X X - +description - X X X +disabled X X X X +dispatch - - X X +email-alert from X X X X +email-alert level X X X X +email-alert mailers X X X X +email-alert myhostname X X X X +email-alert to X X X X +enabled X X X X +errorfile X X X X +errorfiles X X X X +errorloc X X X X +errorloc302 X X X X +-- keyword -------------------------- defaults - frontend - listen -- backend - +errorloc303 X X X X +error-log-format X X X - +force-persist - - X X +filter - X X X +fullconn X - X X +hash-type X - X X +http-after-response X (!) X X X +http-check comment X - X X +http-check connect X - X X +http-check disable-on-404 X - X X +http-check expect X - X X +http-check send X - X X +http-check send-state X - X X +http-check set-var X - X X +http-check unset-var X - X X +http-error X X X X +http-request X (!) X X X +http-response X (!) X X X +http-reuse X - X X +http-send-name-header X - X X +id - X X X +ignore-persist - - X X +load-server-state-from-file X - X X +log (*) X X X X +log-format X X X - +log-format-sd X X X - +log-tag X X X X +max-keep-alive-queue X - X X +maxconn X X X - +mode X X X X +monitor fail - X X - +monitor-uri X X X - +option abortonclose (*) X - X X +option accept-invalid-http-request (*) X X X - +option accept-invalid-http-response (*) X - X X +option allbackups (*) X - X X +option checkcache (*) X - X X +option clitcpka (*) X X X - +option contstats (*) X X X - +option disable-h2-upgrade (*) X X X - +option dontlog-normal (*) X X X - +option dontlognull (*) X X X - +-- keyword -------------------------- defaults - frontend - listen -- backend - +option forwardfor X X X X +option h1-case-adjust-bogus-client (*) X X X - +option h1-case-adjust-bogus-server (*) X - X X +option http-buffer-request (*) X X X X +option http-ignore-probes (*) X X X - +option http-keep-alive (*) X X X X +option http-no-delay (*) X X X X +option http-pretend-keepalive (*) X - X X +option http-restrict-req-hdr-names X X X X +option http-server-close (*) X X X X +option http-use-proxy-header (*) X X X - +option httpchk X - X X +option httpclose (*) X X X X +option httplog X X X - +option httpslog X X X - +option independent-streams (*) X X X X +option ldap-check X - X X +option external-check X - X X +option log-health-checks (*) X - X X +option log-separate-errors (*) X X X - +option logasap (*) X X X - +option mysql-check X - X X +option nolinger (*) X X X X +option originalto X X X X +option persist (*) X - X X +option pgsql-check X - X X +option prefer-last-server (*) X - X X +option redispatch (*) X - X X +option redis-check X - X X +option smtpchk X - X X +option socket-stats (*) X X X - +option splice-auto (*) X X X X +option splice-request (*) X X X X +option splice-response (*) X X X X +option spop-check X - X X +option srvtcpka (*) X - X X +option ssl-hello-chk X - X X +-- keyword -------------------------- defaults - frontend - listen -- backend - +option tcp-check X - X X +option tcp-smart-accept (*) X X X - +option tcp-smart-connect (*) X - X X +option tcpka X X X X +option tcplog X X X X +option transparent (*) X - X X +option idle-close-on-response (*) X X X - +external-check command X - X X +external-check path X - X X +persist rdp-cookie X - X X +rate-limit sessions X X X - +redirect - X X X +-- keyword -------------------------- defaults - frontend - listen -- backend - +retries X - X X +retry-on X - X X +server - - X X +server-state-file-name X - X X +server-template - - X X +source X - X X +srvtcpka-cnt X - X X +srvtcpka-idle X - X X +srvtcpka-intvl X - X X +stats admin - X X X +stats auth X X X X +stats enable X X X X +stats hide-version X X X X +stats http-request - X X X +stats realm X X X X +stats refresh X X X X +stats scope X X X X +stats show-desc X X X X +stats show-legends X X X X +stats show-node X X X X +stats uri X X X X +-- keyword -------------------------- defaults - frontend - listen -- backend - +stick match - - X X +stick on - - X X +stick store-request - - X X +stick store-response - - X X +stick-table - X X X +tcp-check comment X - X X +tcp-check connect X - X X +tcp-check expect X - X X +tcp-check send X - X X +tcp-check send-lf X - X X +tcp-check send-binary X - X X +tcp-check send-binary-lf X - X X +tcp-check set-var X - X X +tcp-check unset-var X - X X +tcp-request connection X (!) X X - +tcp-request content X (!) X X X +tcp-request inspect-delay X (!) X X X +tcp-request session X (!) X X - +tcp-response content X (!) - X X +tcp-response inspect-delay X (!) - X X +timeout check X - X X +timeout client X X X - +timeout client-fin X X X - +timeout connect X - X X +timeout http-keep-alive X X X X +timeout http-request X X X X +timeout queue X - X X +timeout server X - X X +timeout server-fin X - X X +timeout tarpit X X X X +timeout tunnel X - X X +transparent (deprecated) X - X X +unique-id-format X X X - +unique-id-header X X X - +use_backend - X X - +use-fcgi-app - - X X +use-server - - X X +------------------------------------+----------+----------+---------+--------- + keyword defaults frontend listen backend + + +4.2. Alphabetically sorted keywords reference +--------------------------------------------- + +This section provides a description of each keyword and its usage. + + +acl <aclname> <criterion> [flags] [operator] <value> ... + Declare or complete an access list. + May be used in sections : defaults | frontend | listen | backend + yes(!) | yes | yes | yes + + This directive is only available from named defaults sections, not anonymous + ones. ACLs defined in a defaults section are not visible from other sections + using it. + + Example: + acl invalid_src src 0.0.0.0/7 224.0.0.0/3 + acl invalid_src src_port 0:1023 + acl local_dst hdr(host) -i localhost + + See section 7 about ACL usage. + + +backlog <conns> + Give hints to the system about the approximate listen backlog desired size + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : + <conns> is the number of pending connections. Depending on the operating + system, it may represent the number of already acknowledged + connections, of non-acknowledged ones, or both. + + In order to protect against SYN flood attacks, one solution is to increase + the system's SYN backlog size. Depending on the system, sometimes it is just + tunable via a system parameter, sometimes it is not adjustable at all, and + sometimes the system relies on hints given by the application at the time of + the listen() syscall. By default, HAProxy passes the frontend's maxconn value + to the listen() syscall. On systems which can make use of this value, it can + sometimes be useful to be able to specify a different value, hence this + backlog parameter. + + On Linux 2.4, the parameter is ignored by the system. On Linux 2.6, it is + used as a hint and the system accepts up to the smallest greater power of + two, and never more than some limits (usually 32768). + + See also : "maxconn" and the target operating system's tuning guide. + + +balance <algorithm> [ <arguments> ] +balance url_param <param> [check_post] + Define the load balancing algorithm to be used in a backend. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <algorithm> is the algorithm used to select a server when doing load + balancing. This only applies when no persistence information + is available, or when a connection is redispatched to another + server. <algorithm> may be one of the following : + + roundrobin Each server is used in turns, according to their weights. + This is the smoothest and fairest algorithm when the server's + processing time remains equally distributed. This algorithm + is dynamic, which means that server weights may be adjusted + on the fly for slow starts for instance. It is limited by + design to 4095 active servers per backend. Note that in some + large farms, when a server becomes up after having been down + for a very short time, it may sometimes take a few hundreds + requests for it to be re-integrated into the farm and start + receiving traffic. This is normal, though very rare. It is + indicated here in case you would have the chance to observe + it, so that you don't worry. + + static-rr Each server is used in turns, according to their weights. + This algorithm is as similar to roundrobin except that it is + static, which means that changing a server's weight on the + fly will have no effect. On the other hand, it has no design + limitation on the number of servers, and when a server goes + up, it is always immediately reintroduced into the farm, once + the full map is recomputed. It also uses slightly less CPU to + run (around -1%). + + leastconn The server with the lowest number of connections receives the + connection. Round-robin is performed within groups of servers + of the same load to ensure that all servers will be used. Use + of this algorithm is recommended where very long sessions are + expected, such as LDAP, SQL, TSE, etc... but is not very well + suited for protocols using short sessions such as HTTP. This + algorithm is dynamic, which means that server weights may be + adjusted on the fly for slow starts for instance. It will + also consider the number of queued connections in addition to + the established ones in order to minimize queuing. + + first The first server with available connection slots receives the + connection. The servers are chosen from the lowest numeric + identifier to the highest (see server parameter "id"), which + defaults to the server's position in the farm. Once a server + reaches its maxconn value, the next server is used. It does + not make sense to use this algorithm without setting maxconn. + The purpose of this algorithm is to always use the smallest + number of servers so that extra servers can be powered off + during non-intensive hours. This algorithm ignores the server + weight, and brings more benefit to long session such as RDP + or IMAP than HTTP, though it can be useful there too. In + order to use this algorithm efficiently, it is recommended + that a cloud controller regularly checks server usage to turn + them off when unused, and regularly checks backend queue to + turn new servers on when the queue inflates. Alternatively, + using "http-check send-state" may inform servers on the load. + + hash Takes a regular sample expression in argument. The expression + is evaluated for each request and hashed according to the + configured hash-type. The result of the hash is divided by + the total weight of the running servers to designate which + server will receive the request. This can be used in place of + "source", "uri", "hdr()", "url_param()", "rdp-cookie" to make + use of a converter, refine the evaluation, or be used to + extract data from local variables for example. When the data + is not available, round robin will apply. This algorithm is + static by default, which means that changing a server's + weight on the fly will have no effect, but this can be + changed using "hash-type". + + source The source IP address is hashed and divided by the total + weight of the running servers to designate which server will + receive the request. This ensures that the same client IP + address will always reach the same server as long as no + server goes down or up. If the hash result changes due to the + number of running servers changing, many clients will be + directed to a different server. This algorithm is generally + used in TCP mode where no cookie may be inserted. It may also + be used on the Internet to provide a best-effort stickiness + to clients which refuse session cookies. This algorithm is + static by default, which means that changing a server's + weight on the fly will have no effect, but this can be + changed using "hash-type". See also the "hash" option above. + + uri This algorithm hashes either the left part of the URI (before + the question mark) or the whole URI (if the "whole" parameter + is present) and divides the hash value by the total weight of + the running servers. The result designates which server will + receive the request. This ensures that the same URI will + always be directed to the same server as long as no server + goes up or down. This is used with proxy caches and + anti-virus proxies in order to maximize the cache hit rate. + Note that this algorithm may only be used in an HTTP backend. + This algorithm is static by default, which means that + changing a server's weight on the fly will have no effect, + but this can be changed using "hash-type". + + This algorithm supports two optional parameters "len" and + "depth", both followed by a positive integer number. These + options may be helpful when it is needed to balance servers + based on the beginning of the URI only. The "len" parameter + indicates that the algorithm should only consider that many + characters at the beginning of the URI to compute the hash. + Note that having "len" set to 1 rarely makes sense since most + URIs start with a leading "/". + + The "depth" parameter indicates the maximum directory depth + to be used to compute the hash. One level is counted for each + slash in the request. If both parameters are specified, the + evaluation stops when either is reached. + + A "path-only" parameter indicates that the hashing key starts + at the first '/' of the path. This can be used to ignore the + authority part of absolute URIs, and to make sure that HTTP/1 + and HTTP/2 URIs will provide the same hash. See also the + "hash" option above. + + url_param The URL parameter specified in argument will be looked up in + the query string of each HTTP GET request. + + If the modifier "check_post" is used, then an HTTP POST + request entity will be searched for the parameter argument, + when it is not found in a query string after a question mark + ('?') in the URL. The message body will only start to be + analyzed once either the advertised amount of data has been + received or the request buffer is full. In the unlikely event + that chunked encoding is used, only the first chunk is + scanned. Parameter values separated by a chunk boundary, may + be randomly balanced if at all. This keyword used to support + an optional <max_wait> parameter which is now ignored. + + If the parameter is found followed by an equal sign ('=') and + a value, then the value is hashed and divided by the total + weight of the running servers. The result designates which + server will receive the request. + + This is used to track user identifiers in requests and ensure + that a same user ID will always be sent to the same server as + long as no server goes up or down. If no value is found or if + the parameter is not found, then a round robin algorithm is + applied. Note that this algorithm may only be used in an HTTP + backend. This algorithm is static by default, which means + that changing a server's weight on the fly will have no + effect, but this can be changed using "hash-type". See also + the "hash" option above. + + hdr(<name>) The HTTP header <name> will be looked up in each HTTP + request. Just as with the equivalent ACL 'hdr()' function, + the header name in parenthesis is not case sensitive. If the + header is absent or if it does not contain any value, the + roundrobin algorithm is applied instead. + + An optional 'use_domain_only' parameter is available, for + reducing the hash algorithm to the main domain part with some + specific headers such as 'Host'. For instance, in the Host + value "haproxy.1wt.eu", only "1wt" will be considered. + + This algorithm is static by default, which means that + changing a server's weight on the fly will have no effect, + but this can be changed using "hash-type". See also the + "hash" option above. + + random + random(<draws>) + A random number will be used as the key for the consistent + hashing function. This means that the servers' weights are + respected, dynamic weight changes immediately take effect, as + well as new server additions. Random load balancing can be + useful with large farms or when servers are frequently added + or removed as it may avoid the hammering effect that could + result from roundrobin or leastconn in this situation. The + hash-balance-factor directive can be used to further improve + fairness of the load balancing, especially in situations + where servers show highly variable response times. When an + argument <draws> is present, it must be an integer value one + or greater, indicating the number of draws before selecting + the least loaded of these servers. It was indeed demonstrated + that picking the least loaded of two servers is enough to + significantly improve the fairness of the algorithm, by + always avoiding to pick the most loaded server within a farm + and getting rid of any bias that could be induced by the + unfair distribution of the consistent list. Higher values N + will take away N-1 of the highest loaded servers at the + expense of performance. With very high values, the algorithm + will converge towards the leastconn's result but much slower. + The default value is 2, which generally shows very good + distribution and performance. This algorithm is also known as + the Power of Two Random Choices and is described here : + http://www.eecs.harvard.edu/~michaelm/postscripts/handbook2001.pdf + + rdp-cookie + rdp-cookie(<name>) + The RDP cookie <name> (or "mstshash" if omitted) will be + looked up and hashed for each incoming TCP request. Just as + with the equivalent ACL 'req.rdp_cookie()' function, the name + is not case-sensitive. This mechanism is useful as a degraded + persistence mode, as it makes it possible to always send the + same user (or the same session ID) to the same server. If the + cookie is not found, the normal roundrobin algorithm is + used instead. + + Note that for this to work, the frontend must ensure that an + RDP cookie is already present in the request buffer. For this + you must use 'tcp-request content accept' rule combined with + a 'req.rdp_cookie_cnt' ACL. + + This algorithm is static by default, which means that + changing a server's weight on the fly will have no effect, + but this can be changed using "hash-type". See also the + "hash" option above. + + <arguments> is an optional list of arguments which may be needed by some + algorithms. Right now, only "url_param" and "uri" support an + optional argument. + + The load balancing algorithm of a backend is set to roundrobin when no other + algorithm, mode nor option have been set. The algorithm may only be set once + for each backend. + + With authentication schemes that require the same connection like NTLM, URI + based algorithms must not be used, as they would cause subsequent requests + to be routed to different backend servers, breaking the invalid assumptions + NTLM relies on. + + Examples : + balance roundrobin + balance url_param userid + balance url_param session_id check_post 64 + balance hdr(User-Agent) + balance hdr(host) + balance hdr(Host) use_domain_only + balance hash req.cookie(clientid) + balance hash var(req.client_id) + balance hash req.hdr_ip(x-forwarded-for,-1),ipmask(24) + + Note: the following caveats and limitations on using the "check_post" + extension with "url_param" must be considered : + + - all POST requests are eligible for consideration, because there is no way + to determine if the parameters will be found in the body or entity which + may contain binary data. Therefore another method may be required to + restrict consideration of POST requests that have no URL parameters in + the body. (see acl http_end) + + - using a <max_wait> value larger than the request buffer size does not + make sense and is useless. The buffer size is set at build time, and + defaults to 16 kB. + + - Content-Encoding is not supported, the parameter search will probably + fail; and load balancing will fall back to Round Robin. + + - Expect: 100-continue is not supported, load balancing will fall back to + Round Robin. + + - Transfer-Encoding (RFC7230 3.3.1) is only supported in the first chunk. + If the entire parameter value is not present in the first chunk, the + selection of server is undefined (actually, defined by how little + actually appeared in the first chunk). + + - This feature does not support generation of a 100, 411 or 501 response. + + - In some cases, requesting "check_post" MAY attempt to scan the entire + contents of a message body. Scanning normally terminates when linear + white space or control characters are found, indicating the end of what + might be a URL parameter list. This is probably not a concern with SGML + type message bodies. + + See also : "dispatch", "cookie", "transparent", "hash-type". + + +bind [<address>]:<port_range> [, ...] [param*] +bind /<path> [, ...] [param*] + Define one or several listening addresses and/or ports in a frontend. + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | no + Arguments : + <address> is optional and can be a host name, an IPv4 address, an IPv6 + address, or '*'. It designates the address the frontend will + listen on. If unset, all IPv4 addresses of the system will be + listened on. The same will apply for '*' or the system's + special address "0.0.0.0". The IPv6 equivalent is '::'. Note + that if you bind a frontend to multiple UDP addresses you have + no guarantee about the address which will be used to respond. + This is why "0.0.0.0" addresses and lists of comma-separated + IP addresses have been forbidden to bind QUIC addresses. + Optionally, an address family prefix may be used before the + address to force the family regardless of the address format, + which can be useful to specify a path to a unix socket with + no slash ('/'). Currently supported prefixes are : + - 'ipv4@' -> address is always IPv4 + - 'ipv6@' -> address is always IPv6 + - 'udp@' -> address is resolved as IPv4 or IPv6 and + protocol UDP is used. Currently those listeners are + supported only in log-forward sections. + - 'udp4@' -> address is always IPv4 and protocol UDP + is used. Currently those listeners are supported + only in log-forward sections. + - 'udp6@' -> address is always IPv6 and protocol UDP + is used. Currently those listeners are supported + only in log-forward sections. + - 'unix@' -> address is a path to a local unix socket + - 'abns@' -> address is in abstract namespace (Linux only). + - 'fd@<n>' -> use file descriptor <n> inherited from the + parent. The fd must be bound and may or may not already + be listening. + - 'sockpair@<n>'-> like fd@ but you must use the fd of a + connected unix socket or of a socketpair. The bind waits + to receive a FD over the unix socket and uses it as if it + was the FD of an accept(). Should be used carefully. + - 'quic4@' -> address is resolved as IPv4 and protocol UDP + is used. Note that QUIC connections attached to a + listener will be multiplexed over the listener socket. + With a large traffic this has a noticeable impact on + performance and CPU consumption. To improve this, you + should duplicate QUIC listener instances over several + threads, for example using "shards" keyword. + - 'quic6@' -> address is resolved as IPv6 and protocol UDP + is used. The performance note for QUIC over IPv4 applies + as well. + + You may want to reference some environment variables in the + address parameter, see section 2.3 about environment + variables. + + <port_range> is either a unique TCP port, or a port range for which the + proxy will accept connections for the IP address specified + above. The port is mandatory for TCP listeners. Note that in + the case of an IPv6 address, the port is always the number + after the last colon (':'). A range can either be : + - a numerical port (ex: '80') + - a dash-delimited ports range explicitly stating the lower + and upper bounds (ex: '2000-2100') which are included in + the range. + + Particular care must be taken against port ranges, because + every <address:port> couple consumes one socket (= a file + descriptor), so it's easy to consume lots of descriptors + with a simple range, and to run out of sockets. Also, each + <address:port> couple must be used only once among all + instances running on a same system. Please note that binding + to ports lower than 1024 generally require particular + privileges to start the program, which are independent of + the 'uid' parameter. + + <path> is a UNIX socket path beginning with a slash ('/'). This is + alternative to the TCP listening port. HAProxy will then + receive UNIX connections on the socket located at this place. + The path must begin with a slash and by default is absolute. + It can be relative to the prefix defined by "unix-bind" in + the global section. Note that the total length of the prefix + followed by the socket path cannot exceed some system limits + for UNIX sockets, which commonly are set to 107 characters. + + <param*> is a list of parameters common to all sockets declared on the + same line. These numerous parameters depend on OS and build + options and have a complete section dedicated to them. Please + refer to section 5 to for more details. + + It is possible to specify a list of address:port combinations delimited by + commas. The frontend will then listen on all of these addresses. There is no + fixed limit to the number of addresses and ports which can be listened on in + a frontend, as well as there is no limit to the number of "bind" statements + in a frontend. + + Example : + listen http_proxy + bind :80,:443 + bind 10.0.0.1:10080,10.0.0.1:10443 + bind /var/run/ssl-frontend.sock user root mode 600 accept-proxy + + listen http_https_proxy + bind :80 + bind :443 ssl crt /etc/haproxy/site.pem + + listen http_https_proxy_explicit + bind ipv6@:80 + bind ipv4@public_ssl:443 ssl crt /etc/haproxy/site.pem + bind unix@ssl-frontend.sock user root mode 600 accept-proxy + + listen external_bind_app1 + bind "fd@${FD_APP1}" + + listen h3_quic_proxy + bind quic4@10.0.0.1:8888 ssl crt /etc/mycrt alpn h3 + + Note: regarding Linux's abstract namespace sockets, HAProxy uses the whole + sun_path length is used for the address length. Some other programs + such as socat use the string length only by default. Pass the option + ",unix-tightsocklen=0" to any abstract socket definition in socat to + make it compatible with HAProxy's. + + See also : "source", "option forwardfor", "unix-bind" and the PROXY protocol + documentation, and section 5 about bind options. + + +bind-process [ all | odd | even | <process_num>[-[<process_num>]] ] ... + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + + Deprecated. Before threads were supported, this was used to force some + frontends on certain processes only, or to adjust backends so that they + could match the frontends that used them. The default and only accepted + value is "1" (along with "all" and "odd" which alias it). Do not use this + setting. Threads can still be bound per-socket using the "process" bind + keyword. + + See also : "process" in section 5.1. + + +capture cookie <name> len <length> + Capture and log a cookie in the request and in the response. + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | no + Arguments : + <name> is the beginning of the name of the cookie to capture. In order + to match the exact name, simply suffix the name with an equal + sign ('='). The full name will appear in the logs, which is + useful with application servers which adjust both the cookie name + and value (e.g. ASPSESSIONXXX). + + <length> is the maximum number of characters to report in the logs, which + include the cookie name, the equal sign and the value, all in the + standard "name=value" form. The string will be truncated on the + right if it exceeds <length>. + + Only the first cookie is captured. Both the "cookie" request headers and the + "set-cookie" response headers are monitored. This is particularly useful to + check for application bugs causing session crossing or stealing between + users, because generally the user's cookies can only change on a login page. + + When the cookie was not presented by the client, the associated log column + will report "-". When a request does not cause a cookie to be assigned by the + server, a "-" is reported in the response column. + + The capture is performed in the frontend only because it is necessary that + the log format does not change for a given frontend depending on the + backends. This may change in the future. Note that there can be only one + "capture cookie" statement in a frontend. The maximum capture length is set + by the global "tune.http.cookielen" setting and defaults to 63 characters. It + is not possible to specify a capture in a "defaults" section. + + Example: + capture cookie ASPSESSION len 32 + + See also : "capture request header", "capture response header" as well as + section 8 about logging. + + +capture request header <name> len <length> + Capture and log the last occurrence of the specified request header. + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | no + Arguments : + <name> is the name of the header to capture. The header names are not + case-sensitive, but it is a common practice to write them as they + appear in the requests, with the first letter of each word in + upper case. The header name will not appear in the logs, only the + value is reported, but the position in the logs is respected. + + <length> is the maximum number of characters to extract from the value and + report in the logs. The string will be truncated on the right if + it exceeds <length>. + + The complete value of the last occurrence of the header is captured. The + value will be added to the logs between braces ('{}'). If multiple headers + are captured, they will be delimited by a vertical bar ('|') and will appear + in the same order they were declared in the configuration. Non-existent + headers will be logged just as an empty string. Common uses for request + header captures include the "Host" field in virtual hosting environments, the + "Content-length" when uploads are supported, "User-agent" to quickly + differentiate between real users and robots, and "X-Forwarded-For" in proxied + environments to find where the request came from. + + Note that when capturing headers such as "User-agent", some spaces may be + logged, making the log analysis more difficult. Thus be careful about what + you log if you know your log parser is not smart enough to rely on the + braces. + + There is no limit to the number of captured request headers nor to their + length, though it is wise to keep them low to limit memory usage per session. + In order to keep log format consistent for a same frontend, header captures + can only be declared in a frontend. It is not possible to specify a capture + in a "defaults" section. + + Example: + capture request header Host len 15 + capture request header X-Forwarded-For len 15 + capture request header Referer len 15 + + See also : "capture cookie", "capture response header" as well as section 8 + about logging. + + +capture response header <name> len <length> + Capture and log the last occurrence of the specified response header. + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | no + Arguments : + <name> is the name of the header to capture. The header names are not + case-sensitive, but it is a common practice to write them as they + appear in the response, with the first letter of each word in + upper case. The header name will not appear in the logs, only the + value is reported, but the position in the logs is respected. + + <length> is the maximum number of characters to extract from the value and + report in the logs. The string will be truncated on the right if + it exceeds <length>. + + The complete value of the last occurrence of the header is captured. The + result will be added to the logs between braces ('{}') after the captured + request headers. If multiple headers are captured, they will be delimited by + a vertical bar ('|') and will appear in the same order they were declared in + the configuration. Non-existent headers will be logged just as an empty + string. Common uses for response header captures include the "Content-length" + header which indicates how many bytes are expected to be returned, the + "Location" header to track redirections. + + There is no limit to the number of captured response headers nor to their + length, though it is wise to keep them low to limit memory usage per session. + In order to keep log format consistent for a same frontend, header captures + can only be declared in a frontend. It is not possible to specify a capture + in a "defaults" section. + + Example: + capture response header Content-length len 9 + capture response header Location len 15 + + See also : "capture cookie", "capture request header" as well as section 8 + about logging. + + +clitcpka-cnt <count> + Sets the maximum number of keepalive probes TCP should send before dropping + the connection on the client side. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : + <count> is the maximum number of keepalive probes. + + This keyword corresponds to the socket option TCP_KEEPCNT. If this keyword + is not specified, system-wide TCP parameter (tcp_keepalive_probes) is used. + The availability of this setting depends on the operating system. It is + known to work on Linux. + + See also : "option clitcpka", "clitcpka-idle", "clitcpka-intvl". + + +clitcpka-idle <timeout> + Sets the time the connection needs to remain idle before TCP starts sending + keepalive probes, if enabled the sending of TCP keepalive packets on the + client side. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : + <timeout> is the time the connection needs to remain idle before TCP starts + sending keepalive probes. It is specified in seconds by default, + but can be in any other unit if the number is suffixed by the + unit, as explained at the top of this document. + + This keyword corresponds to the socket option TCP_KEEPIDLE. If this keyword + is not specified, system-wide TCP parameter (tcp_keepalive_time) is used. + The availability of this setting depends on the operating system. It is + known to work on Linux. + + See also : "option clitcpka", "clitcpka-cnt", "clitcpka-intvl". + + +clitcpka-intvl <timeout> + Sets the time between individual keepalive probes on the client side. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : + <timeout> is the time between individual keepalive probes. It is specified + in seconds by default, but can be in any other unit if the number + is suffixed by the unit, as explained at the top of this + document. + + This keyword corresponds to the socket option TCP_KEEPINTVL. If this keyword + is not specified, system-wide TCP parameter (tcp_keepalive_intvl) is used. + The availability of this setting depends on the operating system. It is + known to work on Linux. + + See also : "option clitcpka", "clitcpka-cnt", "clitcpka-idle". + + +compression algo <algorithm> ... +compression type <mime type> ... + Enable HTTP compression. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + algo is followed by the list of supported compression algorithms. + type is followed by the list of MIME types that will be compressed. + + The currently supported algorithms are : + identity this is mostly for debugging, and it was useful for developing + the compression feature. Identity does not apply any change on + data. + + gzip applies gzip compression. This setting is only available when + support for zlib or libslz was built in. + + deflate same as "gzip", but with deflate algorithm and zlib format. + Note that this algorithm has ambiguous support on many + browsers and no support at all from recent ones. It is + strongly recommended not to use it for anything else than + experimentation. This setting is only available when support + for zlib or libslz was built in. + + raw-deflate same as "deflate" without the zlib wrapper, and used as an + alternative when the browser wants "deflate". All major + browsers understand it and despite violating the standards, + it is known to work better than "deflate", at least on MSIE + and some versions of Safari. Do not use it in conjunction + with "deflate", use either one or the other since both react + to the same Accept-Encoding token. This setting is only + available when support for zlib or libslz was built in. + + Compression will be activated depending on the Accept-Encoding request + header. With identity, it does not take care of that header. + If backend servers support HTTP compression, these directives + will be no-op: HAProxy will see the compressed response and will not + compress again. If backend servers do not support HTTP compression and + there is Accept-Encoding header in request, HAProxy will compress the + matching response. + + Compression is disabled when: + * the request does not advertise a supported compression algorithm in the + "Accept-Encoding" header + * the response message is not HTTP/1.1 or above + * HTTP status code is not one of 200, 201, 202, or 203 + * response contain neither a "Content-Length" header nor a + "Transfer-Encoding" whose last value is "chunked" + * response contains a "Content-Type" header whose first value starts with + "multipart" + * the response contains the "no-transform" value in the "Cache-control" + header + * User-Agent matches "Mozilla/4" unless it is MSIE 6 with XP SP2, or MSIE 7 + and later + * The response contains a "Content-Encoding" header, indicating that the + response is already compressed (see compression offload) + * The response contains an invalid "ETag" header or multiple ETag headers + + Note: The compression does not emit the Warning header. + + Examples : + compression algo gzip + compression type text/html text/plain + + See also : "compression offload" + +compression offload + Makes HAProxy work as a compression offloader only. + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | yes + + The "offload" setting makes HAProxy remove the Accept-Encoding header to + prevent backend servers from compressing responses. It is strongly + recommended not to do this because this means that all the compression work + will be done on the single point where HAProxy is located. However in some + deployment scenarios, HAProxy may be installed in front of a buggy gateway + with broken HTTP compression implementation which can't be turned off. + In that case HAProxy can be used to prevent that gateway from emitting + invalid payloads. In this case, simply removing the header in the + configuration does not work because it applies before the header is parsed, + so that prevents HAProxy from compressing. The "offload" setting should + then be used for such scenarios. + + If this setting is used in a defaults section, a warning is emitted and the + option is ignored. + + See also : "compression type", "compression algo" + +cookie <name> [ rewrite | insert | prefix ] [ indirect ] [ nocache ] + [ postonly ] [ preserve ] [ httponly ] [ secure ] + [ domain <domain> ]* [ maxidle <idle> ] [ maxlife <life> ] + [ dynamic ] [ attr <value> ]* + Enable cookie-based persistence in a backend. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <name> is the name of the cookie which will be monitored, modified or + inserted in order to bring persistence. This cookie is sent to + the client via a "Set-Cookie" header in the response, and is + brought back by the client in a "Cookie" header in all requests. + Special care should be taken to choose a name which does not + conflict with any likely application cookie. Also, if the same + backends are subject to be used by the same clients (e.g. + HTTP/HTTPS), care should be taken to use different cookie names + between all backends if persistence between them is not desired. + + rewrite This keyword indicates that the cookie will be provided by the + server and that HAProxy will have to modify its value to set the + server's identifier in it. This mode is handy when the management + of complex combinations of "Set-cookie" and "Cache-control" + headers is left to the application. The application can then + decide whether or not it is appropriate to emit a persistence + cookie. Since all responses should be monitored, this mode + doesn't work in HTTP tunnel mode. Unless the application + behavior is very complex and/or broken, it is advised not to + start with this mode for new deployments. This keyword is + incompatible with "insert" and "prefix". + + insert This keyword indicates that the persistence cookie will have to + be inserted by HAProxy in server responses if the client did not + + already have a cookie that would have permitted it to access this + server. When used without the "preserve" option, if the server + emits a cookie with the same name, it will be removed before + processing. For this reason, this mode can be used to upgrade + existing configurations running in the "rewrite" mode. The cookie + will only be a session cookie and will not be stored on the + client's disk. By default, unless the "indirect" option is added, + the server will see the cookies emitted by the client. Due to + caching effects, it is generally wise to add the "nocache" or + "postonly" keywords (see below). The "insert" keyword is not + compatible with "rewrite" and "prefix". + + prefix This keyword indicates that instead of relying on a dedicated + cookie for the persistence, an existing one will be completed. + This may be needed in some specific environments where the client + does not support more than one single cookie and the application + already needs it. In this case, whenever the server sets a cookie + named <name>, it will be prefixed with the server's identifier + and a delimiter. The prefix will be removed from all client + requests so that the server still finds the cookie it emitted. + Since all requests and responses are subject to being modified, + this mode doesn't work with tunnel mode. The "prefix" keyword is + not compatible with "rewrite" and "insert". Note: it is highly + recommended not to use "indirect" with "prefix", otherwise server + cookie updates would not be sent to clients. + + indirect When this option is specified, no cookie will be emitted to a + client which already has a valid one for the server which has + processed the request. If the server sets such a cookie itself, + it will be removed, unless the "preserve" option is also set. In + "insert" mode, this will additionally remove cookies from the + requests transmitted to the server, making the persistence + mechanism totally transparent from an application point of view. + Note: it is highly recommended not to use "indirect" with + "prefix", otherwise server cookie updates would not be sent to + clients. + + nocache This option is recommended in conjunction with the insert mode + when there is a cache between the client and HAProxy, as it + ensures that a cacheable response will be tagged non-cacheable if + a cookie needs to be inserted. This is important because if all + persistence cookies are added on a cacheable home page for + instance, then all customers will then fetch the page from an + outer cache and will all share the same persistence cookie, + leading to one server receiving much more traffic than others. + See also the "insert" and "postonly" options. + + postonly This option ensures that cookie insertion will only be performed + on responses to POST requests. It is an alternative to the + "nocache" option, because POST responses are not cacheable, so + this ensures that the persistence cookie will never get cached. + Since most sites do not need any sort of persistence before the + first POST which generally is a login request, this is a very + efficient method to optimize caching without risking to find a + persistence cookie in the cache. + See also the "insert" and "nocache" options. + + preserve This option may only be used with "insert" and/or "indirect". It + allows the server to emit the persistence cookie itself. In this + case, if a cookie is found in the response, HAProxy will leave it + untouched. This is useful in order to end persistence after a + logout request for instance. For this, the server just has to + emit a cookie with an invalid value (e.g. empty) or with a date in + the past. By combining this mechanism with the "disable-on-404" + check option, it is possible to perform a completely graceful + shutdown because users will definitely leave the server after + they logout. + + httponly This option tells HAProxy to add an "HttpOnly" cookie attribute + when a cookie is inserted. This attribute is used so that a + user agent doesn't share the cookie with non-HTTP components. + Please check RFC6265 for more information on this attribute. + + secure This option tells HAProxy to add a "Secure" cookie attribute when + a cookie is inserted. This attribute is used so that a user agent + never emits this cookie over non-secure channels, which means + that a cookie learned with this flag will be presented only over + SSL/TLS connections. Please check RFC6265 for more information on + this attribute. + + domain This option allows to specify the domain at which a cookie is + inserted. It requires exactly one parameter: a valid domain + name. If the domain begins with a dot, the browser is allowed to + use it for any host ending with that name. It is also possible to + specify several domain names by invoking this option multiple + times. Some browsers might have small limits on the number of + domains, so be careful when doing that. For the record, sending + 10 domains to MSIE 6 or Firefox 2 works as expected. + + maxidle This option allows inserted cookies to be ignored after some idle + time. It only works with insert-mode cookies. When a cookie is + sent to the client, the date this cookie was emitted is sent too. + Upon further presentations of this cookie, if the date is older + than the delay indicated by the parameter (in seconds), it will + be ignored. Otherwise, it will be refreshed if needed when the + response is sent to the client. This is particularly useful to + prevent users who never close their browsers from remaining for + too long on the same server (e.g. after a farm size change). When + this option is set and a cookie has no date, it is always + accepted, but gets refreshed in the response. This maintains the + ability for admins to access their sites. Cookies that have a + date in the future further than 24 hours are ignored. Doing so + lets admins fix timezone issues without risking kicking users off + the site. + + maxlife This option allows inserted cookies to be ignored after some life + time, whether they're in use or not. It only works with insert + mode cookies. When a cookie is first sent to the client, the date + this cookie was emitted is sent too. Upon further presentations + of this cookie, if the date is older than the delay indicated by + the parameter (in seconds), it will be ignored. If the cookie in + the request has no date, it is accepted and a date will be set. + Cookies that have a date in the future further than 24 hours are + ignored. Doing so lets admins fix timezone issues without risking + kicking users off the site. Contrary to maxidle, this value is + not refreshed, only the first visit date counts. Both maxidle and + maxlife may be used at the time. This is particularly useful to + prevent users who never close their browsers from remaining for + too long on the same server (e.g. after a farm size change). This + is stronger than the maxidle method in that it forces a + redispatch after some absolute delay. + + dynamic Activate dynamic cookies. When used, a session cookie is + dynamically created for each server, based on the IP and port + of the server, and a secret key, specified in the + "dynamic-cookie-key" backend directive. + The cookie will be regenerated each time the IP address change, + and is only generated for IPv4/IPv6. + + attr This option tells HAProxy to add an extra attribute when a + cookie is inserted. The attribute value can contain any + characters except control ones or ";". This option may be + repeated. + + There can be only one persistence cookie per HTTP backend, and it can be + declared in a defaults section. The value of the cookie will be the value + indicated after the "cookie" keyword in a "server" statement. If no cookie + is declared for a given server, the cookie is not set. + + Examples : + cookie JSESSIONID prefix + cookie SRV insert indirect nocache + cookie SRV insert postonly indirect + cookie SRV insert indirect nocache maxidle 30m maxlife 8h + + See also : "balance source", "capture cookie", "server" and "ignore-persist". + + +declare capture [ request | response ] len <length> + Declares a capture slot. + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | no + Arguments: + <length> is the length allowed for the capture. + + This declaration is only available in the frontend or listen section, but the + reserved slot can be used in the backends. The "request" keyword allocates a + capture slot for use in the request, and "response" allocates a capture slot + for use in the response. + + See also: "capture-req", "capture-res" (sample converters), + "capture.req.hdr", "capture.res.hdr" (sample fetches), + "http-request capture" and "http-response capture". + + +default-server [param*] + Change default options for a server in a backend + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments: + <param*> is a list of parameters for this server. The "default-server" + keyword accepts an important number of options and has a complete + section dedicated to it. Please refer to section 5 for more + details. + + Example : + default-server inter 1000 weight 13 + + See also: "server" and section 5 about server options + + +default_backend <backend> + Specify the backend to use when no "use_backend" rule has been matched. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : + <backend> is the name of the backend to use. + + When doing content-switching between frontend and backends using the + "use_backend" keyword, it is often useful to indicate which backend will be + used when no rule has matched. It generally is the dynamic backend which + will catch all undetermined requests. + + Example : + + use_backend dynamic if url_dyn + use_backend static if url_css url_img extension_img + default_backend dynamic + + See also : "use_backend" + + +description <string> + Describe a listen, frontend or backend. + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | yes + Arguments : string + + Allows to add a sentence to describe the related object in the HAProxy HTML + stats page. The description will be printed on the right of the object name + it describes. + No need to backslash spaces in the <string> arguments. + + +disabled + Disable a proxy, frontend or backend. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + The "disabled" keyword is used to disable an instance, mainly in order to + liberate a listening port or to temporarily disable a service. The instance + will still be created and its configuration will be checked, but it will be + created in the "stopped" state and will appear as such in the statistics. It + will not receive any traffic nor will it send any health-checks or logs. It + is possible to disable many instances at once by adding the "disabled" + keyword in a "defaults" section. + + See also : "enabled" + + +dispatch <address>:<port> + Set a default server address + May be used in sections : defaults | frontend | listen | backend + no | no | yes | yes + Arguments : + + <address> is the IPv4 address of the default server. Alternatively, a + resolvable hostname is supported, but this name will be resolved + during start-up. + + <ports> is a mandatory port specification. All connections will be sent + to this port, and it is not permitted to use port offsets as is + possible with normal servers. + + The "dispatch" keyword designates a default server for use when no other + server can take the connection. In the past it was used to forward non + persistent connections to an auxiliary load balancer. Due to its simple + syntax, it has also been used for simple TCP relays. It is recommended not to + use it for more clarity, and to use the "server" directive instead. + + See also : "server" + + +dynamic-cookie-key <string> + Set the dynamic cookie secret key for a backend. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : The secret key to be used. + + When dynamic cookies are enabled (see the "dynamic" directive for cookie), + a dynamic cookie is created for each server (unless one is explicitly + specified on the "server" line), using a hash of the IP address of the + server, the TCP port, and the secret key. + That way, we can ensure session persistence across multiple load-balancers, + even if servers are dynamically added or removed. + +enabled + Enable a proxy, frontend or backend. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + The "enabled" keyword is used to explicitly enable an instance, when the + defaults has been set to "disabled". This is very rarely used. + + See also : "disabled" + + +errorfile <code> <file> + Return a file contents instead of errors generated by HAProxy + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <code> is the HTTP status code. Currently, HAProxy is capable of + generating codes 200, 400, 401, 403, 404, 405, 407, 408, 410, + 413, 425, 429, 500, 501, 502, 503, and 504. + + <file> designates a file containing the full HTTP response. It is + recommended to follow the common practice of appending ".http" to + the filename so that people do not confuse the response with HTML + error pages, and to use absolute paths, since files are read + before any chroot is performed. + + It is important to understand that this keyword is not meant to rewrite + errors returned by the server, but errors detected and returned by HAProxy. + This is why the list of supported errors is limited to a small set. + + Code 200 is emitted in response to requests matching a "monitor-uri" rule. + + The files are parsed when HAProxy starts and must be valid according to the + HTTP specification. They should not exceed the configured buffer size + (BUFSIZE), which generally is 16 kB, otherwise an internal error will be + returned. It is also wise not to put any reference to local contents + (e.g. images) in order to avoid loops between the client and HAProxy when all + servers are down, causing an error to be returned instead of an + image. Finally, The response cannot exceed (tune.bufsize - tune.maxrewrite) + so that "http-after-response" rules still have room to operate (see + "tune.maxrewrite"). + + The files are read at the same time as the configuration and kept in memory. + For this reason, the errors continue to be returned even when the process is + chrooted, and no file change is considered while the process is running. A + simple method for developing those files consists in associating them to the + 403 status code and interrogating a blocked URL. + + See also : "http-error", "errorloc", "errorloc302", "errorloc303" + + Example : + errorfile 400 /etc/haproxy/errorfiles/400badreq.http + errorfile 408 /dev/null # work around Chrome pre-connect bug + errorfile 403 /etc/haproxy/errorfiles/403forbid.http + errorfile 503 /etc/haproxy/errorfiles/503sorry.http + + +errorfiles <name> [<code> ...] + Import, fully or partially, the error files defined in the <name> http-errors + section. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <name> is the name of an existing http-errors section. + + <code> is a HTTP status code. Several status code may be listed. + Currently, HAProxy is capable of generating codes 200, 400, 401, + 403, 404, 405, 407, 408, 410, 413, 425, 429, 500, 501, 502, 503, + and 504. + + Errors defined in the http-errors section with the name <name> are imported + in the current proxy. If no status code is specified, all error files of the + http-errors section are imported. Otherwise, only error files associated to + the listed status code are imported. Those error files override the already + defined custom errors for the proxy. And they may be overridden by following + ones. Functionally, it is exactly the same as declaring all error files by + hand using "errorfile" directives. + + See also : "http-error", "errorfile", "errorloc", "errorloc302" , + "errorloc303" and section 3.8 about http-errors. + + Example : + errorfiles generic + errorfiles site-1 403 404 + + +errorloc <code> <url> +errorloc302 <code> <url> + Return an HTTP redirection to a URL instead of errors generated by HAProxy + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <code> is the HTTP status code. Currently, HAProxy is capable of + generating codes 200, 400, 401, 403, 404, 405, 407, 408, 410, + 413, 425, 429, 500, 501, 502, 503, and 504. + + <url> it is the exact contents of the "Location" header. It may contain + either a relative URI to an error page hosted on the same site, + or an absolute URI designating an error page on another site. + Special care should be given to relative URIs to avoid redirect + loops if the URI itself may generate the same error (e.g. 500). + + It is important to understand that this keyword is not meant to rewrite + errors returned by the server, but errors detected and returned by HAProxy. + This is why the list of supported errors is limited to a small set. + + Code 200 is emitted in response to requests matching a "monitor-uri" rule. + + Note that both keyword return the HTTP 302 status code, which tells the + client to fetch the designated URL using the same HTTP method. This can be + quite problematic in case of non-GET methods such as POST, because the URL + sent to the client might not be allowed for something other than GET. To + work around this problem, please use "errorloc303" which send the HTTP 303 + status code, indicating to the client that the URL must be fetched with a GET + request. + + See also : "http-error", "errorfile", "errorloc303" + + +errorloc303 <code> <url> + Return an HTTP redirection to a URL instead of errors generated by HAProxy + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <code> is the HTTP status code. Currently, HAProxy is capable of + generating codes 200, 400, 401, 403, 404, 405, 407, 408, 410, + 413, 425, 429, 500, 501, 502, 503, and 504. + + <url> it is the exact contents of the "Location" header. It may contain + either a relative URI to an error page hosted on the same site, + or an absolute URI designating an error page on another site. + Special care should be given to relative URIs to avoid redirect + loops if the URI itself may generate the same error (e.g. 500). + + It is important to understand that this keyword is not meant to rewrite + errors returned by the server, but errors detected and returned by HAProxy. + This is why the list of supported errors is limited to a small set. + + Code 200 is emitted in response to requests matching a "monitor-uri" rule. + + Note that both keyword return the HTTP 303 status code, which tells the + client to fetch the designated URL using the same HTTP GET method. This + solves the usual problems associated with "errorloc" and the 302 code. It is + possible that some very old browsers designed before HTTP/1.1 do not support + it, but no such problem has been reported till now. + + See also : "http-error", "errorfile", "errorloc", "errorloc302" + + +email-alert from <emailaddr> + Declare the from email address to be used in both the envelope and header + of email alerts. This is the address that email alerts are sent from. + May be used in sections: defaults | frontend | listen | backend + yes | yes | yes | yes + + Arguments : + + <emailaddr> is the from email address to use when sending email alerts + + Also requires "email-alert mailers" and "email-alert to" to be set + and if so sending email alerts is enabled for the proxy. + + See also : "email-alert level", "email-alert mailers", + "email-alert myhostname", "email-alert to", section 3.6 about + mailers. + + +email-alert level <level> + Declare the maximum log level of messages for which email alerts will be + sent. This acts as a filter on the sending of email alerts. + May be used in sections: defaults | frontend | listen | backend + yes | yes | yes | yes + + Arguments : + + <level> One of the 8 syslog levels: + emerg alert crit err warning notice info debug + The above syslog levels are ordered from lowest to highest. + + By default level is alert + + Also requires "email-alert from", "email-alert mailers" and + "email-alert to" to be set and if so sending email alerts is enabled + for the proxy. + + Alerts are sent when : + + * An un-paused server is marked as down and <level> is alert or lower + * A paused server is marked as down and <level> is notice or lower + * A server is marked as up or enters the drain state and <level> + is notice or lower + * "option log-health-checks" is enabled, <level> is info or lower, + and a health check status update occurs + + See also : "email-alert from", "email-alert mailers", + "email-alert myhostname", "email-alert to", + section 3.6 about mailers. + + +email-alert mailers <mailersect> + Declare the mailers to be used when sending email alerts + May be used in sections: defaults | frontend | listen | backend + yes | yes | yes | yes + + Arguments : + + <mailersect> is the name of the mailers section to send email alerts. + + Also requires "email-alert from" and "email-alert to" to be set + and if so sending email alerts is enabled for the proxy. + + See also : "email-alert from", "email-alert level", "email-alert myhostname", + "email-alert to", section 3.6 about mailers. + + +email-alert myhostname <hostname> + Declare the to hostname address to be used when communicating with + mailers. + May be used in sections: defaults | frontend | listen | backend + yes | yes | yes | yes + + Arguments : + + <hostname> is the hostname to use when communicating with mailers + + By default the systems hostname is used. + + Also requires "email-alert from", "email-alert mailers" and + "email-alert to" to be set and if so sending email alerts is enabled + for the proxy. + + See also : "email-alert from", "email-alert level", "email-alert mailers", + "email-alert to", section 3.6 about mailers. + + +email-alert to <emailaddr> + Declare both the recipient address in the envelope and to address in the + header of email alerts. This is the address that email alerts are sent to. + May be used in sections: defaults | frontend | listen | backend + yes | yes | yes | yes + + Arguments : + + <emailaddr> is the to email address to use when sending email alerts + + Also requires "email-alert mailers" and "email-alert to" to be set + and if so sending email alerts is enabled for the proxy. + + See also : "email-alert from", "email-alert level", "email-alert mailers", + "email-alert myhostname", section 3.6 about mailers. + + +error-log-format <string> + Specifies the log format string to use in case of connection error on the frontend side. + May be used in sections: defaults | frontend | listen | backend + yes | yes | yes | no + + This directive specifies the log format string that will be used for logs + containing information related to errors, timeouts, retries redispatches or + HTTP status code 5xx. This format will in short be used for every log line + that would be concerned by the "log-separate-errors" option, including + connection errors described in section 8.2.5. + + If the directive is used in a defaults section, all subsequent frontends will + use the same log format. Please see section 8.2.4 which covers the log format + string in depth. + + "error-log-format" directive overrides previous "error-log-format" + directives. + + +force-persist { if | unless } <condition> + Declare a condition to force persistence on down servers + May be used in sections: defaults | frontend | listen | backend + no | no | yes | yes + + By default, requests are not dispatched to down servers. It is possible to + force this using "option persist", but it is unconditional and redispatches + to a valid server if "option redispatch" is set. That leaves with very little + possibilities to force some requests to reach a server which is artificially + marked down for maintenance operations. + + The "force-persist" statement allows one to declare various ACL-based + conditions which, when met, will cause a request to ignore the down status of + a server and still try to connect to it. That makes it possible to start a + server, still replying an error to the health checks, and run a specially + configured browser to test the service. Among the handy methods, one could + use a specific source IP address, or a specific cookie. The cookie also has + the advantage that it can easily be added/removed on the browser from a test + page. Once the service is validated, it is then possible to open the service + to the world by returning a valid response to health checks. + + The forced persistence is enabled when an "if" condition is met, or unless an + "unless" condition is met. The final redispatch is always disabled when this + is used. + + See also : "option redispatch", "ignore-persist", "persist", + and section 7 about ACL usage. + + +filter <name> [param*] + Add the filter <name> in the filter list attached to the proxy. + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | yes + Arguments : + <name> is the name of the filter. Officially supported filters are + referenced in section 9. + + <param*> is a list of parameters accepted by the filter <name>. The + parsing of these parameters are the responsibility of the + filter. Please refer to the documentation of the corresponding + filter (section 9) for all details on the supported parameters. + + Multiple occurrences of the filter line can be used for the same proxy. The + same filter can be referenced many times if needed. + + Example: + listen + bind *:80 + + filter trace name BEFORE-HTTP-COMP + filter compression + filter trace name AFTER-HTTP-COMP + + compression algo gzip + compression offload + + server srv1 192.168.0.1:80 + + See also : section 9. + + +fullconn <conns> + Specify at what backend load the servers will reach their maxconn + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <conns> is the number of connections on the backend which will make the + servers use the maximal number of connections. + + When a server has a "maxconn" parameter specified, it means that its number + of concurrent connections will never go higher. Additionally, if it has a + "minconn" parameter, it indicates a dynamic limit following the backend's + load. The server will then always accept at least <minconn> connections, + never more than <maxconn>, and the limit will be on the ramp between both + values when the backend has less than <conns> concurrent connections. This + makes it possible to limit the load on the servers during normal loads, but + push it further for important loads without overloading the servers during + exceptional loads. + + Since it's hard to get this value right, HAProxy automatically sets it to + 10% of the sum of the maxconns of all frontends that may branch to this + backend (based on "use_backend" and "default_backend" rules). That way it's + safe to leave it unset. However, "use_backend" involving dynamic names are + not counted since there is no way to know if they could match or not. + + Example : + # The servers will accept between 100 and 1000 concurrent connections each + # and the maximum of 1000 will be reached when the backend reaches 10000 + # connections. + backend dynamic + fullconn 10000 + server srv1 dyn1:80 minconn 100 maxconn 1000 + server srv2 dyn2:80 minconn 100 maxconn 1000 + + See also : "maxconn", "server" + + +hash-balance-factor <factor> + Specify the balancing factor for bounded-load consistent hashing + May be used in sections : defaults | frontend | listen | backend + yes | no | no | yes + Arguments : + <factor> is the control for the maximum number of concurrent requests to + send to a server, expressed as a percentage of the average number + of concurrent requests across all of the active servers. + + Specifying a "hash-balance-factor" for a server with "hash-type consistent" + enables an algorithm that prevents any one server from getting too many + requests at once, even if some hash buckets receive many more requests than + others. Setting <factor> to 0 (the default) disables the feature. Otherwise, + <factor> is a percentage greater than 100. For example, if <factor> is 150, + then no server will be allowed to have a load more than 1.5 times the average. + If server weights are used, they will be respected. + + If the first-choice server is disqualified, the algorithm will choose another + server based on the request hash, until a server with additional capacity is + found. A higher <factor> allows more imbalance between the servers, while a + lower <factor> means that more servers will be checked on average, affecting + performance. Reasonable values are from 125 to 200. + + This setting is also used by "balance random" which internally relies on the + consistent hashing mechanism. + + See also : "balance" and "hash-type". + + +hash-type <method> <function> <modifier> + Specify a method to use for mapping hashes to servers + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <method> is the method used to select a server from the hash computed by + the <function> : + + map-based the hash table is a static array containing all alive servers. + The hashes will be very smooth, will consider weights, but + will be static in that weight changes while a server is up + will be ignored. This means that there will be no slow start. + Also, since a server is selected by its position in the array, + most mappings are changed when the server count changes. This + means that when a server goes up or down, or when a server is + added to a farm, most connections will be redistributed to + different servers. This can be inconvenient with caches for + instance. + + consistent the hash table is a tree filled with many occurrences of each + server. The hash key is looked up in the tree and the closest + server is chosen. This hash is dynamic, it supports changing + weights while the servers are up, so it is compatible with the + slow start feature. It has the advantage that when a server + goes up or down, only its associations are moved. When a + server is added to the farm, only a few part of the mappings + are redistributed, making it an ideal method for caches. + However, due to its principle, the distribution will never be + very smooth and it may sometimes be necessary to adjust a + server's weight or its ID to get a more balanced distribution. + In order to get the same distribution on multiple load + balancers, it is important that all servers have the exact + same IDs. Note: consistent hash uses sdbm and avalanche if no + hash function is specified. + + <function> is the hash function to be used : + + sdbm this function was created initially for sdbm (a public-domain + reimplementation of ndbm) database library. It was found to do + well in scrambling bits, causing better distribution of the keys + and fewer splits. It also happens to be a good general hashing + function with good distribution, unless the total server weight + is a multiple of 64, in which case applying the avalanche + modifier may help. + + djb2 this function was first proposed by Dan Bernstein many years ago + on comp.lang.c. Studies have shown that for certain workload this + function provides a better distribution than sdbm. It generally + works well with text-based inputs though it can perform extremely + poorly with numeric-only input or when the total server weight is + a multiple of 33, unless the avalanche modifier is also used. + + wt6 this function was designed for HAProxy while testing other + functions in the past. It is not as smooth as the other ones, but + is much less sensible to the input data set or to the number of + servers. It can make sense as an alternative to sdbm+avalanche or + djb2+avalanche for consistent hashing or when hashing on numeric + data such as a source IP address or a visitor identifier in a URL + parameter. + + crc32 this is the most common CRC32 implementation as used in Ethernet, + gzip, PNG, etc. It is slower than the other ones but may provide + a better distribution or less predictable results especially when + used on strings. + + <modifier> indicates an optional method applied after hashing the key : + + avalanche This directive indicates that the result from the hash + function above should not be used in its raw form but that + a 4-byte full avalanche hash must be applied first. The + purpose of this step is to mix the resulting bits from the + previous hash in order to avoid any undesired effect when + the input contains some limited values or when the number of + servers is a multiple of one of the hash's components (64 + for SDBM, 33 for DJB2). Enabling avalanche tends to make the + result less predictable, but it's also not as smooth as when + using the original function. Some testing might be needed + with some workloads. This hash is one of the many proposed + by Bob Jenkins. + + The default hash type is "map-based" and is recommended for most usages. The + default function is "sdbm", the selection of a function should be based on + the range of the values being hashed. + + See also : "balance", "hash-balance-factor", "server" + + +http-after-response <action> <options...> [ { if | unless } <condition> ] + Access control for all Layer 7 responses (server, applet/service and internal + ones). + + May be used in sections: defaults | frontend | listen | backend + yes(!) | yes | yes | yes + + The http-after-response statement defines a set of rules which apply to layer + 7 processing. The rules are evaluated in their declaration order when they + are met in a frontend, listen or backend section. Any rule may optionally be + followed by an ACL-based condition, in which case it will only be evaluated + if the condition is true. Since these rules apply on responses, the backend + rules are applied first, followed by the frontend's rules. + + Unlike http-response rules, these ones are applied on all responses, the + server ones but also to all responses generated by HAProxy. These rules are + evaluated at the end of the responses analysis, before the data forwarding. + + The first keyword is the rule's action. Several types of actions are + supported: + - add-header <name> <fmt> + - allow + - capture <sample> id <id> + - del-header <name> [ -m <meth> ] + - replace-header <name> <regex-match> <replace-fmt> + - replace-value <name> <regex-match> <replace-fmt> + - set-header <name> <fmt> + - set-status <status> [reason <str>] + - set-var(<var-name>[,<cond>...]) <expr> + - set-var-fmt(<var-name>[,<cond>...]) <fmt> + - strict-mode { on | off } + - unset-var(<var-name>) + + The supported actions are described below. + + There is no limit to the number of http-after-response statements per + instance. + + This directive is only available from named defaults sections, not anonymous + ones. Rules defined in the defaults section are evaluated before ones in the + associated proxy section. To avoid ambiguities, in this case the same + defaults section cannot be used by proxies with the frontend capability and + by proxies with the backend capability. It means a listen section cannot use + a defaults section defining such rules. + + Note: Errors emitted in early stage of the request parsing are handled by the + multiplexer at a lower level, before any http analysis. Thus no + http-after-response ruleset is evaluated on these errors. + + Example: + http-after-response set-header Strict-Transport-Security "max-age=31536000" + http-after-response set-header Cache-Control "no-store,no-cache,private" + http-after-response set-header Pragma "no-cache" + +http-after-response add-header <name> <fmt> [ { if | unless } <condition> ] + + This appends an HTTP header field whose name is specified in <name> and whose + value is defined by <fmt>. Please refer to "http-request add-header" for a + complete description. + +http-after-response allow [ { if | unless } <condition> ] + + This stops the evaluation of the rules and lets the response pass the check. + No further "http-after-response" rules are evaluated for the current section. + +http-after-response capture <sample> id <id> [ { if | unless } <condition> ] + + This captures sample expression <sample> from the response buffer, and + converts it to a string. Please refer to "http-response capture" for a + complete description. + +http-after-response del-header <name> [ -m <meth> ] [ { if | unless } <condition> ] + + This removes all HTTP header fields whose name is specified in <name>. Please + refer to "http-request del-header" for a complete description. + +http-after-response replace-header <name> <regex-match> <replace-fmt> + [ { if | unless } <condition> ] + + This works like "http-response replace-header". + + Example: + http-after-response replace-header Set-Cookie (C=[^;]*);(.*) \1;ip=%bi;\2 + + # applied to: + Set-Cookie: C=1; expires=Tue, 14-Jun-2016 01:40:45 GMT + + # outputs: + Set-Cookie: C=1;ip=192.168.1.20; expires=Tue, 14-Jun-2016 01:40:45 GMT + + # assuming the backend IP is 192.168.1.20. + +http-after-response replace-value <name> <regex-match> <replace-fmt> + [ { if | unless } <condition> ] + + This works like "http-response replace-value". + + Example: + http-after-response replace-value Cache-control ^public$ private + + # applied to: + Cache-Control: max-age=3600, public + + # outputs: + Cache-Control: max-age=3600, private + +http-after-response set-header <name> <fmt> [ { if | unless } <condition> ] + + This does the same as "http-after-response add-header" except that the header + name is first removed if it existed. This is useful when passing security + information to the server, where the header must not be manipulated by + external users. + +http-after-response set-status <status> [reason <str>] + [ { if | unless } <condition> ] + + This replaces the response status code with <status> which must be an integer + between 100 and 999. Please refer to "http-response set-status" for a complete + description. + +http-after-response set-var(<var-name>[,<cond>...]) <expr> [ { if | unless } <condition> ] +http-after-response set-var-fmt(<var-name>[,<cond>...]) <fmt> [ { if | unless } <condition> ] + + This is used to set the contents of a variable. The variable is declared + inline. Please refer to "http-request set-var" and "http-request set-var-fmt" + for a complete description. + +http-after-response strict-mode { on | off } [ { if | unless } <condition> ] + + This enables or disables the strict rewriting mode for following + rules. Please refer to "http-request strict-mode" for a complete description. + +http-after-response unset-var(<var-name>) [ { if | unless } <condition> ] + + This is used to unset a variable. See "http-request set-var" for details + about <var-name>. + + +http-check comment <string> + Defines a comment for the following the http-check rule, reported in logs if + it fails. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + <string> is the comment message to add in logs if the following http-check + rule fails. + + It only works for connect, send and expect rules. It is useful to make + user-friendly error reporting. + + See also : "option httpchk", "http-check connect", "http-check send" and + "http-check expect". + + +http-check connect [default] [port <expr>] [addr <ip>] [send-proxy] + [via-socks4] [ssl] [sni <sni>] [alpn <alpn>] [linger] + [proto <name>] [comment <msg>] + Opens a new connection to perform an HTTP health check + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + comment <msg> defines a message to report if the rule evaluation fails. + + default Use default options of the server line to do the health + checks. The server options are used only if not redefined. + + port <expr> if not set, check port or server port is used. + It tells HAProxy where to open the connection to. + <port> must be a valid TCP port source integer, from 1 to + 65535 or an sample-fetch expression. + + addr <ip> defines the IP address to do the health check. + + send-proxy send a PROXY protocol string + + via-socks4 enables outgoing health checks using upstream socks4 proxy. + + ssl opens a ciphered connection + + sni <sni> specifies the SNI to use to do health checks over SSL. + + alpn <alpn> defines which protocols to advertise with ALPN. The protocol + list consists in a comma-delimited list of protocol names, + for instance: "h2,http/1.1". If it is not set, the server ALPN + is used. + + proto <name> forces the multiplexer's protocol to use for this connection. + It must be an HTTP mux protocol and it must be usable on the + backend side. The list of available protocols is reported in + haproxy -vv. + + linger cleanly close the connection instead of using a single RST. + + Just like tcp-check health checks, it is possible to configure the connection + to use to perform HTTP health check. This directive should also be used to + describe a scenario involving several request/response exchanges, possibly on + different ports or with different servers. + + When there are no TCP port configured on the server line neither server port + directive, then the first step of the http-check sequence must be to specify + the port with a "http-check connect". + + In an http-check ruleset a 'connect' is required, it is also mandatory to start + the ruleset with a 'connect' rule. Purpose is to ensure admin know what they + do. + + When a connect must start the ruleset, if may still be preceded by set-var, + unset-var or comment rules. + + Examples : + # check HTTP and HTTPs services on a server. + # first open port 80 thanks to server line port directive, then + # tcp-check opens port 443, ciphered and run a request on it: + option httpchk + + http-check connect + http-check send meth GET uri / ver HTTP/1.1 hdr host haproxy.1wt.eu + http-check expect status 200-399 + http-check connect port 443 ssl sni haproxy.1wt.eu + http-check send meth GET uri / ver HTTP/1.1 hdr host haproxy.1wt.eu + http-check expect status 200-399 + + server www 10.0.0.1 check port 80 + + See also : "option httpchk", "http-check send", "http-check expect" + + +http-check disable-on-404 + Enable a maintenance mode upon HTTP/404 response to health-checks + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + When this option is set, a server which returns an HTTP code 404 will be + excluded from further load-balancing, but will still receive persistent + connections. This provides a very convenient method for Web administrators + to perform a graceful shutdown of their servers. It is also important to note + that a server which is detected as failed while it was in this mode will not + generate an alert, just a notice. If the server responds 2xx or 3xx again, it + will immediately be reinserted into the farm. The status on the stats page + reports "NOLB" for a server in this mode. It is important to note that this + option only works in conjunction with the "httpchk" option. If this option + is used with "http-check expect", then it has precedence over it so that 404 + responses will still be considered as soft-stop. Note also that a stopped + server will stay stopped even if it replies 404s. This option is only + evaluated for running servers. + + See also : "option httpchk" and "http-check expect". + + +http-check expect [min-recv <int>] [comment <msg>] + [ok-status <st>] [error-status <st>] [tout-status <st>] + [on-success <fmt>] [on-error <fmt>] [status-code <expr>] + [!] <match> <pattern> + Make HTTP health checks consider response contents or specific status codes + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + comment <msg> defines a message to report if the rule evaluation fails. + + min-recv is optional and can define the minimum amount of data required to + evaluate the current expect rule. If the number of received bytes + is under this limit, the check will wait for more data. This + option can be used to resolve some ambiguous matching rules or to + avoid executing costly regex matches on content known to be still + incomplete. If an exact string is used, the minimum between the + string length and this parameter is used. This parameter is + ignored if it is set to -1. If the expect rule does not match, + the check will wait for more data. If set to 0, the evaluation + result is always conclusive. + + ok-status <st> is optional and can be used to set the check status if + the expect rule is successfully evaluated and if it is + the last rule in the tcp-check ruleset. "L7OK", "L7OKC", + "L6OK" and "L4OK" are supported : + - L7OK : check passed on layer 7 + - L7OKC : check conditionally passed on layer 7, set + server to NOLB state. + - L6OK : check passed on layer 6 + - L4OK : check passed on layer 4 + By default "L7OK" is used. + + error-status <st> is optional and can be used to set the check status if + an error occurred during the expect rule evaluation. + "L7OKC", "L7RSP", "L7STS", "L6RSP" and "L4CON" are + supported : + - L7OKC : check conditionally passed on layer 7, set + server to NOLB state. + - L7RSP : layer 7 invalid response - protocol error + - L7STS : layer 7 response error, for example HTTP 5xx + - L6RSP : layer 6 invalid response - protocol error + - L4CON : layer 1-4 connection problem + By default "L7RSP" is used. + + tout-status <st> is optional and can be used to set the check status if + a timeout occurred during the expect rule evaluation. + "L7TOUT", "L6TOUT", and "L4TOUT" are supported : + - L7TOUT : layer 7 (HTTP/SMTP) timeout + - L6TOUT : layer 6 (SSL) timeout + - L4TOUT : layer 1-4 timeout + By default "L7TOUT" is used. + + on-success <fmt> is optional and can be used to customize the + informational message reported in logs if the expect + rule is successfully evaluated and if it is the last rule + in the tcp-check ruleset. <fmt> is a log-format string. + + on-error <fmt> is optional and can be used to customize the + informational message reported in logs if an error + occurred during the expect rule evaluation. <fmt> is a + log-format string. + + <match> is a keyword indicating how to look for a specific pattern in the + response. The keyword may be one of "status", "rstatus", "hdr", + "fhdr", "string", or "rstring". The keyword may be preceded by an + exclamation mark ("!") to negate the match. Spaces are allowed + between the exclamation mark and the keyword. See below for more + details on the supported keywords. + + <pattern> is the pattern to look for. It may be a string, a regular + expression or a more complex pattern with several arguments. If + the string pattern contains spaces, they must be escaped with the + usual backslash ('\'). + + By default, "option httpchk" considers that response statuses 2xx and 3xx + are valid, and that others are invalid. When "http-check expect" is used, + it defines what is considered valid or invalid. Only one "http-check" + statement is supported in a backend. If a server fails to respond or times + out, the check obviously fails. The available matches are : + + status <codes> : test the status codes found parsing <codes> string. it + must be a comma-separated list of status codes or range + codes. A health check response will be considered as + valid if the response's status code matches any status + code or is inside any range of the list. If the "status" + keyword is prefixed with "!", then the response will be + considered invalid if the status code matches. + + rstatus <regex> : test a regular expression for the HTTP status code. + A health check response will be considered valid if the + response's status code matches the expression. If the + "rstatus" keyword is prefixed with "!", then the response + will be considered invalid if the status code matches. + This is mostly used to check for multiple codes. + + hdr { name | name-lf } [ -m <meth> ] <name> + [ { value | value-lf } [ -m <meth> ] <value> : + test the specified header pattern on the HTTP response + headers. The name pattern is mandatory but the value + pattern is optional. If not specified, only the header + presence is verified. <meth> is the matching method, + applied on the header name or the header value. Supported + matching methods are "str" (exact match), "beg" (prefix + match), "end" (suffix match), "sub" (substring match) or + "reg" (regex match). If not specified, exact matching + method is used. If the "name-lf" parameter is used, + <name> is evaluated as a log-format string. If "value-lf" + parameter is used, <value> is evaluated as a log-format + string. These parameters cannot be used with the regex + matching method. Finally, the header value is considered + as comma-separated list. Note that matchings are case + insensitive on the header names. + + fhdr { name | name-lf } [ -m <meth> ] <name> + [ { value | value-lf } [ -m <meth> ] <value> : + test the specified full header pattern on the HTTP + response headers. It does exactly the same than "hdr" + keyword, except the full header value is tested, commas + are not considered as delimiters. + + string <string> : test the exact string match in the HTTP response body. + A health check response will be considered valid if the + response's body contains this exact string. If the + "string" keyword is prefixed with "!", then the response + will be considered invalid if the body contains this + string. This can be used to look for a mandatory word at + the end of a dynamic page, or to detect a failure when a + specific error appears on the check page (e.g. a stack + trace). + + rstring <regex> : test a regular expression on the HTTP response body. + A health check response will be considered valid if the + response's body matches this expression. If the "rstring" + keyword is prefixed with "!", then the response will be + considered invalid if the body matches the expression. + This can be used to look for a mandatory word at the end + of a dynamic page, or to detect a failure when a specific + error appears on the check page (e.g. a stack trace). + + string-lf <fmt> : test a log-format string match in the HTTP response body. + A health check response will be considered valid if the + response's body contains the string resulting of the + evaluation of <fmt>, which follows the log-format rules. + If prefixed with "!", then the response will be + considered invalid if the body contains the string. + + It is important to note that the responses will be limited to a certain size + defined by the global "tune.bufsize" option, which defaults to 16384 bytes. + Thus, too large responses may not contain the mandatory pattern when using + "string" or "rstring". If a large response is absolutely required, it is + possible to change the default max size by setting the global variable. + However, it is worth keeping in mind that parsing very large responses can + waste some CPU cycles, especially when regular expressions are used, and that + it is always better to focus the checks on smaller resources. + + In an http-check ruleset, the last expect rule may be implicit. If no expect + rule is specified after the last "http-check send", an implicit expect rule + is defined to match on 2xx or 3xx status codes. It means this rule is also + defined if there is no "http-check" rule at all, when only "option httpchk" + is set. + + Last, if "http-check expect" is combined with "http-check disable-on-404", + then this last one has precedence when the server responds with 404. + + Examples : + # only accept status 200 as valid + http-check expect status 200,201,300-310 + + # be sure a sessid coookie is set + http-check expect header name "set-cookie" value -m beg "sessid=" + + # consider SQL errors as errors + http-check expect ! string SQL\ Error + + # consider status 5xx only as errors + http-check expect ! rstatus ^5 + + # check that we have a correct hexadecimal tag before /html + http-check expect rstring <!--tag:[0-9a-f]*--></html> + + See also : "option httpchk", "http-check connect", "http-check disable-on-404" + and "http-check send". + + +http-check send [meth <method>] [{ uri <uri> | uri-lf <fmt> }>] [ver <version>] + [hdr <name> <fmt>]* [{ body <string> | body-lf <fmt> }] + [comment <msg>] + Add a possible list of headers and/or a body to the request sent during HTTP + health checks. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + comment <msg> defines a message to report if the rule evaluation fails. + + meth <method> is the optional HTTP method used with the requests. When not + set, the "OPTIONS" method is used, as it generally requires + low server processing and is easy to filter out from the + logs. Any method may be used, though it is not recommended + to invent non-standard ones. + + uri <uri> is optional and set the URI referenced in the HTTP requests + to the string <uri>. It defaults to "/" which is accessible + by default on almost any server, but may be changed to any + other URI. Query strings are permitted. + + uri-lf <fmt> is optional and set the URI referenced in the HTTP requests + using the log-format string <fmt>. It defaults to "/" which + is accessible by default on almost any server, but may be + changed to any other URI. Query strings are permitted. + + ver <version> is the optional HTTP version string. It defaults to + "HTTP/1.0" but some servers might behave incorrectly in HTTP + 1.0, so turning it to HTTP/1.1 may sometimes help. Note that + the Host field is mandatory in HTTP/1.1, use "hdr" argument + to add it. + + hdr <name> <fmt> adds the HTTP header field whose name is specified in + <name> and whose value is defined by <fmt>, which follows + to the log-format rules. + + body <string> add the body defined by <string> to the request sent during + HTTP health checks. If defined, the "Content-Length" header + is thus automatically added to the request. + + body-lf <fmt> add the body defined by the log-format string <fmt> to the + request sent during HTTP health checks. If defined, the + "Content-Length" header is thus automatically added to the + request. + + In addition to the request line defined by the "option httpchk" directive, + this one is the valid way to add some headers and optionally a body to the + request sent during HTTP health checks. If a body is defined, the associate + "Content-Length" header is automatically added. Thus, this header or + "Transfer-encoding" header should not be present in the request provided by + "http-check send". If so, it will be ignored. The old trick consisting to add + headers after the version string on the "option httpchk" line is now + deprecated. + + Also "http-check send" doesn't support HTTP keep-alive. Keep in mind that it + will automatically append a "Connection: close" header, unless a Connection + header has already already been configured via a hdr entry. + + Note that the Host header and the request authority, when both defined, are + automatically synchronized. It means when the HTTP request is sent, when a + Host is inserted in the request, the request authority is accordingly + updated. Thus, don't be surprised if the Host header value overwrites the + configured request authority. + + Note also for now, no Host header is automatically added in HTTP/1.1 or above + requests. You should add it explicitly. + + See also : "option httpchk", "http-check send-state" and "http-check expect". + + +http-check send-state + Enable emission of a state header with HTTP health checks + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + When this option is set, HAProxy will systematically send a special header + "X-Haproxy-Server-State" with a list of parameters indicating to each server + how they are seen by HAProxy. This can be used for instance when a server is + manipulated without access to HAProxy and the operator needs to know whether + HAProxy still sees it up or not, or if the server is the last one in a farm. + + The header is composed of fields delimited by semi-colons, the first of which + is a word ("UP", "DOWN", "NOLB"), possibly followed by a number of valid + checks on the total number before transition, just as appears in the stats + interface. Next headers are in the form "<variable>=<value>", indicating in + no specific order some values available in the stats interface : + - a variable "address", containing the address of the backend server. + This corresponds to the <address> field in the server declaration. For + unix domain sockets, it will read "unix". + + - a variable "port", containing the port of the backend server. This + corresponds to the <port> field in the server declaration. For unix + domain sockets, it will read "unix". + + - a variable "name", containing the name of the backend followed by a slash + ("/") then the name of the server. This can be used when a server is + checked in multiple backends. + + - a variable "node" containing the name of the HAProxy node, as set in the + global "node" variable, otherwise the system's hostname if unspecified. + + - a variable "weight" indicating the weight of the server, a slash ("/") + and the total weight of the farm (just counting usable servers). This + helps to know if other servers are available to handle the load when this + one fails. + + - a variable "scur" indicating the current number of concurrent connections + on the server, followed by a slash ("/") then the total number of + connections on all servers of the same backend. + + - a variable "qcur" indicating the current number of requests in the + server's queue. + + Example of a header received by the application server : + >>> X-Haproxy-Server-State: UP 2/3; name=bck/srv2; node=lb1; weight=1/2; \ + scur=13/22; qcur=0 + + See also : "option httpchk", "http-check disable-on-404" and + "http-check send". + + +http-check set-var(<var-name>[,<cond>...]) <expr> +http-check set-var-fmt(<var-name>[,<cond>...]) <fmt> + This operation sets the content of a variable. The variable is declared inline. + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + <var-name> The name of the variable starts with an indication about its + scope. The scopes allowed for http-check are: + "proc" : the variable is shared with the whole process. + "sess" : the variable is shared with the tcp-check session. + "check": the variable is declared for the lifetime of the tcp-check. + This prefix is followed by a name. The separator is a '.'. + The name may only contain characters 'a-z', 'A-Z', '0-9', '.', + and '-'. + + <cond> A set of conditions that must all be true for the variable to + actually be set (such as "ifnotempty", "ifgt" ...). See the + set-var converter's description for a full list of possible + conditions. + + <expr> Is a sample-fetch expression potentially followed by converters. + + <fmt> This is the value expressed using log-format rules (see Custom + Log Format in section 8.2.4). + + Examples : + http-check set-var(check.port) int(1234) + http-check set-var-fmt(check.port) "name=%H" + + +http-check unset-var(<var-name>) + Free a reference to a variable within its scope. + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + <var-name> The name of the variable starts with an indication about its + scope. The scopes allowed for http-check are: + "proc" : the variable is shared with the whole process. + "sess" : the variable is shared with the tcp-check session. + "check": the variable is declared for the lifetime of the tcp-check. + This prefix is followed by a name. The separator is a '.'. + The name may only contain characters 'a-z', 'A-Z', '0-9', '.', + and '-'. + + Examples : + http-check unset-var(check.port) + + +http-error status <code> [content-type <type>] + [ { default-errorfiles | errorfile <file> | errorfiles <name> | + file <file> | lf-file <file> | string <str> | lf-string <fmt> } ] + [ hdr <name> <fmt> ]* + Defines a custom error message to use instead of errors generated by HAProxy. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + status <code> is the HTTP status code. It must be specified. + Currently, HAProxy is capable of generating codes + 200, 400, 401, 403, 404, 405, 407, 408, 410, 413, 425, + 429, 500, 501, 502, 503, and 504. + + content-type <type> is the response content type, for instance + "text/plain". This parameter is ignored and should be + omitted when an errorfile is configured or when the + payload is empty. Otherwise, it must be defined. + + default-errorfiles Reset the previously defined error message for current + proxy for the status <code>. If used on a backend, the + frontend error message is used, if defined. If used on + a frontend, the default error message is used. + + errorfile <file> designates a file containing the full HTTP response. + It is recommended to follow the common practice of + appending ".http" to the filename so that people do + not confuse the response with HTML error pages, and to + use absolute paths, since files are read before any + chroot is performed. + + errorfiles <name> designates the http-errors section to use to import + the error message with the status code <code>. If no + such message is found, the proxy's error messages are + considered. + + file <file> specifies the file to use as response payload. If the + file is not empty, its content-type must be set as + argument to "content-type", otherwise, any + "content-type" argument is ignored. <file> is + considered as a raw string. + + string <str> specifies the raw string to use as response payload. + The content-type must always be set as argument to + "content-type". + + lf-file <file> specifies the file to use as response payload. If the + file is not empty, its content-type must be set as + argument to "content-type", otherwise, any + "content-type" argument is ignored. <file> is + evaluated as a log-format string. + + lf-string <str> specifies the log-format string to use as response + payload. The content-type must always be set as + argument to "content-type". + + hdr <name> <fmt> adds to the response the HTTP header field whose name + is specified in <name> and whose value is defined by + <fmt>, which follows to the log-format rules. + This parameter is ignored if an errorfile is used. + + This directive may be used instead of "errorfile", to define a custom error + message. As "errorfile" directive, it is used for errors detected and + returned by HAProxy. If an errorfile is defined, it is parsed when HAProxy + starts and must be valid according to the HTTP standards. The generated + response must not exceed the configured buffer size (BUFFSIZE), otherwise an + internal error will be returned. Finally, if you consider to use some + http-after-response rules to rewrite these errors, the reserved buffer space + should be available (see "tune.maxrewrite"). + + The files are read at the same time as the configuration and kept in memory. + For this reason, the errors continue to be returned even when the process is + chrooted, and no file change is considered while the process is running. + + Note: 400/408/500 errors emitted in early stage of the request parsing are + handled by the multiplexer at a lower level. No custom formatting is + supported at this level. Thus only static error messages, defined with + "errorfile" directive, are supported. However, this limitation only + exists during the request headers parsing or between two transactions. + + See also : "errorfile", "errorfiles", "errorloc", "errorloc302", + "errorloc303" and section 3.8 about http-errors. + + +http-request <action> [options...] [ { if | unless } <condition> ] + Access control for Layer 7 requests + + May be used in sections: defaults | frontend | listen | backend + yes(!) | yes | yes | yes + + The http-request statement defines a set of rules which apply to layer 7 + processing. The rules are evaluated in their declaration order when they are + met in a frontend, listen or backend section. Any rule may optionally be + followed by an ACL-based condition, in which case it will only be evaluated + if the condition is true. + + The first keyword is the rule's action. Several types of actions are + supported: + - add-acl(<file-name>) <key fmt> + - add-header <name> <fmt> + - allow + - auth [realm <realm>] + - cache-use <name> + - capture <sample> [ len <length> | id <id> ] + - del-acl(<file-name>) <key fmt> + - del-header <name> [ -m <meth> ] + - del-map(<file-name>) <key fmt> + - deny [ { status | deny_status } <code>] ... + - disable-l7-retry + - do-resolve(<var>,<resolvers>,[ipv4,ipv6]) <expr> + - early-hint <name> <fmt> + - normalize-uri <normalizer> + - redirect <rule> + - reject + - replace-header <name> <match-regex> <replace-fmt> + - replace-path <match-regex> <replace-fmt> + - replace-pathq <match-regex> <replace-fmt> + - replace-uri <match-regex> <replace-fmt> + - replace-value <name> <match-regex> <replace-fmt> + - return [status <code>] [content-type <type>] ... + - sc-inc-gpc(<idx>,<sc-id>) + - sc-inc-gpc0(<sc-id>) + - sc-inc-gpc1(<sc-id>) + - sc-set-gpt(<idx>,<sc-id>) { <int> | <expr> } + - sc-set-gpt0(<sc-id>) { <int> | <expr> } + - set-dst <expr> + - set-dst-port <expr> + - set-header <name> <fmt> + - set-log-level <level> + - set-map(<file-name>) <key fmt> <value fmt> + - set-mark <mark> + - set-method <fmt> + - set-nice <nice> + - set-path <fmt> + - set-pathq <fmt> + - set-priority-class <expr> + - set-priority-offset <expr> + - set-query <fmt> + - set-src <expr> + - set-src-port <expr> + - set-timeout { server | tunnel } { <timeout> | <expr> } + - set-tos <tos> + - set-uri <fmt> + - set-var(<var-name>[,<cond>...]) <expr> + - set-var-fmt(<var-name>[,<cond>...]) <fmt> + - send-spoe-group <engine-name> <group-name> + - silent-drop + - strict-mode { on | off } + - tarpit [ { status | deny_status } <code>] ... + - track-sc0 <key> [table <table>] + - track-sc1 <key> [table <table>] + - track-sc2 <key> [table <table>] + - unset-var(<var-name>) + - use-service <service-name> + - wait-for-body time <time> [ at-least <bytes> ] + - wait-for-handshake + - cache-use <name> + + The supported actions are described below. + + There is no limit to the number of http-request statements per instance. + + This directive is only available from named defaults sections, not anonymous + ones. Rules defined in the defaults section are evaluated before ones in the + associated proxy section. To avoid ambiguities, in this case the same + defaults section cannot be used by proxies with the frontend capability and + by proxies with the backend capability. It means a listen section cannot use + a defaults section defining such rules. + + Example: + acl nagios src 192.168.129.3 + acl local_net src 192.168.0.0/16 + acl auth_ok http_auth(L1) + + http-request allow if nagios + http-request allow if local_net auth_ok + http-request auth realm Gimme if local_net auth_ok + http-request deny + + Example: + acl key req.hdr(X-Add-Acl-Key) -m found + acl add path /addacl + acl del path /delacl + + acl myhost hdr(Host) -f myhost.lst + + http-request add-acl(myhost.lst) %[req.hdr(X-Add-Acl-Key)] if key add + http-request del-acl(myhost.lst) %[req.hdr(X-Add-Acl-Key)] if key del + + Example: + acl value req.hdr(X-Value) -m found + acl setmap path /setmap + acl delmap path /delmap + + use_backend bk_appli if { hdr(Host),map_str(map.lst) -m found } + + http-request set-map(map.lst) %[src] %[req.hdr(X-Value)] if setmap value + http-request del-map(map.lst) %[src] if delmap + + See also : "stats http-request", section 3.4 about userlists and section 7 + about ACL usage. + +http-request add-acl(<file-name>) <key fmt> [ { if | unless } <condition> ] + + This is used to add a new entry into an ACL. The ACL must be loaded from a + file (even a dummy empty file). The file name of the ACL to be updated is + passed between parentheses. It takes one argument: <key fmt>, which follows + log-format rules, to collect content of the new entry. It performs a lookup + in the ACL before insertion, to avoid duplicated (or more) values. This + lookup is done by a linear search and can be expensive with large lists! + It is the equivalent of the "add acl" command from the stats socket, but can + be triggered by an HTTP request. + +http-request add-header <name> <fmt> [ { if | unless } <condition> ] + + This appends an HTTP header field whose name is specified in <name> and + whose value is defined by <fmt> which follows the log-format rules (see + Custom Log Format in section 8.2.4). This is particularly useful to pass + connection-specific information to the server (e.g. the client's SSL + certificate), or to combine several headers into one. This rule is not + final, so it is possible to add other similar rules. Note that header + addition is performed immediately, so one rule might reuse the resulting + header from a previous rule. + +http-request allow [ { if | unless } <condition> ] + + This stops the evaluation of the rules and lets the request pass the check. + No further "http-request" rules are evaluated for the current section. + +http-request auth [realm <realm>] [ { if | unless } <condition> ] + + This stops the evaluation of the rules and immediately responds with an + HTTP 401 or 407 error code to invite the user to present a valid user name + and password. No further "http-request" rules are evaluated. An optional + "realm" parameter is supported, it sets the authentication realm that is + returned with the response (typically the application's name). + + The corresponding proxy's error message is used. It may be customized using + an "errorfile" or an "http-error" directive. For 401 responses, all + occurrences of the WWW-Authenticate header are removed and replaced by a new + one with a basic authentication challenge for realm "<realm>". For 407 + responses, the same is done on the Proxy-Authenticate header. If the error + message must not be altered, consider to use "http-request return" rule + instead. + + Example: + acl auth_ok http_auth_group(L1) G1 + http-request auth unless auth_ok + +http-request cache-use <name> [ { if | unless } <condition> ] + + See section 6.2 about cache setup. + +http-request capture <sample> [ len <length> | id <id> ] + [ { if | unless } <condition> ] + + This captures sample expression <sample> from the request buffer, and + converts it to a string of at most <len> characters. The resulting string is + stored into the next request "capture" slot, so it will possibly appear next + to some captured HTTP headers. It will then automatically appear in the logs, + and it will be possible to extract it using sample fetch rules to feed it + into headers or anything. The length should be limited given that this size + will be allocated for each capture during the whole session life. + Please check section 7.3 (Fetching samples) and "capture request header" for + more information. + + If the keyword "id" is used instead of "len", the action tries to store the + captured string in a previously declared capture slot. This is useful to run + captures in backends. The slot id can be declared by a previous directive + "http-request capture" or with the "declare capture" keyword. + + When using this action in a backend, double check that the relevant + frontend(s) have the required capture slots otherwise, this rule will be + ignored at run time. This can't be detected at configuration parsing time + due to HAProxy's ability to dynamically resolve backend name at runtime. + +http-request del-acl(<file-name>) <key fmt> [ { if | unless } <condition> ] + + This is used to delete an entry from an ACL. The ACL must be loaded from a + file (even a dummy empty file). The file name of the ACL to be updated is + passed between parentheses. It takes one argument: <key fmt>, which follows + log-format rules, to collect content of the entry to delete. + It is the equivalent of the "del acl" command from the stats socket, but can + be triggered by an HTTP request. + +http-request del-header <name> [ -m <meth> ] [ { if | unless } <condition> ] + + This removes all HTTP header fields whose name is specified in <name>. <meth> + is the matching method, applied on the header name. Supported matching methods + are "str" (exact match), "beg" (prefix match), "end" (suffix match), "sub" + (substring match) and "reg" (regex match). If not specified, exact matching + method is used. + +http-request del-map(<file-name>) <key fmt> [ { if | unless } <condition> ] + + This is used to delete an entry from a MAP. The MAP must be loaded from a + file (even a dummy empty file). The file name of the MAP to be updated is + passed between parentheses. It takes one argument: <key fmt>, which follows + log-format rules, to collect content of the entry to delete. + It takes one argument: "file name" It is the equivalent of the "del map" + command from the stats socket, but can be triggered by an HTTP request. + +http-request deny [deny_status <status>] [ { if | unless } <condition> ] +http-request deny [ { status | deny_status } <code>] [content-type <type>] + [ { default-errorfiles | errorfile <file> | errorfiles <name> | + file <file> | lf-file <file> | string <str> | lf-string <fmt> } ] + [ hdr <name> <fmt> ]* + [ { if | unless } <condition> ] + + This stops the evaluation of the rules and immediately rejects the request. + By default an HTTP 403 error is returned. But the response may be customized + using same syntax than "http-request return" rules. Thus, see "http-request + return" for details. For compatibility purpose, when no argument is defined, + or only "deny_status", the argument "default-errorfiles" is implied. It means + "http-request deny [deny_status <status>]" is an alias of + "http-request deny [status <status>] default-errorfiles". + No further "http-request" rules are evaluated. + See also "http-request return". + +http-request disable-l7-retry [ { if | unless } <condition> ] + This disables any attempt to retry the request if it fails for any other + reason than a connection failure. This can be useful for example to make + sure POST requests aren't retried on failure. + +http-request do-resolve(<var>,<resolvers>,[ipv4,ipv6]) <expr> + [ { if | unless } <condition> ] + + This action performs a DNS resolution of the output of <expr> and stores + the result in the variable <var>. It uses the DNS resolvers section + pointed by <resolvers>. + It is possible to choose a resolution preference using the optional + arguments 'ipv4' or 'ipv6'. + When performing the DNS resolution, the client side connection is on + pause waiting till the end of the resolution. + If an IP address can be found, it is stored into <var>. If any kind of + error occurs, then <var> is not set. + One can use this action to discover a server IP address at run time and + based on information found in the request (IE a Host header). + If this action is used to find the server's IP address (using the + "set-dst" action), then the server IP address in the backend must be set + to 0.0.0.0. The do-resolve action takes an host-only parameter, any port must + be removed from the string. + + Example: + resolvers mydns + nameserver local 127.0.0.53:53 + nameserver google 8.8.8.8:53 + timeout retry 1s + hold valid 10s + hold nx 3s + hold other 3s + hold obsolete 0s + accepted_payload_size 8192 + + frontend fe + bind 10.42.0.1:80 + http-request do-resolve(txn.myip,mydns,ipv4) hdr(Host),host_only + http-request capture var(txn.myip) len 40 + + # return 503 when the variable is not set, + # which mean DNS resolution error + use_backend b_503 unless { var(txn.myip) -m found } + + default_backend be + + backend b_503 + # dummy backend used to return 503. + # one can use the errorfile directive to send a nice + # 503 error page to end users + + backend be + # rule to prevent HAProxy from reconnecting to services + # on the local network (forged DNS name used to scan the network) + http-request deny if { var(txn.myip) -m ip 127.0.0.0/8 10.0.0.0/8 } + http-request set-dst var(txn.myip) + server clear 0.0.0.0:0 + + NOTE: Don't forget to set the "protection" rules to ensure HAProxy won't + be used to scan the network or worst won't loop over itself... + +http-request early-hint <name> <fmt> [ { if | unless } <condition> ] + + This is used to build an HTTP 103 Early Hints response prior to any other one. + This appends an HTTP header field to this response whose name is specified in + <name> and whose value is defined by <fmt> which follows the log-format rules + (see Custom Log Format in section 8.2.4). This is particularly useful to pass + to the client some Link headers to preload resources required to render the + HTML documents. + + See RFC 8297 for more information. + +http-request normalize-uri <normalizer> [ { if | unless } <condition> ] +http-request normalize-uri fragment-encode [ { if | unless } <condition> ] +http-request normalize-uri fragment-strip [ { if | unless } <condition> ] +http-request normalize-uri path-merge-slashes [ { if | unless } <condition> ] +http-request normalize-uri path-strip-dot [ { if | unless } <condition> ] +http-request normalize-uri path-strip-dotdot [ full ] [ { if | unless } <condition> ] +http-request normalize-uri percent-decode-unreserved [ strict ] [ { if | unless } <condition> ] +http-request normalize-uri percent-to-uppercase [ strict ] [ { if | unless } <condition> ] +http-request normalize-uri query-sort-by-name [ { if | unless } <condition> ] + + Performs normalization of the request's URI. + + URI normalization in HAProxy 2.4 is currently available as an experimental + technical preview. As such, it requires the global directive + 'expose-experimental-directives' first to be able to invoke it. You should be + prepared that the behavior of normalizers might change to fix possible + issues, possibly breaking proper request processing in your infrastructure. + + Each normalizer handles a single type of normalization to allow for a + fine-grained selection of the level of normalization that is appropriate for + the supported backend. + + As an example the "path-strip-dotdot" normalizer might be useful for a static + fileserver that directly maps the requested URI to the path within the local + filesystem. However it might break routing of an API that expects a specific + number of segments in the path. + + It is important to note that some normalizers might result in unsafe + transformations for broken URIs. It might also be possible that a combination + of normalizers that are safe by themselves results in unsafe transformations + when improperly combined. + + As an example the "percent-decode-unreserved" normalizer might result in + unexpected results when a broken URI includes bare percent characters. One + such a broken URI is "/%%36%36" which would be decoded to "/%66" which in + turn is equivalent to "/f". By specifying the "strict" option requests to + such a broken URI would safely be rejected. + + The following normalizers are available: + + - fragment-encode: Encodes "#" as "%23". + + The "fragment-strip" normalizer should be preferred, unless it is known + that broken clients do not correctly encode '#' within the path component. + + Example: + - /#foo -> /%23foo + + - fragment-strip: Removes the URI's "fragment" component. + + According to RFC 3986#3.5 the "fragment" component of an URI should not + be sent, but handled by the User Agent after retrieving a resource. + + This normalizer should be applied first to ensure that the fragment is + not interpreted as part of the request's path component. + + Example: + - /#foo -> / + + - path-strip-dot: Removes "/./" segments within the "path" component + (RFC 3986#6.2.2.3). + + Segments including percent encoded dots ("%2E") will not be detected. Use + the "percent-decode-unreserved" normalizer first if this is undesired. + + Example: + - /. -> / + - /./bar/ -> /bar/ + - /a/./a -> /a/a + - /.well-known/ -> /.well-known/ (no change) + + - path-strip-dotdot: Normalizes "/../" segments within the "path" component + (RFC 3986#6.2.2.3). + + This merges segments that attempt to access the parent directory with + their preceding segment. + + Empty segments do not receive special treatment. Use the "merge-slashes" + normalizer first if this is undesired. + + Segments including percent encoded dots ("%2E") will not be detected. Use + the "percent-decode-unreserved" normalizer first if this is undesired. + + Example: + - /foo/../ -> / + - /foo/../bar/ -> /bar/ + - /foo/bar/../ -> /foo/ + - /../bar/ -> /../bar/ + - /bar/../../ -> /../ + - /foo//../ -> /foo/ + - /foo/%2E%2E/ -> /foo/%2E%2E/ + + If the "full" option is specified then "../" at the beginning will be + removed as well: + + Example: + - /../bar/ -> /bar/ + - /bar/../../ -> / + + - path-merge-slashes: Merges adjacent slashes within the "path" component + into a single slash. + + Example: + - // -> / + - /foo//bar -> /foo/bar + + - percent-decode-unreserved: Decodes unreserved percent encoded characters to + their representation as a regular character (RFC 3986#6.2.2.2). + + The set of unreserved characters includes all letters, all digits, "-", + ".", "_", and "~". + + Example: + - /%61dmin -> /admin + - /foo%3Fbar=baz -> /foo%3Fbar=baz (no change) + - /%%36%36 -> /%66 (unsafe) + - /%ZZ -> /%ZZ + + If the "strict" option is specified then invalid sequences will result + in a HTTP 400 Bad Request being returned. + + Example: + - /%%36%36 -> HTTP 400 + - /%ZZ -> HTTP 400 + + - percent-to-uppercase: Uppercases letters within percent-encoded sequences + (RFC 3986#6.2.2.1). + + Example: + - /%6f -> /%6F + - /%zz -> /%zz + + If the "strict" option is specified then invalid sequences will result + in a HTTP 400 Bad Request being returned. + + Example: + - /%zz -> HTTP 400 + + - query-sort-by-name: Sorts the query string parameters by parameter name. + Parameters are assumed to be delimited by '&'. Shorter names sort before + longer names and identical parameter names maintain their relative order. + + Example: + - /?c=3&a=1&b=2 -> /?a=1&b=2&c=3 + - /?aaa=3&a=1&aa=2 -> /?a=1&aa=2&aaa=3 + - /?a=3&b=4&a=1&b=5&a=2 -> /?a=3&a=1&a=2&b=4&b=5 + +http-request redirect <rule> [ { if | unless } <condition> ] + + This performs an HTTP redirection based on a redirect rule. This is exactly + the same as the "redirect" statement except that it inserts a redirect rule + which can be processed in the middle of other "http-request" rules and that + these rules use the "log-format" strings. See the "redirect" keyword for the + rule's syntax. + +http-request reject [ { if | unless } <condition> ] + + This stops the evaluation of the rules and immediately closes the connection + without sending any response. It acts similarly to the + "tcp-request content reject" rules. It can be useful to force an immediate + connection closure on HTTP/2 connections. + +http-request replace-header <name> <match-regex> <replace-fmt> + [ { if | unless } <condition> ] + + This matches the value of all occurrences of header field <name> against + <match-regex>. Matching is performed case-sensitively. Matching values are + completely replaced by <replace-fmt>. Format characters are allowed in + <replace-fmt> and work like <fmt> arguments in "http-request add-header". + Standard back-references using the backslash ('\') followed by a number are + supported. + + This action acts on whole header lines, regardless of the number of values + they may contain. Thus it is well-suited to process headers naturally + containing commas in their value, such as If-Modified-Since. Headers that + contain a comma-separated list of values, such as Accept, should be processed + using "http-request replace-value". + + Example: + http-request replace-header Cookie foo=([^;]*);(.*) foo=\1;ip=%bi;\2 + + # applied to: + Cookie: foo=foobar; expires=Tue, 14-Jun-2016 01:40:45 GMT; + + # outputs: + Cookie: foo=foobar;ip=192.168.1.20; expires=Tue, 14-Jun-2016 01:40:45 GMT; + + # assuming the backend IP is 192.168.1.20 + + http-request replace-header User-Agent curl foo + + # applied to: + User-Agent: curl/7.47.0 + + # outputs: + User-Agent: foo + +http-request replace-path <match-regex> <replace-fmt> + [ { if | unless } <condition> ] + + This works like "replace-header" except that it works on the request's path + component instead of a header. The path component starts at the first '/' + after an optional scheme+authority and ends before the question mark. Thus, + the replacement does not modify the scheme, the authority and the + query-string. + + It is worth noting that regular expressions may be more expensive to evaluate + than certain ACLs, so rare replacements may benefit from a condition to avoid + performing the evaluation at all if it does not match. + + Example: + # prefix /foo : turn /bar?q=1 into /foo/bar?q=1 : + http-request replace-path (.*) /foo\1 + + # strip /foo : turn /foo/bar?q=1 into /bar?q=1 + http-request replace-path /foo/(.*) /\1 + # or more efficient if only some requests match : + http-request replace-path /foo/(.*) /\1 if { url_beg /foo/ } + +http-request replace-pathq <match-regex> <replace-fmt> + [ { if | unless } <condition> ] + + This does the same as "http-request replace-path" except that the path + contains the query-string if any is present. Thus, the path and the + query-string are replaced. + + Example: + # suffix /foo : turn /bar?q=1 into /bar/foo?q=1 : + http-request replace-pathq ([^?]*)(\?(.*))? \1/foo\2 + +http-request replace-uri <match-regex> <replace-fmt> + [ { if | unless } <condition> ] + + This works like "replace-header" except that it works on the request's URI part + instead of a header. The URI part may contain an optional scheme, authority or + query string. These are considered to be part of the value that is matched + against. + + It is worth noting that regular expressions may be more expensive to evaluate + than certain ACLs, so rare replacements may benefit from a condition to avoid + performing the evaluation at all if it does not match. + + IMPORTANT NOTE: historically in HTTP/1.x, the vast majority of requests sent + by browsers use the "origin form", which differs from the "absolute form" in + that they do not contain a scheme nor authority in the URI portion. Mostly + only requests sent to proxies, those forged by hand and some emitted by + certain applications use the absolute form. As such, "replace-uri" usually + works fine most of the time in HTTP/1.x with rules starting with a "/". But + with HTTP/2, clients are encouraged to send absolute URIs only, which look + like the ones HTTP/1 clients use to talk to proxies. Such partial replace-uri + rules may then fail in HTTP/2 when they work in HTTP/1. Either the rules need + to be adapted to optionally match a scheme and authority, or replace-path + should be used. + + Example: + # rewrite all "http" absolute requests to "https": + http-request replace-uri ^http://(.*) https://\1 + + # prefix /foo : turn /bar?q=1 into /foo/bar?q=1 : + http-request replace-uri ([^/:]*://[^/]*)?(.*) \1/foo\2 + +http-request replace-value <name> <match-regex> <replace-fmt> + [ { if | unless } <condition> ] + + This works like "replace-header" except that it matches the regex against + every comma-delimited value of the header field <name> instead of the + entire header. This is suited for all headers which are allowed to carry + more than one value. An example could be the Accept header. + + Example: + http-request replace-value X-Forwarded-For ^192\.168\.(.*)$ 172.16.\1 + + # applied to: + X-Forwarded-For: 192.168.10.1, 192.168.13.24, 10.0.0.37 + + # outputs: + X-Forwarded-For: 172.16.10.1, 172.16.13.24, 10.0.0.37 + +http-request return [status <code>] [content-type <type>] + [ { default-errorfiles | errorfile <file> | errorfiles <name> | + file <file> | lf-file <file> | string <str> | lf-string <fmt> } ] + [ hdr <name> <fmt> ]* + [ { if | unless } <condition> ] + + This stops the evaluation of the rules and immediately returns a response. The + default status code used for the response is 200. It can be optionally + specified as an arguments to "status". The response content-type may also be + specified as an argument to "content-type". Finally the response itself may + be defined. It can be a full HTTP response specifying the errorfile to use, + or the response payload specifying the file or the string to use. These rules + are followed to create the response : + + * If neither the errorfile nor the payload to use is defined, a dummy + response is returned. Only the "status" argument is considered. It can be + any code in the range [200, 599]. The "content-type" argument, if any, is + ignored. + + * If "default-errorfiles" argument is set, the proxy's errorfiles are + considered. If the "status" argument is defined, it must be one of the + status code handled by HAProxy (200, 400, 403, 404, 405, 408, 410, 413, + 425, 429, 500, 501, 502, 503, and 504). The "content-type" argument, if + any, is ignored. + + * If a specific errorfile is defined, with an "errorfile" argument, the + corresponding file, containing a full HTTP response, is returned. Only the + "status" argument is considered. It must be one of the status code handled + by HAProxy (200, 400, 403, 404, 405, 408, 410, 413, 425, 429, 500, 501, + 502, 503, and 504). The "content-type" argument, if any, is ignored. + + * If an http-errors section is defined, with an "errorfiles" argument, the + corresponding file in the specified http-errors section, containing a full + HTTP response, is returned. Only the "status" argument is considered. It + must be one of the status code handled by HAProxy (200, 400, 403, 404, 405, + 408, 410, 413, 425, 429, 500, 501, 502, 503, and 504). The "content-type" + argument, if any, is ignored. + + * If a "file" or a "lf-file" argument is specified, the file's content is + used as the response payload. If the file is not empty, its content-type + must be set as argument to "content-type". Otherwise, any "content-type" + argument is ignored. With a "lf-file" argument, the file's content is + evaluated as a log-format string. With a "file" argument, it is considered + as a raw content. + + * If a "string" or "lf-string" argument is specified, the defined string is + used as the response payload. The content-type must always be set as + argument to "content-type". With a "lf-string" argument, the string is + evaluated as a log-format string. With a "string" argument, it is + considered as a raw string. + + When the response is not based on an errorfile, it is possible to append HTTP + header fields to the response using "hdr" arguments. Otherwise, all "hdr" + arguments are ignored. For each one, the header name is specified in <name> + and its value is defined by <fmt> which follows the log-format rules. + + Note that the generated response must be smaller than a buffer. And to avoid + any warning, when an errorfile or a raw file is loaded, the buffer space + reserved for the headers rewriting should also be free. + + No further "http-request" rules are evaluated. + + Example: + http-request return errorfile /etc/haproxy/errorfiles/200.http \ + if { path /ping } + + http-request return content-type image/x-icon file /var/www/favicon.ico \ + if { path /favicon.ico } + + http-request return status 403 content-type text/plain \ + lf-string "Access denied. IP %[src] is blacklisted." \ + if { src -f /etc/haproxy/blacklist.lst } + +http-request sc-inc-gpc(<idx>,<sc-id>) [ { if | unless } <condition> ] + + This actions increments the General Purpose Counter at the index <idx> + of the array associated to the sticky counter designated by <sc-id>. + If an error occurs, this action silently fails and the actions evaluation + continues. <idx> is an integer between 0 and 99 and <sc-id> is an integer + between 0 and 2. It also silently fails if the there is no GPC stored + at this index. + This action applies only to the 'gpc' and 'gpc_rate' array data_types (and + not to the legacy 'gpc0', 'gpc1', 'gpc0_rate' nor 'gpc1_rate' data_types). + +http-request sc-inc-gpc0(<sc-id>) [ { if | unless } <condition> ] +http-request sc-inc-gpc1(<sc-id>) [ { if | unless } <condition> ] + + This actions increments the GPC0 or GPC1 counter according with the sticky + counter designated by <sc-id>. If an error occurs, this action silently fails + and the actions evaluation continues. + +http-request sc-set-gpt(<idx>,<sc-id>) { <int> | <expr> } + [ { if | unless } <condition> ] + This action sets the 32-bit unsigned GPT at the index <idx> of the array + associated to the sticky counter designated by <sc-id> at the value of + <int>/<expr>. The expected result is a boolean. + If an error occurs, this action silently fails and the actions evaluation + continues. <idx> is an integer between 0 and 99 and <sc-id> is an integer + between 0 and 2. It also silently fails if the there is no GPT stored + at this index. + This action applies only to the 'gpt' array data_type (and not to the + legacy 'gpt0' data-type). + +http-request sc-set-gpt0(<sc-id>) { <int> | <expr> } + [ { if | unless } <condition> ] + + This action sets the 32-bit unsigned GPT0 tag according to the sticky counter + designated by <sc-id> and the value of <int>/<expr>. The expected result is a + boolean. If an error occurs, this action silently fails and the actions + evaluation continues. + +http-request send-spoe-group <engine-name> <group-name> + [ { if | unless } <condition> ] + + This action is used to trigger sending of a group of SPOE messages. To do so, + the SPOE engine used to send messages must be defined, as well as the SPOE + group to send. Of course, the SPOE engine must refer to an existing SPOE + filter. If not engine name is provided on the SPOE filter line, the SPOE + agent name must be used. + + Arguments: + <engine-name> The SPOE engine name. + + <group-name> The SPOE group name as specified in the engine + configuration. + +http-request set-dst <expr> [ { if | unless } <condition> ] + + This is used to set the destination IP address to the value of specified + expression. Useful when a proxy in front of HAProxy rewrites destination IP, + but provides the correct IP in a HTTP header; or you want to mask the IP for + privacy. If you want to connect to the new address/port, use '0.0.0.0:0' as a + server address in the backend. + + Arguments: + <expr> Is a standard HAProxy expression formed by a sample-fetch followed + by some converters. + + Example: + http-request set-dst hdr(x-dst) + http-request set-dst dst,ipmask(24) + + When possible, set-dst preserves the original destination port as long as the + address family allows it, otherwise the destination port is set to 0. + +http-request set-dst-port <expr> [ { if | unless } <condition> ] + + This is used to set the destination port address to the value of specified + expression. If you want to connect to the new address/port, use '0.0.0.0:0' + as a server address in the backend. + + Arguments: + <expr> Is a standard HAProxy expression formed by a sample-fetch + followed by some converters. + + Example: + http-request set-dst-port hdr(x-port) + http-request set-dst-port int(4000) + + When possible, set-dst-port preserves the original destination address as + long as the address family supports a port, otherwise it forces the + destination address to IPv4 "0.0.0.0" before rewriting the port. + +http-request set-header <name> <fmt> [ { if | unless } <condition> ] + + This does the same as "http-request add-header" except that the header name + is first removed if it existed. This is useful when passing security + information to the server, where the header must not be manipulated by + external users. Note that the new value is computed before the removal so it + is possible to concatenate a value to an existing header. + + Example: + http-request set-header X-Haproxy-Current-Date %T + http-request set-header X-SSL %[ssl_fc] + http-request set-header X-SSL-Session_ID %[ssl_fc_session_id,hex] + http-request set-header X-SSL-Client-Verify %[ssl_c_verify] + http-request set-header X-SSL-Client-DN %{+Q}[ssl_c_s_dn] + http-request set-header X-SSL-Client-CN %{+Q}[ssl_c_s_dn(cn)] + http-request set-header X-SSL-Issuer %{+Q}[ssl_c_i_dn] + http-request set-header X-SSL-Client-NotBefore %{+Q}[ssl_c_notbefore] + http-request set-header X-SSL-Client-NotAfter %{+Q}[ssl_c_notafter] + +http-request set-log-level <level> [ { if | unless } <condition> ] + + This is used to change the log level of the current request when a certain + condition is met. Valid levels are the 8 syslog levels (see the "log" + keyword) plus the special level "silent" which disables logging for this + request. This rule is not final so the last matching rule wins. This rule + can be useful to disable health checks coming from another equipment. + +http-request set-map(<file-name>) <key fmt> <value fmt> + [ { if | unless } <condition> ] + + This is used to add a new entry into a MAP. The MAP must be loaded from a + file (even a dummy empty file). The file name of the MAP to be updated is + passed between parentheses. It takes 2 arguments: <key fmt>, which follows + log-format rules, used to collect MAP key, and <value fmt>, which follows + log-format rules, used to collect content for the new entry. + It performs a lookup in the MAP before insertion, to avoid duplicated (or + more) values. This lookup is done by a linear search and can be expensive + with large lists! It is the equivalent of the "set map" command from the + stats socket, but can be triggered by an HTTP request. + +http-request set-mark <mark> [ { if | unless } <condition> ] + + This is used to set the Netfilter/IPFW MARK on all packets sent to the client + to the value passed in <mark> on platforms which support it. This value is an + unsigned 32 bit value which can be matched by netfilter/ipfw and by the + routing table or monitoring the packets through DTrace. It can be expressed + both in decimal or hexadecimal format (prefixed by "0x"). + This can be useful to force certain packets to take a different route (for + example a cheaper network path for bulk downloads). This works on Linux + kernels 2.6.32 and above and requires admin privileges, as well on FreeBSD + and OpenBSD. + +http-request set-method <fmt> [ { if | unless } <condition> ] + + This rewrites the request method with the result of the evaluation of format + string <fmt>. There should be very few valid reasons for having to do so as + this is more likely to break something than to fix it. + +http-request set-nice <nice> [ { if | unless } <condition> ] + + This sets the "nice" factor of the current request being processed. It only + has effect against the other requests being processed at the same time. + The default value is 0, unless altered by the "nice" setting on the "bind" + line. The accepted range is -1024..1024. The higher the value, the nicest + the request will be. Lower values will make the request more important than + other ones. This can be useful to improve the speed of some requests, or + lower the priority of non-important requests. Using this setting without + prior experimentation can cause some major slowdown. + +http-request set-path <fmt> [ { if | unless } <condition> ] + + This rewrites the request path with the result of the evaluation of format + string <fmt>. The query string, if any, is left intact. If a scheme and + authority is found before the path, they are left intact as well. If the + request doesn't have a path ("*"), this one is replaced with the format. + This can be used to prepend a directory component in front of a path for + example. See also "http-request set-query" and "http-request set-uri". + + Example : + # prepend the host name before the path + http-request set-path /%[hdr(host)]%[path] + +http-request set-pathq <fmt> [ { if | unless } <condition> ] + + This does the same as "http-request set-path" except that the query-string is + also rewritten. It may be used to remove the query-string, including the + question mark (it is not possible using "http-request set-query"). + +http-request set-priority-class <expr> [ { if | unless } <condition> ] + + This is used to set the queue priority class of the current request. + The value must be a sample expression which converts to an integer in the + range -2047..2047. Results outside this range will be truncated. + The priority class determines the order in which queued requests are + processed. Lower values have higher priority. + +http-request set-priority-offset <expr> [ { if | unless } <condition> ] + + This is used to set the queue priority timestamp offset of the current + request. The value must be a sample expression which converts to an integer + in the range -524287..524287. Results outside this range will be truncated. + When a request is queued, it is ordered first by the priority class, then by + the current timestamp adjusted by the given offset in milliseconds. Lower + values have higher priority. + Note that the resulting timestamp is is only tracked with enough precision + for 524,287ms (8m44s287ms). If the request is queued long enough to where the + adjusted timestamp exceeds this value, it will be misidentified as highest + priority. Thus it is important to set "timeout queue" to a value, where when + combined with the offset, does not exceed this limit. + +http-request set-query <fmt> [ { if | unless } <condition> ] + + This rewrites the request's query string which appears after the first + question mark ("?") with the result of the evaluation of format string <fmt>. + The part prior to the question mark is left intact. If the request doesn't + contain a question mark and the new value is not empty, then one is added at + the end of the URI, followed by the new value. If a question mark was + present, it will never be removed even if the value is empty. This can be + used to add or remove parameters from the query string. + + See also "http-request set-query" and "http-request set-uri". + + Example: + # replace "%3D" with "=" in the query string + http-request set-query %[query,regsub(%3D,=,g)] + +http-request set-src <expr> [ { if | unless } <condition> ] + This is used to set the source IP address to the value of specified + expression. Useful when a proxy in front of HAProxy rewrites source IP, but + provides the correct IP in a HTTP header; or you want to mask source IP for + privacy. All subsequent calls to "src" fetch will return this value + (see example). + + Arguments : + <expr> Is a standard HAProxy expression formed by a sample-fetch followed + by some converters. + + See also "option forwardfor". + + Example: + http-request set-src hdr(x-forwarded-for) + http-request set-src src,ipmask(24) + + # After the masking this will track connections + # based on the IP address with the last byte zeroed out. + http-request track-sc0 src + + When possible, set-src preserves the original source port as long as the + address family allows it, otherwise the source port is set to 0. + +http-request set-src-port <expr> [ { if | unless } <condition> ] + + This is used to set the source port address to the value of specified + expression. + + Arguments: + <expr> Is a standard HAProxy expression formed by a sample-fetch followed + by some converters. + + Example: + http-request set-src-port hdr(x-port) + http-request set-src-port int(4000) + + When possible, set-src-port preserves the original source address as long as + the address family supports a port, otherwise it forces the source address to + IPv4 "0.0.0.0" before rewriting the port. + +http-request set-timeout { server | tunnel } { <timeout> | <expr> } + [ { if | unless } <condition> ] + + This action overrides the specified "server" or "tunnel" timeout for the + current stream only. The timeout can be specified in millisecond or with any + other unit if the number is suffixed by the unit as explained at the top of + this document. It is also possible to write an expression which must returns + a number interpreted as a timeout in millisecond. + + Note that the server/tunnel timeouts are only relevant on the backend side + and thus this rule is only available for the proxies with backend + capabilities. Also the timeout value must be non-null to obtain the expected + results. + + Example: + http-request set-timeout tunnel 5s + http-request set-timeout server req.hdr(host),map_int(host.lst) + +http-request set-tos <tos> [ { if | unless } <condition> ] + + This is used to set the TOS or DSCP field value of packets sent to the client + to the value passed in <tos> on platforms which support this. This value + represents the whole 8 bits of the IP TOS field, and can be expressed both in + decimal or hexadecimal format (prefixed by "0x"). Note that only the 6 higher + bits are used in DSCP or TOS, and the two lower bits are always 0. This can + be used to adjust some routing behavior on border routers based on some + information from the request. + + See RFC 2474, 2597, 3260 and 4594 for more information. + +http-request set-uri <fmt> [ { if | unless } <condition> ] + + This rewrites the request URI with the result of the evaluation of format + string <fmt>. The scheme, authority, path and query string are all replaced + at once. This can be used to rewrite hosts in front of proxies, or to perform + complex modifications to the URI such as moving parts between the path and + the query string. If an absolute URI is set, it will be sent as is to + HTTP/1.1 servers. If it is not the desired behavior, the host, the path + and/or the query string should be set separately. + See also "http-request set-path" and "http-request set-query". + +http-request set-var(<var-name>[,<cond>...]) <expr> [ { if | unless } <condition> ] +http-request set-var-fmt(<var-name>[,<cond>...]) <fmt> [ { if | unless } <condition> ] + + This is used to set the contents of a variable. The variable is declared + inline. + + Arguments: + <var-name> The name of the variable starts with an indication about its + scope. The scopes allowed are: + "proc" : the variable is shared with the whole process + "sess" : the variable is shared with the whole session + "txn" : the variable is shared with the transaction + (request and response) + "req" : the variable is shared only during request + processing + "res" : the variable is shared only during response + processing + This prefix is followed by a name. The separator is a '.'. + The name may only contain characters 'a-z', 'A-Z', '0-9' + and '_'. + + <cond> A set of conditions that must all be true for the variable to + actually be set (such as "ifnotempty", "ifgt" ...). See the + set-var converter's description for a full list of possible + conditions. + + <expr> Is a standard HAProxy expression formed by a sample-fetch + followed by some converters. + + <fmt> This is the value expressed using log-format rules (see Custom + Log Format in section 8.2.4). + + Example: + http-request set-var(req.my_var) req.fhdr(user-agent),lower + http-request set-var-fmt(txn.from) %[src]:%[src_port] + +http-request silent-drop [ { if | unless } <condition> ] + + This stops the evaluation of the rules and makes the client-facing connection + suddenly disappear using a system-dependent way that tries to prevent the + client from being notified. The effect it then that the client still sees an + established connection while there's none on HAProxy. The purpose is to + achieve a comparable effect to "tarpit" except that it doesn't use any local + resource at all on the machine running HAProxy. It can resist much higher + loads than "tarpit", and slow down stronger attackers. It is important to + understand the impact of using this mechanism. All stateful equipment placed + between the client and HAProxy (firewalls, proxies, load balancers) will also + keep the established connection for a long time and may suffer from this + action. + On modern Linux systems running with enough privileges, the TCP_REPAIR socket + option is used to block the emission of a TCP reset. On other systems, the + socket's TTL is reduced to 1 so that the TCP reset doesn't pass the first + router, though it's still delivered to local networks. Do not use it unless + you fully understand how it works. + +http-request strict-mode { on | off } [ { if | unless } <condition> ] + + This enables or disables the strict rewriting mode for following rules. It + does not affect rules declared before it and it is only applicable on rules + performing a rewrite on the requests. When the strict mode is enabled, any + rewrite failure triggers an internal error. Otherwise, such errors are + silently ignored. The purpose of the strict rewriting mode is to make some + rewrites optional while others must be performed to continue the request + processing. + + By default, the strict rewriting mode is enabled. Its value is also reset + when a ruleset evaluation ends. So, for instance, if you change the mode on + the frontend, the default mode is restored when HAProxy starts the backend + rules evaluation. + +http-request tarpit [deny_status <status>] [ { if | unless } <condition> ] +http-request tarpit [ { status | deny_status } <code>] [content-type <type>] + [ { default-errorfiles | errorfile <file> | errorfiles <name> | + file <file> | lf-file <file> | string <str> | lf-string <fmt> } ] + [ hdr <name> <fmt> ]* + [ { if | unless } <condition> ] + + This stops the evaluation of the rules and immediately blocks the request + without responding for a delay specified by "timeout tarpit" or + "timeout connect" if the former is not set. After that delay, if the client + is still connected, a response is returned so that the client does not + suspect it has been tarpitted. Logs will report the flags "PT". The goal of + the tarpit rule is to slow down robots during an attack when they're limited + on the number of concurrent requests. It can be very efficient against very + dumb robots, and will significantly reduce the load on firewalls compared to + a "deny" rule. But when facing "correctly" developed robots, it can make + things worse by forcing HAProxy and the front firewall to support insane + number of concurrent connections. By default an HTTP error 500 is returned. + But the response may be customized using same syntax than + "http-request return" rules. Thus, see "http-request return" for details. + For compatibility purpose, when no argument is defined, or only "deny_status", + the argument "default-errorfiles" is implied. It means + "http-request tarpit [deny_status <status>]" is an alias of + "http-request tarpit [status <status>] default-errorfiles". + No further "http-request" rules are evaluated. + See also "http-request return" and "http-request silent-drop". + +http-request track-sc0 <key> [table <table>] [ { if | unless } <condition> ] +http-request track-sc1 <key> [table <table>] [ { if | unless } <condition> ] +http-request track-sc2 <key> [table <table>] [ { if | unless } <condition> ] + + This enables tracking of sticky counters from current request. These rules do + not stop evaluation and do not change default action. The number of counters + that may be simultaneously tracked by the same connection is set in + MAX_SESS_STKCTR at build time (reported in haproxy -vv) which defaults to 3, + so the track-sc number is between 0 and (MAX_SESS_STKCTR-1). The first + "track-sc0" rule executed enables tracking of the counters of the specified + table as the first set. The first "track-sc1" rule executed enables tracking + of the counters of the specified table as the second set. The first + "track-sc2" rule executed enables tracking of the counters of the specified + table as the third set. It is a recommended practice to use the first set of + counters for the per-frontend counters and the second set for the per-backend + ones. But this is just a guideline, all may be used everywhere. + + Arguments : + <key> is mandatory, and is a sample expression rule as described in + section 7.3. It describes what elements of the incoming request or + connection will be analyzed, extracted, combined, and used to + select which table entry to update the counters. + + <table> is an optional table to be used instead of the default one, which + is the stick-table declared in the current proxy. All the counters + for the matches and updates for the key will then be performed in + that table until the session ends. + + Once a "track-sc*" rule is executed, the key is looked up in the table and if + it is not found, an entry is allocated for it. Then a pointer to that entry + is kept during all the session's life, and this entry's counters are updated + as often as possible, every time the session's counters are updated, and also + systematically when the session ends. Counters are only updated for events + that happen after the tracking has been started. As an exception, connection + counters and request counters are systematically updated so that they reflect + useful information. + + If the entry tracks concurrent connection counters, one connection is counted + for as long as the entry is tracked, and the entry will not expire during + that time. Tracking counters also provides a performance advantage over just + checking the keys, because only one table lookup is performed for all ACL + checks that make use of it. + +http-request unset-var(<var-name>) [ { if | unless } <condition> ] + + This is used to unset a variable. See above for details about <var-name>. + + Example: + http-request unset-var(req.my_var) + +http-request use-service <service-name> [ { if | unless } <condition> ] + + This directive executes the configured HTTP service to reply to the request + and stops the evaluation of the rules. An HTTP service may choose to reply by + sending any valid HTTP response or it may immediately close the connection + without sending any response. Outside natives services, for instance the + Prometheus exporter, it is possible to write your own services in Lua. No + further "http-request" rules are evaluated. + + Arguments : + <service-name> is mandatory. It is the service to call + + Example: + http-request use-service prometheus-exporter if { path /metrics } + +http-request wait-for-body time <time> [ at-least <bytes> ] + [ { if | unless } <condition> ] + + This will delay the processing of the request waiting for the payload for at + most <time> milliseconds. if "at-least" argument is specified, HAProxy stops + to wait the payload when the first <bytes> bytes are received. 0 means no + limit, it is the default value. Regardless the "at-least" argument value, + HAProxy stops to wait if the whole payload is received or if the request + buffer is full. This action may be used as a replacement to "option + http-buffer-request". + + Arguments : + + <time> is mandatory. It is the maximum time to wait for the body. It + follows the HAProxy time format and is expressed in milliseconds. + + <bytes> is optional. It is the minimum payload size to receive to stop to + wait. It follows the HAProxy size format and is expressed in + bytes. + + Example: + http-request wait-for-body time 1s at-least 1k if METH_POST + + See also : "option http-buffer-request" + +http-request wait-for-handshake [ { if | unless } <condition> ] + + This will delay the processing of the request until the SSL handshake + happened. This is mostly useful to delay processing early data until we're + sure they are valid. + + +http-response <action> <options...> [ { if | unless } <condition> ] + Access control for Layer 7 responses + + May be used in sections: defaults | frontend | listen | backend + yes(!) | yes | yes | yes + + The http-response statement defines a set of rules which apply to layer 7 + processing. The rules are evaluated in their declaration order when they are + met in a frontend, listen or backend section. Any rule may optionally be + followed by an ACL-based condition, in which case it will only be evaluated + if the condition is true. Since these rules apply on responses, the backend + rules are applied first, followed by the frontend's rules. + + The first keyword is the rule's action. Several types of actions are + supported: + - add-acl(<file-name>) <key fmt> + - add-header <name> <fmt> + - allow + - cache-store <name> + - capture <sample> id <id> + - del-acl(<file-name>) <key fmt> + - del-header <name> [ -m <meth> ] + - del-map(<file-name>) <key fmt> + - deny [ { status | deny_status } <code>] ... + - redirect <rule> + - replace-header <name> <regex-match> <replace-fmt> + - replace-value <name> <regex-match> <replace-fmt> + - return [status <code>] [content-type <type>] ... + - sc-inc-gpc(<idx>,<sc-id>) + - sc-inc-gpc0(<sc-id>) + - sc-inc-gpc1(<sc-id>) + - sc-set-gpt(<idx>,<sc-id>) { <int> | <expr> } + - sc-set-gpt0(<sc-id>) { <int> | <expr> } + - send-spoe-group <engine-name> <group-name> + - set-header <name> <fmt> + - set-log-level <level> + - set-map(<file-name>) <key fmt> <value fmt> + - set-mark <mark> + - set-nice <nice> + - set-status <status> [reason <str>] + - set-tos <tos> + - set-var(<var-name>[,<cond>...]) <expr> + - set-var-fmt(<var-name>[,<cond>...]) <fmt> + - silent-drop + - strict-mode { on | off } + - track-sc0 <key> [table <table>] + - track-sc1 <key> [table <table>] + - track-sc2 <key> [table <table>] + - unset-var(<var-name>) + - wait-for-body time <time> [ at-least <bytes> ] + + The supported actions are described below. + + There is no limit to the number of http-response statements per instance. + + This directive is only available from named defaults sections, not anonymous + ones. Rules defined in the defaults section are evaluated before ones in the + associated proxy section. To avoid ambiguities, in this case the same + defaults section cannot be used by proxies with the frontend capability and + by proxies with the backend capability. It means a listen section cannot use + a defaults section defining such rules. + + Example: + acl key_acl res.hdr(X-Acl-Key) -m found + + acl myhost hdr(Host) -f myhost.lst + + http-response add-acl(myhost.lst) %[res.hdr(X-Acl-Key)] if key_acl + http-response del-acl(myhost.lst) %[res.hdr(X-Acl-Key)] if key_acl + + Example: + acl value res.hdr(X-Value) -m found + + use_backend bk_appli if { hdr(Host),map_str(map.lst) -m found } + + http-response set-map(map.lst) %[src] %[res.hdr(X-Value)] if value + http-response del-map(map.lst) %[src] if ! value + + See also : "http-request", section 3.4 about userlists and section 7 about + ACL usage. + +http-response add-acl(<file-name>) <key fmt> [ { if | unless } <condition> ] + + This is used to add a new entry into an ACL. Please refer to "http-request + add-acl" for a complete description. + +http-response add-header <name> <fmt> [ { if | unless } <condition> ] + + This appends an HTTP header field whose name is specified in <name> and whose + value is defined by <fmt>. Please refer to "http-request add-header" for a + complete description. + +http-response allow [ { if | unless } <condition> ] + + This stops the evaluation of the rules and lets the response pass the check. + No further "http-response" rules are evaluated for the current section. + +http-response cache-store <name> [ { if | unless } <condition> ] + + See section 6.2 about cache setup. + +http-response capture <sample> id <id> [ { if | unless } <condition> ] + + This captures sample expression <sample> from the response buffer, and + converts it to a string. The resulting string is stored into the next request + "capture" slot, so it will possibly appear next to some captured HTTP + headers. It will then automatically appear in the logs, and it will be + possible to extract it using sample fetch rules to feed it into headers or + anything. Please check section 7.3 (Fetching samples) and + "capture response header" for more information. + + The keyword "id" is the id of the capture slot which is used for storing the + string. The capture slot must be defined in an associated frontend. + This is useful to run captures in backends. The slot id can be declared by a + previous directive "http-response capture" or with the "declare capture" + keyword. + + When using this action in a backend, double check that the relevant + frontend(s) have the required capture slots otherwise, this rule will be + ignored at run time. This can't be detected at configuration parsing time + due to HAProxy's ability to dynamically resolve backend name at runtime. + +http-response del-acl(<file-name>) <key fmt> [ { if | unless } <condition> ] + + This is used to delete an entry from an ACL. Please refer to "http-request + del-acl" for a complete description. + +http-response del-header <name> [ -m <meth> ] [ { if | unless } <condition> ] + + This removes all HTTP header fields whose name is specified in <name>. Please + refer to "http-request del-header" for a complete description. + +http-response del-map(<file-name>) <key fmt> [ { if | unless } <condition> ] + + This is used to delete an entry from a MAP. Please refer to "http-request + del-map" for a complete description. + +http-response deny [deny_status <status>] [ { if | unless } <condition> ] +http-response deny [ { status | deny_status } <code>] [content-type <type>] + [ { default-errorfiles | errorfile <file> | errorfiles <name> | + file <file> | lf-file <file> | string <str> | lf-string <fmt> } ] + [ hdr <name> <fmt> ]* + [ { if | unless } <condition> ] + + This stops the evaluation of the rules and immediately rejects the response. + By default an HTTP 502 error is returned. But the response may be customized + using same syntax than "http-response return" rules. Thus, see + "http-response return" for details. For compatibility purpose, when no + argument is defined, or only "deny_status", the argument "default-errorfiles" + is implied. It means "http-response deny [deny_status <status>]" is an alias + of "http-response deny [status <status>] default-errorfiles". + No further "http-response" rules are evaluated. + See also "http-response return". + +http-response redirect <rule> [ { if | unless } <condition> ] + + This performs an HTTP redirection based on a redirect rule. + This supports a format string similarly to "http-request redirect" rules, + with the exception that only the "location" type of redirect is possible on + the response. See the "redirect" keyword for the rule's syntax. When a + redirect rule is applied during a response, connections to the server are + closed so that no data can be forwarded from the server to the client. + +http-response replace-header <name> <regex-match> <replace-fmt> + [ { if | unless } <condition> ] + + This works like "http-request replace-header" except that it works on the + server's response instead of the client's request. + + Example: + http-response replace-header Set-Cookie (C=[^;]*);(.*) \1;ip=%bi;\2 + + # applied to: + Set-Cookie: C=1; expires=Tue, 14-Jun-2016 01:40:45 GMT + + # outputs: + Set-Cookie: C=1;ip=192.168.1.20; expires=Tue, 14-Jun-2016 01:40:45 GMT + + # assuming the backend IP is 192.168.1.20. + +http-response replace-value <name> <regex-match> <replace-fmt> + [ { if | unless } <condition> ] + + This works like "http-request replace-value" except that it works on the + server's response instead of the client's request. + + Example: + http-response replace-value Cache-control ^public$ private + + # applied to: + Cache-Control: max-age=3600, public + + # outputs: + Cache-Control: max-age=3600, private + +http-response return [status <code>] [content-type <type>] + [ { default-errorfiles | errorfile <file> | errorfiles <name> | + file <file> | lf-file <file> | string <str> | lf-string <fmt> } ] + [ hdr <name> <value> ]* + [ { if | unless } <condition> ] + + This stops the evaluation of the rules and immediately returns a + response. Please refer to "http-request return" for a complete + description. No further "http-response" rules are evaluated. + +http-response sc-inc-gpc(<idx>,<sc-id>) [ { if | unless } <condition> ] +http-response sc-inc-gpc0(<sc-id>) [ { if | unless } <condition> ] +http-response sc-inc-gpc1(<sc-id>) [ { if | unless } <condition> ] + + These actions increment the General Purppose Counters according to the sticky + counter designated by <sc-id>. Please refer to "http-request sc-inc-gpc", + "http-request sc-inc-gpc0" and "http-request sc-inc-gpc1" for a complete + description. + +http-response sc-set-gpt(<idx>,<sc-id>) { <int> | <expr> } + [ { if | unless } <condition> ] +http-response sc-set-gpt0(<sc-id>) { <int> | <expr> } + [ { if | unless } <condition> ] + + These actions set the 32-bit unsigned General Purpose Tags according to the + sticky counter designated by <sc-id>. Please refer to "http-request + sc-inc-gpt" and "http-request sc-inc-gpt0" for a complete description. + +http-response send-spoe-group <engine-name> <group-name> + [ { if | unless } <condition> ] + + This action is used to trigger sending of a group of SPOE messages. Please + refer to "http-request send-spoe-group" for a complete description. + +http-response set-header <name> <fmt> [ { if | unless } <condition> ] + + This does the same as "http-response add-header" except that the header name + is first removed if it existed. This is useful when passing security + information to the server, where the header must not be manipulated by + external users. + +http-response set-log-level <level> [ { if | unless } <condition> ] + + This is used to change the log level of the current response. Please refer to + "http-request set-log-level" for a complete description. + +http-response set-map(<file-name>) <key fmt> <value fmt> + + This is used to add a new entry into a MAP. Please refer to "http-request + set-map" for a complete description. + +http-response set-mark <mark> [ { if | unless } <condition> ] + + This action is used to set the Netfilter/IPFW MARK in all packets sent to the + client to the value passed in <mark> on platforms which support it. Please + refer to "http-request set-mark" for a complete description. + +http-response set-nice <nice> [ { if | unless } <condition> ] + + This sets the "nice" factor of the current request being processed. Please + refer to "http-request set-nice" for a complete description. + +http-response set-status <status> [reason <str>] + [ { if | unless } <condition> ] + + This replaces the response status code with <status> which must be an integer + between 100 and 999. Optionally, a custom reason text can be provided defined + by <str>, or the default reason for the specified code will be used as a + fallback. + + Example: + # return "431 Request Header Fields Too Large" + http-response set-status 431 + # return "503 Slow Down", custom reason + http-response set-status 503 reason "Slow Down". + +http-response set-tos <tos> [ { if | unless } <condition> ] + + This is used to set the TOS or DSCP field value of packets sent to the client + to the value passed in <tos> on platforms which support this. Please refer to + "http-request set-tos" for a complete description. + +http-response set-var(<var-name>[,<cond>...]) <expr> [ { if | unless } <condition> ] +http-response set-var-fmt(<var-name>[,<cond>...]) <fmt> [ { if | unless } <condition> ] + + This is used to set the contents of a variable. The variable is declared + inline. Please refer to "http-request set-var" and "http-request set-var-fmt" + for a complete description. + +http-response silent-drop [ { if | unless } <condition> ] + + This stops the evaluation of the rules and makes the client-facing connection + suddenly disappear using a system-dependent way that tries to prevent the + client from being notified. Please refer to "http-request silent-drop" for a + complete description. + +http-response strict-mode { on | off } [ { if | unless } <condition> ] + + This enables or disables the strict rewriting mode for following + rules. Please refer to "http-request strict-mode" for a complete description. + +http-response track-sc0 <key> [table <table>] [ { if | unless } <condition> ] +http-response track-sc1 <key> [table <table>] [ { if | unless } <condition> ] +http-response track-sc2 <key> [table <table>] [ { if | unless } <condition> ] + + This enables tracking of sticky counters from current connection. Please + refer to "http-request track-sc0", "http-request track-sc1" and "http-request + track-sc2" for a complete description. + +http-response unset-var(<var-name>) [ { if | unless } <condition> ] + + This is used to unset a variable. See "http-request set-var" for details + about <var-name>. + +http-response wait-for-body time <time> [ at-least <bytes> ] + [ { if | unless } <condition> ] + + This will delay the processing of the response waiting for the payload for at + most <time> milliseconds. Please refer to "http-request wait-for-body" for a + complete description. + + +http-reuse { never | safe | aggressive | always } + Declare how idle HTTP connections may be shared between requests + + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + + By default, a connection established between HAProxy and the backend server + which is considered safe for reuse is moved back to the server's idle + connections pool so that any other request can make use of it. This is the + "safe" strategy below. + + The argument indicates the desired connection reuse strategy : + + - "never" : idle connections are never shared between sessions. This mode + may be enforced to cancel a different strategy inherited from + a defaults section or for troubleshooting. For example, if an + old bogus application considers that multiple requests over + the same connection come from the same client and it is not + possible to fix the application, it may be desirable to + disable connection sharing in a single backend. An example of + such an application could be an old HAProxy using cookie + insertion in tunnel mode and not checking any request past the + first one. + + - "safe" : this is the default and the recommended strategy. The first + request of a session is always sent over its own connection, + and only subsequent requests may be dispatched over other + existing connections. This ensures that in case the server + closes the connection when the request is being sent, the + browser can decide to silently retry it. Since it is exactly + equivalent to regular keep-alive, there should be no side + effects. There is also a special handling for the connections + using protocols subject to Head-of-line blocking (backend with + h2 or fcgi). In this case, when at least one stream is + processed, the used connection is reserved to handle streams + of the same session. When no more streams are processed, the + connection is released and can be reused. + + - "aggressive" : this mode may be useful in webservices environments where + all servers are not necessarily known and where it would be + appreciable to deliver most first requests over existing + connections. In this case, first requests are only delivered + over existing connections that have been reused at least once, + proving that the server correctly supports connection reuse. + It should only be used when it's sure that the client can + retry a failed request once in a while and where the benefit + of aggressive connection reuse significantly outweighs the + downsides of rare connection failures. + + - "always" : this mode is only recommended when the path to the server is + known for never breaking existing connections quickly after + releasing them. It allows the first request of a session to be + sent to an existing connection. This can provide a significant + performance increase over the "safe" strategy when the backend + is a cache farm, since such components tend to show a + consistent behavior and will benefit from the connection + sharing. It is recommended that the "http-keep-alive" timeout + remains low in this mode so that no dead connections remain + usable. In most cases, this will lead to the same performance + gains as "aggressive" but with more risks. It should only be + used when it improves the situation over "aggressive". + + When http connection sharing is enabled, a great care is taken to respect the + connection properties and compatibility. Indeed, some properties are specific + and it is not possibly to reuse it blindly. Those are the SSL SNI, source + and destination address and proxy protocol block. A connection is reused only + if it shares the same set of properties with the request. + + Also note that connections with certain bogus authentication schemes (relying + on the connection) like NTLM are marked private and never shared. + + A connection pool is involved and configurable with "pool-max-conn". + + Note: connection reuse improves the accuracy of the "server maxconn" setting, + because almost no new connection will be established while idle connections + remain available. This is particularly true with the "always" strategy. + + The rules to decide to keep an idle connection opened or to close it after + processing are also governed by the "tune.pool-low-fd-ratio" (default: 20%) + and "tune.pool-high-fd-ratio" (default: 25%). These correspond to the + percentage of total file descriptors spent in idle connections above which + haproxy will respectively refrain from keeping a connection opened after a + response, and actively kill idle connections. Some setups using a very high + ratio of idle connections, either because of too low a global "maxconn", or + due to a lot of HTTP/2 or HTTP/3 traffic on the frontend (few connections) + but HTTP/1 connections on the backend, may observe a lower reuse rate because + too few connections are kept open. It may be desirable in this case to adjust + such thresholds or simply to increase the global "maxconn" value. + + Similarly, when thread groups are explicitly enabled, it is important to + understand that idle connections are only usable between threads from a same + group. As such it may happen that unfair load between groups leads to more + idle connections being needed, causing a lower reuse rate. The same solution + may then be applied (increase global "maxconn" or increase pool ratios). + + See also : "option http-keep-alive", "server maxconn", "thread-groups", + "tune.pool-high-fd-ratio", "tune.pool-low-fd-ratio" + + +http-send-name-header [<header>] + Add the server name to a request. Use the header string given by <header> + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <header> The header string to use to send the server name + + The "http-send-name-header" statement causes the header field named <header> + to be set to the name of the target server at the moment the request is about + to be sent on the wire. Any existing occurrences of this header are removed. + Upon retries and redispatches, the header field is updated to always reflect + the server being attempted to connect to. Given that this header is modified + very late in the connection setup, it may have unexpected effects on already + modified headers. For example using it with transport-level header such as + connection, content-length, transfer-encoding and so on will likely result in + invalid requests being sent to the server. Additionally it has been reported + that this directive is currently being used as a way to overwrite the Host + header field in outgoing requests; while this trick has been known to work + as a side effect of the feature for some time, it is not officially supported + and might possibly not work anymore in a future version depending on the + technical difficulties this feature induces. A long-term solution instead + consists in fixing the application which required this trick so that it binds + to the correct host name. + + See also : "server" + +id <value> + Set a persistent ID to a proxy. + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | yes + Arguments : none + + Set a persistent ID for the proxy. This ID must be unique and positive. + An unused ID will automatically be assigned if unset. The first assigned + value will be 1. This ID is currently only returned in statistics. + + +ignore-persist { if | unless } <condition> + Declare a condition to ignore persistence + May be used in sections: defaults | frontend | listen | backend + no | no | yes | yes + + By default, when cookie persistence is enabled, every requests containing + the cookie are unconditionally persistent (assuming the target server is up + and running). + + The "ignore-persist" statement allows one to declare various ACL-based + conditions which, when met, will cause a request to ignore persistence. + This is sometimes useful to load balance requests for static files, which + often don't require persistence. This can also be used to fully disable + persistence for a specific User-Agent (for example, some web crawler bots). + + The persistence is ignored when an "if" condition is met, or unless an + "unless" condition is met. + + Example: + acl url_static path_beg /static /images /img /css + acl url_static path_end .gif .png .jpg .css .js + ignore-persist if url_static + + See also : "force-persist", "cookie", and section 7 about ACL usage. + +load-server-state-from-file { global | local | none } + Allow seamless reload of HAProxy + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + + This directive points HAProxy to a file where server state from previous + running process has been saved. That way, when starting up, before handling + traffic, the new process can apply old states to servers exactly has if no + reload occurred. The purpose of the "load-server-state-from-file" directive is + to tell HAProxy which file to use. For now, only 2 arguments to either prevent + loading state or load states from a file containing all backends and servers. + The state file can be generated by running the command "show servers state" + over the stats socket and redirect output. + + The format of the file is versioned and is very specific. To understand it, + please read the documentation of the "show servers state" command (chapter + 9.3 of Management Guide). + + Arguments: + global load the content of the file pointed by the global directive + named "server-state-file". + + local load the content of the file pointed by the directive + "server-state-file-name" if set. If not set, then the backend + name is used as a file name. + + none don't load any stat for this backend + + Notes: + - server's IP address is preserved across reloads by default, but the + order can be changed thanks to the server's "init-addr" setting. This + means that an IP address change performed on the CLI at run time will + be preserved, and that any change to the local resolver (e.g. /etc/hosts) + will possibly not have any effect if the state file is in use. + + - server's weight is applied from previous running process unless it has + has changed between previous and new configuration files. + + Example: Minimal configuration + + global + stats socket /tmp/socket + server-state-file /tmp/server_state + + defaults + load-server-state-from-file global + + backend bk + server s1 127.0.0.1:22 check weight 11 + server s2 127.0.0.1:22 check weight 12 + + + Then one can run : + + socat /tmp/socket - <<< "show servers state" > /tmp/server_state + + Content of the file /tmp/server_state would be like this: + + 1 + # <field names skipped for the doc example> + 1 bk 1 s1 127.0.0.1 2 0 11 11 4 6 3 4 6 0 0 + 1 bk 2 s2 127.0.0.1 2 0 12 12 4 6 3 4 6 0 0 + + Example: Minimal configuration + + global + stats socket /tmp/socket + server-state-base /etc/haproxy/states + + defaults + load-server-state-from-file local + + backend bk + server s1 127.0.0.1:22 check weight 11 + server s2 127.0.0.1:22 check weight 12 + + + Then one can run : + + socat /tmp/socket - <<< "show servers state bk" > /etc/haproxy/states/bk + + Content of the file /etc/haproxy/states/bk would be like this: + + 1 + # <field names skipped for the doc example> + 1 bk 1 s1 127.0.0.1 2 0 11 11 4 6 3 4 6 0 0 + 1 bk 2 s2 127.0.0.1 2 0 12 12 4 6 3 4 6 0 0 + + See also: "server-state-file", "server-state-file-name", and + "show servers state" + + +log global +log <address> [len <length>] [format <format>] [sample <ranges>:<sample_size>] + <facility> [<level> [<minlevel>]] +no log + Enable per-instance logging of events and traffic. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + + Prefix : + no should be used when the logger list must be flushed. For example, + if you don't want to inherit from the default logger list. This + prefix does not allow arguments. + + Arguments : + global should be used when the instance's logging parameters are the + same as the global ones. This is the most common usage. "global" + replaces <address>, <facility> and <level> with those of the log + entries found in the "global" section. Only one "log global" + statement may be used per instance, and this form takes no other + parameter. + + <address> indicates where to send the logs. It takes the same format as + for the "global" section's logs, and can be one of : + + - An IPv4 address optionally followed by a colon (':') and a UDP + port. If no port is specified, 514 is used by default (the + standard syslog port). + + - An IPv6 address followed by a colon (':') and optionally a UDP + port. If no port is specified, 514 is used by default (the + standard syslog port). + + - A filesystem path to a UNIX domain socket, keeping in mind + considerations for chroot (be sure the path is accessible + inside the chroot) and uid/gid (be sure the path is + appropriately writable). + + - A file descriptor number in the form "fd@<number>", which may + point to a pipe, terminal, or socket. In this case unbuffered + logs are used and one writev() call per log is performed. This + is a bit expensive but acceptable for most workloads. Messages + sent this way will not be truncated but may be dropped, in + which case the DroppedLogs counter will be incremented. The + writev() call is atomic even on pipes for messages up to + PIPE_BUF size, which POSIX recommends to be at least 512 and + which is 4096 bytes on most modern operating systems. Any + larger message may be interleaved with messages from other + processes. Exceptionally for debugging purposes the file + descriptor may also be directed to a file, but doing so will + significantly slow HAProxy down as non-blocking calls will be + ignored. Also there will be no way to purge nor rotate this + file without restarting the process. Note that the configured + syslog format is preserved, so the output is suitable for use + with a TCP syslog server. See also the "short" and "raw" + formats below. + + - "stdout" / "stderr", which are respectively aliases for "fd@1" + and "fd@2", see above. + + - A ring buffer in the form "ring@<name>", which will correspond + to an in-memory ring buffer accessible over the CLI using the + "show events" command, which will also list existing rings and + their sizes. Such buffers are lost on reload or restart but + when used as a complement this can help troubleshooting by + having the logs instantly available. + + - An explicit stream address prefix such as "tcp@","tcp6@", + "tcp4@" or "uxst@" will allocate an implicit ring buffer with + a stream forward server targeting the given address. + + You may want to reference some environment variables in the + address parameter, see section 2.3 about environment variables. + + <length> is an optional maximum line length. Log lines larger than this + value will be truncated before being sent. The reason is that + syslog servers act differently on log line length. All servers + support the default value of 1024, but some servers simply drop + larger lines while others do log them. If a server supports long + lines, it may make sense to set this value here in order to avoid + truncating long lines. Similarly, if a server drops long lines, + it is preferable to truncate them before sending them. Accepted + values are 80 to 65535 inclusive. The default value of 1024 is + generally fine for all standard usages. Some specific cases of + long captures or JSON-formatted logs may require larger values. + + <ranges> A list of comma-separated ranges to identify the logs to sample. + This is used to balance the load of the logs to send to the log + server. The limits of the ranges cannot be null. They are numbered + from 1. The size or period (in number of logs) of the sample must + be set with <sample_size> parameter. + + <sample_size> + The size of the sample in number of logs to consider when balancing + their logging loads. It is used to balance the load of the logs to + send to the syslog server. This size must be greater or equal to the + maximum of the high limits of the ranges. + (see also <ranges> parameter). + + <format> is the log format used when generating syslog messages. It may be + one of the following : + + local Analog to rfc3164 syslog message format except that hostname + field is stripped. This is the default. + Note: option "log-send-hostname" switches the default to + rfc3164. + + rfc3164 The RFC3164 syslog message format. + (https://tools.ietf.org/html/rfc3164) + + rfc5424 The RFC5424 syslog message format. + (https://tools.ietf.org/html/rfc5424) + + priority A message containing only a level plus syslog facility between + angle brackets such as '<63>', followed by the text. The PID, + date, time, process name and system name are omitted. This is + designed to be used with a local log server. + + short A message containing only a level between angle brackets such as + '<3>', followed by the text. The PID, date, time, process name + and system name are omitted. This is designed to be used with a + local log server. This format is compatible with what the + systemd logger consumes. + + timed A message containing only a level between angle brackets such as + '<3>', followed by ISO date and by the text. The PID, process + name and system name are omitted. This is designed to be + used with a local log server. + + iso A message containing only the ISO date, followed by the text. + The PID, process name and system name are omitted. This is + designed to be used with a local log server. + + raw A message containing only the text. The level, PID, date, time, + process name and system name are omitted. This is designed to + be used in containers or during development, where the severity + only depends on the file descriptor used (stdout/stderr). + + <facility> must be one of the 24 standard syslog facilities : + + kern user mail daemon auth syslog lpr news + uucp cron auth2 ftp ntp audit alert cron2 + local0 local1 local2 local3 local4 local5 local6 local7 + + Note that the facility is ignored for the "short" and "raw" + formats, but still required as a positional field. It is + recommended to use "daemon" in this case to make it clear that + it's only supposed to be used locally. + + <level> is optional and can be specified to filter outgoing messages. By + default, all messages are sent. If a level is specified, only + messages with a severity at least as important as this level + will be sent. An optional minimum level can be specified. If it + is set, logs emitted with a more severe level than this one will + be capped to this level. This is used to avoid sending "emerg" + messages on all terminals on some default syslog configurations. + Eight levels are known : + + emerg alert crit err warning notice info debug + + It is important to keep in mind that it is the frontend which decides what to + log from a connection, and that in case of content switching, the log entries + from the backend will be ignored. Connections are logged at level "info". + + However, backend log declaration define how and where servers status changes + will be logged. Level "notice" will be used to indicate a server going up, + "warning" will be used for termination signals and definitive service + termination, and "alert" will be used for when a server goes down. + + Note : According to RFC3164, messages are truncated to 1024 bytes before + being emitted. + + Example : + log global + log stdout format short daemon # send log to systemd + log stdout format raw daemon # send everything to stdout + log stderr format raw daemon notice # send important events to stderr + log 127.0.0.1:514 local0 notice # only send important events + log tcp@127.0.0.1:514 local0 notice notice # same but limit output + # level and send in tcp + log "${LOCAL_SYSLOG}:514" local0 notice # send to local server + + +log-format <string> + Specifies the log format string to use for traffic logs + May be used in sections: defaults | frontend | listen | backend + yes | yes | yes | no + + This directive specifies the log format string that will be used for all logs + resulting from traffic passing through the frontend using this line. If the + directive is used in a defaults section, all subsequent frontends will use + the same log format. Please see section 8.2.4 which covers the log format + string in depth. + A specific log-format used only in case of connection error can also be + defined, see the "error-log-format" option. + + "log-format" directive overrides previous "option tcplog", "log-format", + "option httplog" and "option httpslog" directives. + +log-format-sd <string> + Specifies the RFC5424 structured-data log format string + May be used in sections: defaults | frontend | listen | backend + yes | yes | yes | no + + This directive specifies the RFC5424 structured-data log format string that + will be used for all logs resulting from traffic passing through the frontend + using this line. If the directive is used in a defaults section, all + subsequent frontends will use the same log format. Please see section 8.2.4 + which covers the log format string in depth. + + See https://tools.ietf.org/html/rfc5424#section-6.3 for more information + about the RFC5424 structured-data part. + + Note : This log format string will be used only for loggers that have set + log format to "rfc5424". + + Example : + log-format-sd [exampleSDID@1234\ bytes=\"%B\"\ status=\"%ST\"] + + +log-tag <string> + Specifies the log tag to use for all outgoing logs + May be used in sections: defaults | frontend | listen | backend + yes | yes | yes | yes + + Sets the tag field in the syslog header to this string. It defaults to the + log-tag set in the global section, otherwise the program name as launched + from the command line, which usually is "HAProxy". Sometimes it can be useful + to differentiate between multiple processes running on the same host, or to + differentiate customer instances running in the same process. In the backend, + logs about servers up/down will use this tag. As a hint, it can be convenient + to set a log-tag related to a hosted customer in a defaults section then put + all the frontends and backends for that customer, then start another customer + in a new defaults section. See also the global "log-tag" directive. + +max-keep-alive-queue <value> + Set the maximum server queue size for maintaining keep-alive connections + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + + HTTP keep-alive tries to reuse the same server connection whenever possible, + but sometimes it can be counter-productive, for example if a server has a lot + of connections while other ones are idle. This is especially true for static + servers. + + The purpose of this setting is to set a threshold on the number of queued + connections at which HAProxy stops trying to reuse the same server and prefers + to find another one. The default value, -1, means there is no limit. A value + of zero means that keep-alive requests will never be queued. For very close + servers which can be reached with a low latency and which are not sensible to + breaking keep-alive, a low value is recommended (e.g. local static server can + use a value of 10 or less). For remote servers suffering from a high latency, + higher values might be needed to cover for the latency and/or the cost of + picking a different server. + + Note that this has no impact on responses which are maintained to the same + server consecutively to a 401 response. They will still go to the same server + even if they have to be queued. + + See also : "option http-server-close", "option prefer-last-server", server + "maxconn" and cookie persistence. + +max-session-srv-conns <nb> + Set the maximum number of outgoing connections we can keep idling for a given + client session. The default is 5 (it precisely equals MAX_SRV_LIST which is + defined at build time). + +maxconn <conns> + Fix the maximum number of concurrent connections on a frontend + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : + <conns> is the maximum number of concurrent connections the frontend will + accept to serve. Excess connections will be queued by the system + in the socket's listen queue and will be served once a connection + closes. + + If the system supports it, it can be useful on big sites to raise this limit + very high so that HAProxy manages connection queues, instead of leaving the + clients with unanswered connection attempts. This value should not exceed the + global maxconn. Also, keep in mind that a connection contains two buffers + of tune.bufsize (16kB by default) each, as well as some other data resulting + in about 33 kB of RAM being consumed per established connection. That means + that a medium system equipped with 1GB of RAM can withstand around + 20000-25000 concurrent connections if properly tuned. + + Also, when <conns> is set to large values, it is possible that the servers + are not sized to accept such loads, and for this reason it is generally wise + to assign them some reasonable connection limits. + + When this value is set to zero, which is the default, the global "maxconn" + value is used. + + See also : "server", global section's "maxconn", "fullconn" + + +mode { tcp|http } + Set the running mode or protocol of the instance + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + tcp The instance will work in pure TCP mode. A full-duplex connection + will be established between clients and servers, and no layer 7 + examination will be performed. This is the default mode. It + should be used for SSL, SSH, SMTP, ... + + http The instance will work in HTTP mode. The client request will be + analyzed in depth before connecting to any server. Any request + which is not RFC-compliant will be rejected. Layer 7 filtering, + processing and switching will be possible. This is the mode which + brings HAProxy most of its value. + + When doing content switching, it is mandatory that the frontend and the + backend are in the same mode (generally HTTP), otherwise the configuration + will be refused. + + Example : + defaults http_instances + mode http + + +monitor fail { if | unless } <condition> + Add a condition to report a failure to a monitor HTTP request. + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | no + Arguments : + if <cond> the monitor request will fail if the condition is satisfied, + and will succeed otherwise. The condition should describe a + combined test which must induce a failure if all conditions + are met, for instance a low number of servers both in a + backend and its backup. + + unless <cond> the monitor request will succeed only if the condition is + satisfied, and will fail otherwise. Such a condition may be + based on a test on the presence of a minimum number of active + servers in a list of backends. + + This statement adds a condition which can force the response to a monitor + request to report a failure. By default, when an external component queries + the URI dedicated to monitoring, a 200 response is returned. When one of the + conditions above is met, HAProxy will return 503 instead of 200. This is + very useful to report a site failure to an external component which may base + routing advertisements between multiple sites on the availability reported by + HAProxy. In this case, one would rely on an ACL involving the "nbsrv" + criterion. Note that "monitor fail" only works in HTTP mode. Both status + messages may be tweaked using "errorfile" or "errorloc" if needed. + + Example: + frontend www + mode http + acl site_dead nbsrv(dynamic) lt 2 + acl site_dead nbsrv(static) lt 2 + monitor-uri /site_alive + monitor fail if site_dead + + See also : "monitor-uri", "errorfile", "errorloc" + + +monitor-uri <uri> + Intercept a URI used by external components' monitor requests + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : + <uri> is the exact URI which we want to intercept to return HAProxy's + health status instead of forwarding the request. + + When an HTTP request referencing <uri> will be received on a frontend, + HAProxy will not forward it nor log it, but instead will return either + "HTTP/1.0 200 OK" or "HTTP/1.0 503 Service unavailable", depending on failure + conditions defined with "monitor fail". This is normally enough for any + front-end HTTP probe to detect that the service is UP and running without + forwarding the request to a backend server. Note that the HTTP method, the + version and all headers are ignored, but the request must at least be valid + at the HTTP level. This keyword may only be used with an HTTP-mode frontend. + + Monitor requests are processed very early, just after the request is parsed + and even before any "http-request". The only rulesets applied before are the + tcp-request ones. They cannot be logged either, and it is the intended + purpose. Only one URI may be configured for monitoring; when multiple + "monitor-uri" statements are present, the last one will define the URI to + be used. They are only used to report HAProxy's health to an upper component, + nothing more. However, it is possible to add any number of conditions using + "monitor fail" and ACLs so that the result can be adjusted to whatever check + can be imagined (most often the number of available servers in a backend). + + Note: if <uri> starts by a slash ('/'), the matching is performed against the + request's path instead of the request's uri. It is a workaround to let + the HTTP/2 requests match the monitor-uri. Indeed, in HTTP/2, clients + are encouraged to send absolute URIs only. + + Example : + # Use /haproxy_test to report HAProxy's status + frontend www + mode http + monitor-uri /haproxy_test + + See also : "monitor fail" + + +option abortonclose +no option abortonclose + Enable or disable early dropping of aborted requests pending in queues. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + In presence of very high loads, the servers will take some time to respond. + The per-instance connection queue will inflate, and the response time will + increase respective to the size of the queue times the average per-session + response time. When clients will wait for more than a few seconds, they will + often hit the "STOP" button on their browser, leaving a useless request in + the queue, and slowing down other users, and the servers as well, because the + request will eventually be served, then aborted at the first error + encountered while delivering the response. + + As there is no way to distinguish between a full STOP and a simple output + close on the client side, HTTP agents should be conservative and consider + that the client might only have closed its output channel while waiting for + the response. However, this introduces risks of congestion when lots of users + do the same, and is completely useless nowadays because probably no client at + all will close the session while waiting for the response. Some HTTP agents + support this behavior (Squid, Apache, HAProxy), and others do not (TUX, most + hardware-based load balancers). So the probability for a closed input channel + to represent a user hitting the "STOP" button is close to 100%, and the risk + of being the single component to break rare but valid traffic is extremely + low, which adds to the temptation to be able to abort a session early while + still not served and not pollute the servers. + + In HAProxy, the user can choose the desired behavior using the option + "abortonclose". By default (without the option) the behavior is HTTP + compliant and aborted requests will be served. But when the option is + specified, a session with an incoming channel closed will be aborted while + it is still possible, either pending in the queue for a connection slot, or + during the connection establishment if the server has not yet acknowledged + the connection request. This considerably reduces the queue size and the load + on saturated servers when users are tempted to click on STOP, which in turn + reduces the response time for other users. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "timeout queue" and server's "maxconn" and "maxqueue" parameters + + +option accept-invalid-http-request +no option accept-invalid-http-request + Enable or disable relaxing of HTTP request parsing + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + By default, HAProxy complies with RFC7230 in terms of message parsing. This + means that invalid characters in header names are not permitted and cause an + error to be returned to the client. This is the desired behavior as such + forbidden characters are essentially used to build attacks exploiting server + weaknesses, and bypass security filtering. Sometimes, a buggy browser or + server will emit invalid header names for whatever reason (configuration, + implementation) and the issue will not be immediately fixed. In such a case, + it is possible to relax HAProxy's header name parser to accept any character + even if that does not make sense, by specifying this option. Similarly, the + list of characters allowed to appear in a URI is well defined by RFC3986, and + chars 0-31, 32 (space), 34 ('"'), 60 ('<'), 62 ('>'), 92 ('\'), 94 ('^'), 96 + ('`'), 123 ('{'), 124 ('|'), 125 ('}'), 127 (delete) and anything above are + not allowed at all. HAProxy always blocks a number of them (0..32, 127). The + remaining ones are blocked by default unless this option is enabled. This + option also relaxes the test on the HTTP version, it allows HTTP/0.9 requests + to pass through (no version specified), as well as different protocol names + (e.g. RTSP), and multiple digits for both the major and the minor version. + + This option should never be enabled by default as it hides application bugs + and open security breaches. It should only be deployed after a problem has + been confirmed. + + When this option is enabled, erroneous header names will still be accepted in + requests, but the complete request will be captured in order to permit later + analysis using the "show errors" request on the UNIX stats socket. Similarly, + requests containing invalid chars in the URI part will be logged. Doing this + also helps confirming that the issue has been solved. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "option accept-invalid-http-response" and "show errors" on the + stats socket. + + +option accept-invalid-http-response +no option accept-invalid-http-response + Enable or disable relaxing of HTTP response parsing + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + By default, HAProxy complies with RFC7230 in terms of message parsing. This + means that invalid characters in header names are not permitted and cause an + error to be returned to the client. This is the desired behavior as such + forbidden characters are essentially used to build attacks exploiting server + weaknesses, and bypass security filtering. Sometimes, a buggy browser or + server will emit invalid header names for whatever reason (configuration, + implementation) and the issue will not be immediately fixed. In such a case, + it is possible to relax HAProxy's header name parser to accept any character + even if that does not make sense, by specifying this option. This option also + relaxes the test on the HTTP version format, it allows multiple digits for + both the major and the minor version. + + This option should never be enabled by default as it hides application bugs + and open security breaches. It should only be deployed after a problem has + been confirmed. + + When this option is enabled, erroneous header names will still be accepted in + responses, but the complete response will be captured in order to permit + later analysis using the "show errors" request on the UNIX stats socket. + Doing this also helps confirming that the issue has been solved. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "option accept-invalid-http-request" and "show errors" on the + stats socket. + + +option allbackups +no option allbackups + Use either all backup servers at a time or only the first one + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + By default, the first operational backup server gets all traffic when normal + servers are all down. Sometimes, it may be preferred to use multiple backups + at once, because one will not be enough. When "option allbackups" is enabled, + the load balancing will be performed among all backup servers when all normal + ones are unavailable. The same load balancing algorithm will be used and the + servers' weights will be respected. Thus, there will not be any priority + order between the backup servers anymore. + + This option is mostly used with static server farms dedicated to return a + "sorry" page when an application is completely offline. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + +option checkcache +no option checkcache + Analyze all server responses and block responses with cacheable cookies + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + Some high-level frameworks set application cookies everywhere and do not + always let enough control to the developer to manage how the responses should + be cached. When a session cookie is returned on a cacheable object, there is a + high risk of session crossing or stealing between users traversing the same + caches. In some situations, it is better to block the response than to let + some sensitive session information go in the wild. + + The option "checkcache" enables deep inspection of all server responses for + strict compliance with HTTP specification in terms of cacheability. It + carefully checks "Cache-control", "Pragma" and "Set-cookie" headers in server + response to check if there's a risk of caching a cookie on a client-side + proxy. When this option is enabled, the only responses which can be delivered + to the client are : + - all those without "Set-Cookie" header; + - all those with a return code other than 200, 203, 204, 206, 300, 301, + 404, 405, 410, 414, 501, provided that the server has not set a + "Cache-control: public" header field; + - all those that result from a request using a method other than GET, HEAD, + OPTIONS, TRACE, provided that the server has not set a 'Cache-Control: + public' header field; + - those with a 'Pragma: no-cache' header + - those with a 'Cache-control: private' header + - those with a 'Cache-control: no-store' header + - those with a 'Cache-control: max-age=0' header + - those with a 'Cache-control: s-maxage=0' header + - those with a 'Cache-control: no-cache' header + - those with a 'Cache-control: no-cache="set-cookie"' header + - those with a 'Cache-control: no-cache="set-cookie,' header + (allowing other fields after set-cookie) + + If a response doesn't respect these requirements, then it will be blocked + just as if it was from an "http-response deny" rule, with an "HTTP 502 bad + gateway". The session state shows "PH--" meaning that the proxy blocked the + response during headers processing. Additionally, an alert will be sent in + the logs so that admins are informed that there's something to be fixed. + + Due to the high impact on the application, the application should be tested + in depth with the option enabled before going to production. It is also a + good practice to always activate it during tests, even if it is not used in + production, as it will report potentially dangerous application behaviors. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + +option clitcpka +no option clitcpka + Enable or disable the sending of TCP keepalive packets on the client side + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + When there is a firewall or any session-aware component between a client and + a server, and when the protocol involves very long sessions with long idle + periods (e.g. remote desktops), there is a risk that one of the intermediate + components decides to expire a session which has remained idle for too long. + + Enabling socket-level TCP keep-alives makes the system regularly send packets + to the other end of the connection, leaving it active. The delay between + keep-alive probes is controlled by the system only and depends both on the + operating system and its tuning parameters. + + It is important to understand that keep-alive packets are neither emitted nor + received at the application level. It is only the network stacks which sees + them. For this reason, even if one side of the proxy already uses keep-alives + to maintain its connection alive, those keep-alive packets will not be + forwarded to the other side of the proxy. + + Please note that this has nothing to do with HTTP keep-alive. + + Using option "clitcpka" enables the emission of TCP keep-alive probes on the + client side of a connection, which should help when session expirations are + noticed between HAProxy and a client. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "option srvtcpka", "option tcpka" + + +option contstats + Enable continuous traffic statistics updates + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + By default, counters used for statistics calculation are incremented + only when a session finishes. It works quite well when serving small + objects, but with big ones (for example large images or archives) or + with A/V streaming, a graph generated from HAProxy counters looks like + a hedgehog. With this option enabled counters get incremented frequently + along the session, typically every 5 seconds, which is often enough to + produce clean graphs. Recounting touches a hotpath directly so it is not + not enabled by default, as it can cause a lot of wakeups for very large + session counts and cause a small performance drop. + +option disable-h2-upgrade +no option disable-h2-upgrade + Enable or disable the implicit HTTP/2 upgrade from an HTTP/1.x client + connection. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + By default, HAProxy is able to implicitly upgrade an HTTP/1.x client + connection to an HTTP/2 connection if the first request it receives from a + given HTTP connection matches the HTTP/2 connection preface (i.e. the string + "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"). This way, it is possible to support + HTTP/1.x and HTTP/2 clients on a non-SSL connections. This option must be + used to disable the implicit upgrade. Note this implicit upgrade is only + supported for HTTP proxies, thus this option too. Note also it is possible to + force the HTTP/2 on clear connections by specifying "proto h2" on the bind + line. Finally, this option is applied on all bind lines. To disable implicit + HTTP/2 upgrades for a specific bind line, it is possible to use "proto h1". + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + +option dontlog-normal +no option dontlog-normal + Enable or disable logging of normal, successful connections + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + There are large sites dealing with several thousand connections per second + and for which logging is a major pain. Some of them are even forced to turn + logs off and cannot debug production issues. Setting this option ensures that + normal connections, those which experience no error, no timeout, no retry nor + redispatch, will not be logged. This leaves disk space for anomalies. In HTTP + mode, the response status code is checked and return codes 5xx will still be + logged. + + It is strongly discouraged to use this option as most of the time, the key to + complex issues is in the normal logs which will not be logged here. If you + need to separate logs, see the "log-separate-errors" option instead. + + See also : "log", "dontlognull", "log-separate-errors" and section 8 about + logging. + + +option dontlognull +no option dontlognull + Enable or disable logging of null connections + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + In certain environments, there are components which will regularly connect to + various systems to ensure that they are still alive. It can be the case from + another load balancer as well as from monitoring systems. By default, even a + simple port probe or scan will produce a log. If those connections pollute + the logs too much, it is possible to enable option "dontlognull" to indicate + that a connection on which no data has been transferred will not be logged, + which typically corresponds to those probes. Note that errors will still be + returned to the client and accounted for in the stats. If this is not what is + desired, option http-ignore-probes can be used instead. + + It is generally recommended not to use this option in uncontrolled + environments (e.g. internet), otherwise scans and other malicious activities + would not be logged. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "log", "http-ignore-probes", "monitor-uri", and + section 8 about logging. + + +option forwardfor [ except <network> ] [ header <name> ] [ if-none ] + Enable insertion of the X-Forwarded-For header to requests sent to servers + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <network> is an optional argument used to disable this option for sources + matching <network> + <name> an optional argument to specify a different "X-Forwarded-For" + header name. + + Since HAProxy works in reverse-proxy mode, the servers see its IP address as + their client address. This is sometimes annoying when the client's IP address + is expected in server logs. To solve this problem, the well-known HTTP header + "X-Forwarded-For" may be added by HAProxy to all requests sent to the server. + This header contains a value representing the client's IP address. Since this + header is always appended at the end of the existing header list, the server + must be configured to always use the last occurrence of this header only. See + the server's manual to find how to enable use of this standard header. Note + that only the last occurrence of the header must be used, since it is really + possible that the client has already brought one. + + The keyword "header" may be used to supply a different header name to replace + the default "X-Forwarded-For". This can be useful where you might already + have a "X-Forwarded-For" header from a different application (e.g. stunnel), + and you need preserve it. Also if your backend server doesn't use the + "X-Forwarded-For" header and requires different one (e.g. Zeus Web Servers + require "X-Cluster-Client-IP"). + + Sometimes, a same HAProxy instance may be shared between a direct client + access and a reverse-proxy access (for instance when an SSL reverse-proxy is + used to decrypt HTTPS traffic). It is possible to disable the addition of the + header for a known source address or network by adding the "except" keyword + followed by the network address. In this case, any source IP matching the + network will not cause an addition of this header. Most common uses are with + private networks or 127.0.0.1. IPv4 and IPv6 are both supported. + + Alternatively, the keyword "if-none" states that the header will only be + added if it is not present. This should only be used in perfectly trusted + environment, as this might cause a security issue if headers reaching HAProxy + are under the control of the end-user. + + This option may be specified either in the frontend or in the backend. If at + least one of them uses it, the header will be added. Note that the backend's + setting of the header subargument takes precedence over the frontend's if + both are defined. In the case of the "if-none" argument, if at least one of + the frontend or the backend does not specify it, it wants the addition to be + mandatory, so it wins. + + Example : + # Public HTTP address also used by stunnel on the same machine + frontend www + mode http + option forwardfor except 127.0.0.1 # stunnel already adds the header + + # Those servers want the IP Address in X-Client + backend www + mode http + option forwardfor header X-Client + + See also : "option httpclose", "option http-server-close", + "option http-keep-alive" + + +option h1-case-adjust-bogus-client +no option h1-case-adjust-bogus-client + Enable or disable the case adjustment of HTTP/1 headers sent to bogus clients + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + There is no standard case for header names because, as stated in RFC7230, + they are case-insensitive. So applications must handle them in a case- + insensitive manner. But some bogus applications violate the standards and + erroneously rely on the cases most commonly used by browsers. This problem + becomes critical with HTTP/2 because all header names must be exchanged in + lower case, and HAProxy follows the same convention. All header names are + sent in lower case to clients and servers, regardless of the HTTP version. + + When HAProxy receives an HTTP/1 response, its header names are converted to + lower case and manipulated and sent this way to the clients. If a client is + known to violate the HTTP standards and to fail to process a response coming + from HAProxy, it is possible to transform the lower case header names to a + different format when the response is formatted and sent to the client, by + enabling this option and specifying the list of headers to be reformatted + using the global directives "h1-case-adjust" or "h1-case-adjust-file". This + must only be a temporary workaround for the time it takes the client to be + fixed, because clients which require such workarounds might be vulnerable to + content smuggling attacks and must absolutely be fixed. + + Please note that this option will not affect standards-compliant clients. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also: "option h1-case-adjust-bogus-server", "h1-case-adjust", + "h1-case-adjust-file". + + +option h1-case-adjust-bogus-server +no option h1-case-adjust-bogus-server + Enable or disable the case adjustment of HTTP/1 headers sent to bogus servers + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + There is no standard case for header names because, as stated in RFC7230, + they are case-insensitive. So applications must handle them in a case- + insensitive manner. But some bogus applications violate the standards and + erroneously rely on the cases most commonly used by browsers. This problem + becomes critical with HTTP/2 because all header names must be exchanged in + lower case, and HAProxy follows the same convention. All header names are + sent in lower case to clients and servers, regardless of the HTTP version. + + When HAProxy receives an HTTP/1 request, its header names are converted to + lower case and manipulated and sent this way to the servers. If a server is + known to violate the HTTP standards and to fail to process a request coming + from HAProxy, it is possible to transform the lower case header names to a + different format when the request is formatted and sent to the server, by + enabling this option and specifying the list of headers to be reformatted + using the global directives "h1-case-adjust" or "h1-case-adjust-file". This + must only be a temporary workaround for the time it takes the server to be + fixed, because servers which require such workarounds might be vulnerable to + content smuggling attacks and must absolutely be fixed. + + Please note that this option will not affect standards-compliant servers. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also: "option h1-case-adjust-bogus-client", "h1-case-adjust", + "h1-case-adjust-file". + + +option http-buffer-request +no option http-buffer-request + Enable or disable waiting for whole HTTP request body before proceeding + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + It is sometimes desirable to wait for the body of an HTTP request before + taking a decision. This is what is being done by "balance url_param" for + example. The first use case is to buffer requests from slow clients before + connecting to the server. Another use case consists in taking the routing + decision based on the request body's contents. This option placed in a + frontend or backend forces the HTTP processing to wait until either the whole + body is received or the request buffer is full. It can have undesired side + effects with some applications abusing HTTP by expecting unbuffered + transmissions between the frontend and the backend, so this should definitely + not be used by default. + + See also : "option http-no-delay", "timeout http-request", + "http-request wait-for-body" + + +option http-ignore-probes +no option http-ignore-probes + Enable or disable logging of null connections and request timeouts + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + Recently some browsers started to implement a "pre-connect" feature + consisting in speculatively connecting to some recently visited web sites + just in case the user would like to visit them. This results in many + connections being established to web sites, which end up in 408 Request + Timeout if the timeout strikes first, or 400 Bad Request when the browser + decides to close them first. These ones pollute the log and feed the error + counters. There was already "option dontlognull" but it's insufficient in + this case. Instead, this option does the following things : + - prevent any 400/408 message from being sent to the client if nothing + was received over a connection before it was closed; + - prevent any log from being emitted in this situation; + - prevent any error counter from being incremented + + That way the empty connection is silently ignored. Note that it is better + not to use this unless it is clear that it is needed, because it will hide + real problems. The most common reason for not receiving a request and seeing + a 408 is due to an MTU inconsistency between the client and an intermediary + element such as a VPN, which blocks too large packets. These issues are + generally seen with POST requests as well as GET with large cookies. The logs + are often the only way to detect them. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "log", "dontlognull", "errorfile", and section 8 about logging. + + +option http-keep-alive +no option http-keep-alive + Enable or disable HTTP keep-alive from client to server for HTTP/1.x + connections + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + By default HAProxy operates in keep-alive mode with regards to persistent + HTTP/1.x connections: for each connection it processes each request and + response, and leaves the connection idle on both sides. This mode may be + changed by several options such as "option http-server-close" or "option + httpclose". This option allows to set back the keep-alive mode, which can be + useful when another mode was used in a defaults section. + + Setting "option http-keep-alive" enables HTTP keep-alive mode on the client- + and server- sides. This provides the lowest latency on the client side (slow + network) and the fastest session reuse on the server side at the expense + of maintaining idle connections to the servers. In general, it is possible + with this option to achieve approximately twice the request rate that the + "http-server-close" option achieves on small objects. There are mainly two + situations where this option may be useful : + + - when the server is non-HTTP compliant and authenticates the connection + instead of requests (e.g. NTLM authentication) + + - when the cost of establishing the connection to the server is significant + compared to the cost of retrieving the associated object from the server. + + This last case can happen when the server is a fast static server of cache. + + At the moment, logs will not indicate whether requests came from the same + session or not. The accept date reported in the logs corresponds to the end + of the previous request, and the request time corresponds to the time spent + waiting for a new request. The keep-alive request time is still bound to the + timeout defined by "timeout http-keep-alive" or "timeout http-request" if + not set. + + This option disables and replaces any previous "option httpclose" or "option + http-server-close". + + See also : "option httpclose",, "option http-server-close", + "option prefer-last-server" and "option http-pretend-keepalive". + + +option http-no-delay +no option http-no-delay + Instruct the system to favor low interactive delays over performance in HTTP + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + In HTTP, each payload is unidirectional and has no notion of interactivity. + Any agent is expected to queue data somewhat for a reasonably low delay. + There are some very rare server-to-server applications that abuse the HTTP + protocol and expect the payload phase to be highly interactive, with many + interleaved data chunks in both directions within a single request. This is + absolutely not supported by the HTTP specification and will not work across + most proxies or servers. When such applications attempt to do this through + HAProxy, it works but they will experience high delays due to the network + optimizations which favor performance by instructing the system to wait for + enough data to be available in order to only send full packets. Typical + delays are around 200 ms per round trip. Note that this only happens with + abnormal uses. Normal uses such as CONNECT requests nor WebSockets are not + affected. + + When "option http-no-delay" is present in either the frontend or the backend + used by a connection, all such optimizations will be disabled in order to + make the exchanges as fast as possible. Of course this offers no guarantee on + the functionality, as it may break at any other place. But if it works via + HAProxy, it will work as fast as possible. This option should never be used + by default, and should never be used at all unless such a buggy application + is discovered. The impact of using this option is an increase of bandwidth + usage and CPU usage, which may significantly lower performance in high + latency environments. + + See also : "option http-buffer-request" + + +option http-pretend-keepalive +no option http-pretend-keepalive + Define whether HAProxy will announce keepalive for HTTP/1.x connection to the + server or not + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + When running with "option http-server-close" or "option httpclose", HAProxy + adds a "Connection: close" header to the HTTP/1.x request forwarded to the + server. Unfortunately, when some servers see this header, they automatically + refrain from using the chunked encoding for responses of unknown length, + while this is totally unrelated. The effect is that a client or a cache could + receive an incomplete response without being aware of it, and consider the + response complete. + + By setting "option http-pretend-keepalive", HAProxy will make the server + believe it will keep the connection alive. The server will then not fall back + to the abnormal undesired above. When HAProxy gets the whole response, it + will close the connection with the server just as it would do with the + "option httpclose". That way the client gets a normal response and the + connection is correctly closed on the server side. + + It is recommended not to enable this option by default, because most servers + will more efficiently close the connection themselves after the last packet, + and release its buffers slightly earlier. Also, the added packet on the + network could slightly reduce the overall peak performance. However it is + worth noting that when this option is enabled, HAProxy will have slightly + less work to do. So if HAProxy is the bottleneck on the whole architecture, + enabling this option might save a few CPU cycles. + + This option may be set in backend and listen sections. Using it in a frontend + section will be ignored and a warning will be reported during startup. It is + a backend related option, so there is no real reason to set it on a + frontend. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "option httpclose", "option http-server-close", and + "option http-keep-alive" + +option http-restrict-req-hdr-names { preserve | delete | reject } + Set HAProxy policy about HTTP request header names containing characters + outside the "[a-zA-Z0-9-]" charset + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + preserve disable the filtering. It is the default mode for HTTP proxies + with no FastCGI application configured. + + delete remove request headers with a name containing a character + outside the "[a-zA-Z0-9-]" charset. It is the default mode for + HTTP backends with a configured FastCGI application. + + reject reject the request with a 403-Forbidden response if it contains a + header name with a character outside the "[a-zA-Z0-9-]" charset. + + This option may be used to restrict the request header names to alphanumeric + and hyphen characters ([A-Za-z0-9-]). This may be mandatory to interoperate + with non-HTTP compliant servers that fail to handle some characters in header + names. It may also be mandatory for FastCGI applications because all + non-alphanumeric characters in header names are replaced by an underscore + ('_'). Thus, it is easily possible to mix up header names and bypass some + rules. For instance, "X-Forwarded-For" and "X_Forwarded-For" headers are both + converted to "HTTP_X_FORWARDED_FOR" in FastCGI. + + Note this option is evaluated per proxy and after the http-request rules + evaluation. + +option http-server-close +no option http-server-close + Enable or disable HTTP/1.x connection closing on the server side + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + By default HAProxy operates in keep-alive mode with regards to persistent + HTTP/1.x connections: for each connection it processes each request and + response, and leaves the connection idle on both sides. This mode may be + changed by several options such as "option http-server-close" or "option + httpclose". Setting "option http-server-close" enables HTTP connection-close + mode on the server side while keeping the ability to support HTTP keep-alive + and pipelining on the client side. This provides the lowest latency on the + client side (slow network) and the fastest session reuse on the server side + to save server resources, similarly to "option httpclose". It also permits + non-keepalive capable servers to be served in keep-alive mode to the clients + if they conform to the requirements of RFC7230. Please note that some servers + do not always conform to those requirements when they see "Connection: close" + in the request. The effect will be that keep-alive will never be used. A + workaround consists in enabling "option http-pretend-keepalive". + + At the moment, logs will not indicate whether requests came from the same + session or not. The accept date reported in the logs corresponds to the end + of the previous request, and the request time corresponds to the time spent + waiting for a new request. The keep-alive request time is still bound to the + timeout defined by "timeout http-keep-alive" or "timeout http-request" if + not set. + + This option may be set both in a frontend and in a backend. It is enabled if + at least one of the frontend or backend holding a connection has it enabled. + It disables and replaces any previous "option httpclose" or "option + http-keep-alive". Please check section 4 ("Proxies") to see how this option + combines with others when frontend and backend options differ. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "option httpclose", "option http-pretend-keepalive" and + "option http-keep-alive". + +option http-use-proxy-header +no option http-use-proxy-header + Make use of non-standard Proxy-Connection header instead of Connection + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + While RFC7230 explicitly states that HTTP/1.1 agents must use the + Connection header to indicate their wish of persistent or non-persistent + connections, both browsers and proxies ignore this header for proxied + connections and make use of the undocumented, non-standard Proxy-Connection + header instead. The issue begins when trying to put a load balancer between + browsers and such proxies, because there will be a difference between what + HAProxy understands and what the client and the proxy agree on. + + By setting this option in a frontend, HAProxy can automatically switch to use + that non-standard header if it sees proxied requests. A proxied request is + defined here as one where the URI begins with neither a '/' nor a '*'. This + is incompatible with the HTTP tunnel mode. Note that this option can only be + specified in a frontend and will affect the request along its whole life. + + Also, when this option is set, a request which requires authentication will + automatically switch to use proxy authentication headers if it is itself a + proxied request. That makes it possible to check or enforce authentication in + front of an existing proxy. + + This option should normally never be used, except in front of a proxy. + + See also : "option httpclose", and "option http-server-close". + +option httpchk +option httpchk <uri> +option httpchk <method> <uri> +option httpchk <method> <uri> <version> + Enables HTTP protocol to check on the servers health + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <method> is the optional HTTP method used with the requests. When not set, + the "OPTIONS" method is used, as it generally requires low server + processing and is easy to filter out from the logs. Any method + may be used, though it is not recommended to invent non-standard + ones. + + <uri> is the URI referenced in the HTTP requests. It defaults to " / " + which is accessible by default on almost any server, but may be + changed to any other URI. Query strings are permitted. + + <version> is the optional HTTP version string. It defaults to "HTTP/1.0" + but some servers might behave incorrectly in HTTP 1.0, so turning + it to HTTP/1.1 may sometimes help. Note that the Host field is + mandatory in HTTP/1.1, use "http-check send" directive to add it. + + By default, server health checks only consist in trying to establish a TCP + connection. When "option httpchk" is specified, a complete HTTP request is + sent once the TCP connection is established, and responses 2xx and 3xx are + considered valid, while all other ones indicate a server failure, including + the lack of any response. + + Combined with "http-check" directives, it is possible to customize the + request sent during the HTTP health checks or the matching rules on the + response. It is also possible to configure a send/expect sequence, just like + with the directive "tcp-check" for TCP health checks. + + The server configuration is used by default to open connections to perform + HTTP health checks. By it is also possible to overwrite server parameters + using "http-check connect" rules. + + "httpchk" option does not necessarily require an HTTP backend, it also works + with plain TCP backends. This is particularly useful to check simple scripts + bound to some dedicated ports using the inetd daemon. However, it will always + internally relies on an HTX multiplexer. Thus, it means the request + formatting and the response parsing will be strict. + + Note : For a while, there was no way to add headers or body in the request + used for HTTP health checks. So a workaround was to hide it at the end + of the version string with a "\r\n" after the version. It is now + deprecated. The directive "http-check send" must be used instead. + + Examples : + # Relay HTTPS traffic to Apache instance and check service availability + # using HTTP request "OPTIONS * HTTP/1.1" on port 80. + backend https_relay + mode tcp + option httpchk OPTIONS * HTTP/1.1 + http-check send hdr Host www + server apache1 192.168.1.1:443 check port 80 + + See also : "option ssl-hello-chk", "option smtpchk", "option mysql-check", + "option pgsql-check", "http-check" and the "check", "port" and + "inter" server options. + + +option httpclose +no option httpclose + Enable or disable HTTP/1.x connection closing + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + By default HAProxy operates in keep-alive mode with regards to persistent + HTTP/1.x connections: for each connection it processes each request and + response, and leaves the connection idle on both sides. This mode may be + changed by several options such as "option http-server-close" or "option + httpclose". + + If "option httpclose" is set, HAProxy will close the client or the server + connection, depending where the option is set. Only the frontend is + considered for client connections while the frontend and the backend are + considered for server ones. In this case the option is enabled if at least + one of the frontend or backend holding the connection has it enabled. If the + option is set on a listener, it is applied both on client and server + connections. It will check if a "Connection: close" header is already set in + each direction, and will add one if missing. + + This option may also be combined with "option http-pretend-keepalive", which + will disable sending of the "Connection: close" request header, but will + still cause the connection to be closed once the whole response is received. + + It disables and replaces any previous "option http-server-close" or "option + http-keep-alive". + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "option http-server-close". + + +option httplog [ clf ] + Enable logging of HTTP request, session state and timers + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : + clf if the "clf" argument is added, then the output format will be + the CLF format instead of HAProxy's default HTTP format. You can + use this when you need to feed HAProxy's logs through a specific + log analyzer which only support the CLF format and which is not + extensible. + + By default, the log output format is very poor, as it only contains the + source and destination addresses, and the instance name. By specifying + "option httplog", each log line turns into a much richer format including, + but not limited to, the HTTP request, the connection timers, the session + status, the connections numbers, the captured headers and cookies, the + frontend, backend and server name, and of course the source address and + ports. + + Specifying only "option httplog" will automatically clear the 'clf' mode + if it was set by default. + + "option httplog" overrides any previous "log-format" directive. + + See also : section 8 about logging. + +option httpslog + Enable logging of HTTPS request, session state and timers + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + + By default, the log output format is very poor, as it only contains the + source and destination addresses, and the instance name. By specifying + "option httpslog", each log line turns into a much richer format including, + but not limited to, the HTTP request, the connection timers, the session + status, the connections numbers, the captured headers and cookies, the + frontend, backend and server name, the SSL certificate verification and SSL + handshake statuses, and of course the source address and ports. + + "option httpslog" overrides any previous "log-format" directive. + + See also : section 8 about logging. + + +option independent-streams +no option independent-streams + Enable or disable independent timeout processing for both directions + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + By default, when data is sent over a socket, both the write timeout and the + read timeout for that socket are refreshed, because we consider that there is + activity on that socket, and we have no other means of guessing if we should + receive data or not. + + While this default behavior is desirable for almost all applications, there + exists a situation where it is desirable to disable it, and only refresh the + read timeout if there are incoming data. This happens on sessions with large + timeouts and low amounts of exchanged data such as telnet session. If the + server suddenly disappears, the output data accumulates in the system's + socket buffers, both timeouts are correctly refreshed, and there is no way + to know the server does not receive them, so we don't timeout. However, when + the underlying protocol always echoes sent data, it would be enough by itself + to detect the issue using the read timeout. Note that this problem does not + happen with more verbose protocols because data won't accumulate long in the + socket buffers. + + When this option is set on the frontend, it will disable read timeout updates + on data sent to the client. There probably is little use of this case. When + the option is set on the backend, it will disable read timeout updates on + data sent to the server. Doing so will typically break large HTTP posts from + slow lines, so use it with caution. + + See also : "timeout client", "timeout server" and "timeout tunnel" + + +option ldap-check + Use LDAPv3 health checks for server testing + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + It is possible to test that the server correctly talks LDAPv3 instead of just + testing that it accepts the TCP connection. When this option is set, an + LDAPv3 anonymous simple bind message is sent to the server, and the response + is analyzed to find an LDAPv3 bind response message. + + The server is considered valid only when the LDAP response contains success + resultCode (http://tools.ietf.org/html/rfc4511#section-4.1.9). + + Logging of bind requests is server dependent see your documentation how to + configure it. + + Example : + option ldap-check + + See also : "option httpchk" + + +option external-check + Use external processes for server health checks + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + + It is possible to test the health of a server using an external command. + This is achieved by running the executable set using "external-check + command". + + Requires the "external-check" global to be set. + + See also : "external-check", "external-check command", "external-check path" + + +option idle-close-on-response +no option idle-close-on-response + Avoid closing idle frontend connections if a soft stop is in progress + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + By default, idle connections will be closed during a soft stop. In some + environments, a client talking to the proxy may have prepared some idle + connections in order to send requests later. If there is no proper retry on + write errors, this can result in errors while haproxy is reloading. Even + though a proper implementation should retry on connection/write errors, this + option was introduced to support backwards compatibility with haproxy prior + to version 2.4. Indeed before v2.4, haproxy used to wait for a last request + and response to add a "connection: close" header before closing, thus + notifying the client that the connection would not be reusable. + + In a real life example, this behavior was seen in AWS using the ALB in front + of a haproxy. The end result was ALB sending 502 during haproxy reloads. + + Users are warned that using this option may increase the number of old + processes if connections remain idle for too long. Adjusting the client + timeouts and/or the "hard-stop-after" parameter accordingly might be + needed in case of frequent reloads. + + See also: "timeout client", "timeout client-fin", "timeout http-request", + "hard-stop-after" + + +option log-health-checks +no option log-health-checks + Enable or disable logging of health checks status updates + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + By default, failed health check are logged if server is UP and successful + health checks are logged if server is DOWN, so the amount of additional + information is limited. + + When this option is enabled, any change of the health check status or to + the server's health will be logged, so that it becomes possible to know + that a server was failing occasional checks before crashing, or exactly when + it failed to respond a valid HTTP status, then when the port started to + reject connections, then when the server stopped responding at all. + + Note that status changes not caused by health checks (e.g. enable/disable on + the CLI) are intentionally not logged by this option. + + See also: "option httpchk", "option ldap-check", "option mysql-check", + "option pgsql-check", "option redis-check", "option smtpchk", + "option tcp-check", "log" and section 8 about logging. + + +option log-separate-errors +no option log-separate-errors + Change log level for non-completely successful connections + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + Sometimes looking for errors in logs is not easy. This option makes HAProxy + raise the level of logs containing potentially interesting information such + as errors, timeouts, retries, redispatches, or HTTP status codes 5xx. The + level changes from "info" to "err". This makes it possible to log them + separately to a different file with most syslog daemons. Be careful not to + remove them from the original file, otherwise you would lose ordering which + provides very important information. + + Using this option, large sites dealing with several thousand connections per + second may log normal traffic to a rotating buffer and only archive smaller + error logs. + + See also : "log", "dontlognull", "dontlog-normal" and section 8 about + logging. + + +option logasap +no option logasap + Enable or disable early logging. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + By default, logs are emitted when all the log format variables and sample + fetches used in the definition of the log-format string return a value, or + when the session is terminated. This allows the built in log-format strings + to account for the transfer time, or the number of bytes in log messages. + + When handling long lived connections such as large file transfers or RDP, + it may take a while for the request or connection to appear in the logs. + Using "option logasap", the log message is created as soon as the server + connection is established in mode tcp, or as soon as the server sends the + complete headers in mode http. Missing information in the logs will be the + total number of bytes which will only indicate the amount of data transferred + before the message was created and the total time which will not take the + remainder of the connection life or transfer time into account. For the case + of HTTP, it is good practice to capture the Content-Length response header + so that the logs at least indicate how many bytes are expected to be + transferred. + + Examples : + listen http_proxy 0.0.0.0:80 + mode http + option httplog + option logasap + log 192.168.2.200 local3 + + >>> Feb 6 12:14:14 localhost \ + haproxy[14389]: 10.0.1.2:33317 [06/Feb/2009:12:14:14.655] http-in \ + static/srv1 9/10/7/14/+30 200 +243 - - ---- 3/1/1/1/0 1/0 \ + "GET /image.iso HTTP/1.0" + + See also : "option httplog", "capture response header", and section 8 about + logging. + + +option mysql-check [ user <username> [ { post-41 | pre-41 } ] ] + Use MySQL health checks for server testing + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <username> This is the username which will be used when connecting to MySQL + server. + post-41 Send post v4.1 client compatible checks (the default) + pre-41 Send pre v4.1 client compatible checks + + If you specify a username, the check consists of sending two MySQL packet, + one Client Authentication packet, and one QUIT packet, to correctly close + MySQL session. We then parse the MySQL Handshake Initialization packet and/or + Error packet. It is a basic but useful test which does not produce error nor + aborted connect on the server. However, it requires an unlocked authorised + user without a password. To create a basic limited user in MySQL with + optional resource limits: + + CREATE USER '<username>'@'<ip_of_haproxy|network_of_haproxy/netmask>' + /*!50701 WITH MAX_QUERIES_PER_HOUR 1 MAX_UPDATES_PER_HOUR 0 */ + /*M!100201 MAX_STATEMENT_TIME 0.0001 */; + + If you don't specify a username (it is deprecated and not recommended), the + check only consists in parsing the Mysql Handshake Initialization packet or + Error packet, we don't send anything in this mode. It was reported that it + can generate lockout if check is too frequent and/or if there is not enough + traffic. In fact, you need in this case to check MySQL "max_connect_errors" + value as if a connection is established successfully within fewer than MySQL + "max_connect_errors" attempts after a previous connection was interrupted, + the error count for the host is cleared to zero. If HAProxy's server get + blocked, the "FLUSH HOSTS" statement is the only way to unblock it. + + Remember that this does not check database presence nor database consistency. + To do this, you can use an external check with xinetd for example. + + The check requires MySQL >=3.22, for older version, please use TCP check. + + Most often, an incoming MySQL server needs to see the client's IP address for + various purposes, including IP privilege matching and connection logging. + When possible, it is often wise to masquerade the client's IP address when + connecting to the server using the "usesrc" argument of the "source" keyword, + which requires the transparent proxy feature to be compiled in, and the MySQL + server to route the client via the machine hosting HAProxy. + + See also: "option httpchk" + + +option nolinger +no option nolinger + Enable or disable immediate session resource cleaning after close + May be used in sections: defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + When clients or servers abort connections in a dirty way (e.g. they are + physically disconnected), the session timeouts triggers and the session is + closed. But it will remain in FIN_WAIT1 state for some time in the system, + using some resources and possibly limiting the ability to establish newer + connections. + + When this happens, it is possible to activate "option nolinger" which forces + the system to immediately remove any socket's pending data on close. Thus, + a TCP RST is emitted, any pending data are truncated, and the session is + instantly purged from the system's tables. The generally visible effect for + a client is that responses are truncated if the close happens with a last + block of data (e.g. on a redirect or error response). On the server side, + it may help release the source ports immediately when forwarding a client + aborts in tunnels. In both cases, TCP resets are emitted and given that + the session is instantly destroyed, there will be no retransmit. On a lossy + network this can increase problems, especially when there is a firewall on + the lossy side, because the firewall might see and process the reset (hence + purge its session) and block any further traffic for this session,, including + retransmits from the other side. So if the other side doesn't receive it, + it will never receive any RST again, and the firewall might log many blocked + packets. + + For all these reasons, it is strongly recommended NOT to use this option, + unless absolutely needed as a last resort. In most situations, using the + "client-fin" or "server-fin" timeouts achieves similar results with a more + reliable behavior. On Linux it's also possible to use the "tcp-ut" bind or + server setting. + + This option may be used both on frontends and backends, depending on the side + where it is required. Use it on the frontend for clients, and on the backend + for servers. While this option is technically supported in "defaults" + sections, it must really not be used there as it risks to accidentally + propagate to sections that must no use it and to cause problems there. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also: "timeout client-fin", "timeout server-fin", "tcp-ut" bind or server + keywords. + +option originalto [ except <network> ] [ header <name> ] + Enable insertion of the X-Original-To header to requests sent to servers + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <network> is an optional argument used to disable this option for sources + matching <network> + <name> an optional argument to specify a different "X-Original-To" + header name. + + Since HAProxy can work in transparent mode, every request from a client can + be redirected to the proxy and HAProxy itself can proxy every request to a + complex SQUID environment and the destination host from SO_ORIGINAL_DST will + be lost. This is annoying when you want access rules based on destination ip + addresses. To solve this problem, a new HTTP header "X-Original-To" may be + added by HAProxy to all requests sent to the server. This header contains a + value representing the original destination IP address. Since this must be + configured to always use the last occurrence of this header only. Note that + only the last occurrence of the header must be used, since it is really + possible that the client has already brought one. + + The keyword "header" may be used to supply a different header name to replace + the default "X-Original-To". This can be useful where you might already + have a "X-Original-To" header from a different application, and you need + preserve it. Also if your backend server doesn't use the "X-Original-To" + header and requires different one. + + Sometimes, a same HAProxy instance may be shared between a direct client + access and a reverse-proxy access (for instance when an SSL reverse-proxy is + used to decrypt HTTPS traffic). It is possible to disable the addition of the + header for a known destination address or network by adding the "except" + keyword followed by the network address. In this case, any destination IP + matching the network will not cause an addition of this header. Most common + uses are with private networks or 127.0.0.1. IPv4 and IPv6 are both + supported. + + This option may be specified either in the frontend or in the backend. If at + least one of them uses it, the header will be added. Note that the backend's + setting of the header subargument takes precedence over the frontend's if + both are defined. + + Examples : + # Original Destination address + frontend www + mode http + option originalto except 127.0.0.1 + + # Those servers want the IP Address in X-Client-Dst + backend www + mode http + option originalto header X-Client-Dst + + See also : "option httpclose", "option http-server-close". + + +option persist +no option persist + Enable or disable forced persistence on down servers + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + When an HTTP request reaches a backend with a cookie which references a dead + server, by default it is redispatched to another server. It is possible to + force the request to be sent to the dead server first using "option persist" + if absolutely needed. A common use case is when servers are under extreme + load and spend their time flapping. In this case, the users would still be + directed to the server they opened the session on, in the hope they would be + correctly served. It is recommended to use "option redispatch" in conjunction + with this option so that in the event it would not be possible to connect to + the server at all (server definitely dead), the client would finally be + redirected to another valid server. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "option redispatch", "retries", "force-persist" + + +option pgsql-check user <username> + Use PostgreSQL health checks for server testing + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <username> This is the username which will be used when connecting to + PostgreSQL server. + + The check sends a PostgreSQL StartupMessage and waits for either + Authentication request or ErrorResponse message. It is a basic but useful + test which does not produce error nor aborted connect on the server. + This check is identical with the "mysql-check". + + See also: "option httpchk" + + +option prefer-last-server +no option prefer-last-server + Allow multiple load balanced requests to remain on the same server + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + When the load balancing algorithm in use is not deterministic, and a previous + request was sent to a server to which HAProxy still holds a connection, it is + sometimes desirable that subsequent requests on a same session go to the same + server as much as possible. Note that this is different from persistence, as + we only indicate a preference which HAProxy tries to apply without any form + of warranty. The real use is for keep-alive connections sent to servers. When + this option is used, HAProxy will try to reuse the same connection that is + attached to the server instead of rebalancing to another server, causing a + close of the connection. This can make sense for static file servers. It does + not make much sense to use this in combination with hashing algorithms. Note, + HAProxy already automatically tries to stick to a server which sends a 401 or + to a proxy which sends a 407 (authentication required), when the load + balancing algorithm is not deterministic. This is mandatory for use with the + broken NTLM authentication challenge, and significantly helps in + troubleshooting some faulty applications. Option prefer-last-server might be + desirable in these environments as well, to avoid redistributing the traffic + after every other response. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also: "option http-keep-alive" + + +option redispatch +option redispatch <interval> +no option redispatch + Enable or disable session redistribution in case of connection failure + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <interval> The optional integer value that controls how often redispatches + occur when retrying connections. Positive value P indicates a + redispatch is desired on every Pth retry, and negative value + N indicate a redispatch is desired on the Nth retry prior to the + last retry. For example, the default of -1 preserves the + historical behavior of redispatching on the last retry, a + positive value of 1 would indicate a redispatch on every retry, + and a positive value of 3 would indicate a redispatch on every + third retry. You can disable redispatches with a value of 0. + + + In HTTP mode, if a server designated by a cookie is down, clients may + definitely stick to it because they cannot flush the cookie, so they will not + be able to access the service anymore. + + Specifying "option redispatch" will allow the proxy to break cookie or + consistent hash based persistence and redistribute them to a working server. + + Active servers are selected from a subset of the list of available + servers. Active servers that are not down or in maintenance (i.e., whose + health is not checked or that have been checked as "up"), are selected in the + following order: + + 1. Any active, non-backup server, if any, or, + + 2. If the "allbackups" option is not set, the first backup server in the + list, or + + 3. If the "allbackups" option is set, any backup server. + + When a retry occurs, HAProxy tries to select another server than the last + one. The new server is selected from the current list of servers. + + Sometimes, if the list is updated between retries (e.g., if numerous retries + occur and last longer than the time needed to check that a server is down, + remove it from the list and fall back on the list of backup servers), + connections may be redirected to a backup server, though. + + It also allows to retry connections to another server in case of multiple + connection failures. Of course, it requires having "retries" set to a nonzero + value. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "retries", "force-persist" + + +option redis-check + Use redis health checks for server testing + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + It is possible to test that the server correctly talks REDIS protocol instead + of just testing that it accepts the TCP connection. When this option is set, + a PING redis command is sent to the server, and the response is analyzed to + find the "+PONG" response message. + + Example : + option redis-check + + See also : "option httpchk", "option tcp-check", "tcp-check expect" + + +option smtpchk +option smtpchk <hello> <domain> + Use SMTP health checks for server testing + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <hello> is an optional argument. It is the "hello" command to use. It can + be either "HELO" (for SMTP) or "EHLO" (for ESMTP). All other + values will be turned into the default command ("HELO"). + + <domain> is the domain name to present to the server. It may only be + specified (and is mandatory) if the hello command has been + specified. By default, "localhost" is used. + + When "option smtpchk" is set, the health checks will consist in TCP + connections followed by an SMTP command. By default, this command is + "HELO localhost". The server's return code is analyzed and only return codes + starting with a "2" will be considered as valid. All other responses, + including a lack of response will constitute an error and will indicate a + dead server. + + This test is meant to be used with SMTP servers or relays. Depending on the + request, it is possible that some servers do not log each connection attempt, + so you may want to experiment to improve the behavior. Using telnet on port + 25 is often easier than adjusting the configuration. + + Most often, an incoming SMTP server needs to see the client's IP address for + various purposes, including spam filtering, anti-spoofing and logging. When + possible, it is often wise to masquerade the client's IP address when + connecting to the server using the "usesrc" argument of the "source" keyword, + which requires the transparent proxy feature to be compiled in. + + Example : + option smtpchk HELO mydomain.org + + See also : "option httpchk", "source" + + +option socket-stats +no option socket-stats + + Enable or disable collecting & providing separate statistics for each socket. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + + Arguments : none + + +option splice-auto +no option splice-auto + Enable or disable automatic kernel acceleration on sockets in both directions + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + When this option is enabled either on a frontend or on a backend, HAProxy + will automatically evaluate the opportunity to use kernel tcp splicing to + forward data between the client and the server, in either direction. HAProxy + uses heuristics to estimate if kernel splicing might improve performance or + not. Both directions are handled independently. Note that the heuristics used + are not much aggressive in order to limit excessive use of splicing. This + option requires splicing to be enabled at compile time, and may be globally + disabled with the global option "nosplice". Since splice uses pipes, using it + requires that there are enough spare pipes. + + Important note: kernel-based TCP splicing is a Linux-specific feature which + first appeared in kernel 2.6.25. It offers kernel-based acceleration to + transfer data between sockets without copying these data to user-space, thus + providing noticeable performance gains and CPU cycles savings. Since many + early implementations are buggy, corrupt data and/or are inefficient, this + feature is not enabled by default, and it should be used with extreme care. + While it is not possible to detect the correctness of an implementation, + 2.6.29 is the first version offering a properly working implementation. In + case of doubt, splicing may be globally disabled using the global "nosplice" + keyword. + + Example : + option splice-auto + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "option splice-request", "option splice-response", and global + options "nosplice" and "maxpipes" + + +option splice-request +no option splice-request + Enable or disable automatic kernel acceleration on sockets for requests + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + When this option is enabled either on a frontend or on a backend, HAProxy + will use kernel tcp splicing whenever possible to forward data going from + the client to the server. It might still use the recv/send scheme if there + are no spare pipes left. This option requires splicing to be enabled at + compile time, and may be globally disabled with the global option "nosplice". + Since splice uses pipes, using it requires that there are enough spare pipes. + + Important note: see "option splice-auto" for usage limitations. + + Example : + option splice-request + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "option splice-auto", "option splice-response", and global options + "nosplice" and "maxpipes" + + +option splice-response +no option splice-response + Enable or disable automatic kernel acceleration on sockets for responses + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + When this option is enabled either on a frontend or on a backend, HAProxy + will use kernel tcp splicing whenever possible to forward data going from + the server to the client. It might still use the recv/send scheme if there + are no spare pipes left. This option requires splicing to be enabled at + compile time, and may be globally disabled with the global option "nosplice". + Since splice uses pipes, using it requires that there are enough spare pipes. + + Important note: see "option splice-auto" for usage limitations. + + Example : + option splice-response + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "option splice-auto", "option splice-request", and global options + "nosplice" and "maxpipes" + + +option spop-check + Use SPOP health checks for server testing + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + It is possible to test that the server correctly talks SPOP protocol instead + of just testing that it accepts the TCP connection. When this option is set, + a HELLO handshake is performed between HAProxy and the server, and the + response is analyzed to check no error is reported. + + Example : + option spop-check + + See also : "option httpchk" + + +option srvtcpka +no option srvtcpka + Enable or disable the sending of TCP keepalive packets on the server side + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + When there is a firewall or any session-aware component between a client and + a server, and when the protocol involves very long sessions with long idle + periods (e.g. remote desktops), there is a risk that one of the intermediate + components decides to expire a session which has remained idle for too long. + + Enabling socket-level TCP keep-alives makes the system regularly send packets + to the other end of the connection, leaving it active. The delay between + keep-alive probes is controlled by the system only and depends both on the + operating system and its tuning parameters. + + It is important to understand that keep-alive packets are neither emitted nor + received at the application level. It is only the network stacks which sees + them. For this reason, even if one side of the proxy already uses keep-alives + to maintain its connection alive, those keep-alive packets will not be + forwarded to the other side of the proxy. + + Please note that this has nothing to do with HTTP keep-alive. + + Using option "srvtcpka" enables the emission of TCP keep-alive probes on the + server side of a connection, which should help when session expirations are + noticed between HAProxy and a server. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "option clitcpka", "option tcpka" + + +option ssl-hello-chk + Use SSLv3 client hello health checks for server testing + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + When some SSL-based protocols are relayed in TCP mode through HAProxy, it is + possible to test that the server correctly talks SSL instead of just testing + that it accepts the TCP connection. When "option ssl-hello-chk" is set, pure + SSLv3 client hello messages are sent once the connection is established to + the server, and the response is analyzed to find an SSL server hello message. + The server is considered valid only when the response contains this server + hello message. + + All servers tested till there correctly reply to SSLv3 client hello messages, + and most servers tested do not even log the requests containing only hello + messages, which is appreciable. + + Note that this check works even when SSL support was not built into HAProxy + because it forges the SSL message. When SSL support is available, it is best + to use native SSL health checks instead of this one. + + See also: "option httpchk", "check-ssl" + + +option tcp-check + Perform health checks using tcp-check send/expect sequences + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + + This health check method is intended to be combined with "tcp-check" command + lists in order to support send/expect types of health check sequences. + + TCP checks currently support 4 modes of operations : + - no "tcp-check" directive : the health check only consists in a connection + attempt, which remains the default mode. + + - "tcp-check send" or "tcp-check send-binary" only is mentioned : this is + used to send a string along with a connection opening. With some + protocols, it helps sending a "QUIT" message for example that prevents + the server from logging a connection error for each health check. The + check result will still be based on the ability to open the connection + only. + + - "tcp-check expect" only is mentioned : this is used to test a banner. + The connection is opened and HAProxy waits for the server to present some + contents which must validate some rules. The check result will be based + on the matching between the contents and the rules. This is suited for + POP, IMAP, SMTP, FTP, SSH, TELNET. + + - both "tcp-check send" and "tcp-check expect" are mentioned : this is + used to test a hello-type protocol. HAProxy sends a message, the server + responds and its response is analyzed. the check result will be based on + the matching between the response contents and the rules. This is often + suited for protocols which require a binding or a request/response model. + LDAP, MySQL, Redis and SSL are example of such protocols, though they + already all have their dedicated checks with a deeper understanding of + the respective protocols. + In this mode, many questions may be sent and many answers may be + analyzed. + + A fifth mode can be used to insert comments in different steps of the script. + + For each tcp-check rule you create, you can add a "comment" directive, + followed by a string. This string will be reported in the log and stderr in + debug mode. It is useful to make user-friendly error reporting. The + "comment" is of course optional. + + During the execution of a health check, a variable scope is made available to + store data samples, using the "tcp-check set-var" operation. Freeing those + variable is possible using "tcp-check unset-var". + + + Examples : + # perform a POP check (analyze only server's banner) + option tcp-check + tcp-check expect string +OK\ POP3\ ready comment POP\ protocol + + # perform an IMAP check (analyze only server's banner) + option tcp-check + tcp-check expect string *\ OK\ IMAP4\ ready comment IMAP\ protocol + + # look for the redis master server after ensuring it speaks well + # redis protocol, then it exits properly. + # (send a command then analyze the response 3 times) + option tcp-check + tcp-check comment PING\ phase + tcp-check send PING\r\n + tcp-check expect string +PONG + tcp-check comment role\ check + tcp-check send info\ replication\r\n + tcp-check expect string role:master + tcp-check comment QUIT\ phase + tcp-check send QUIT\r\n + tcp-check expect string +OK + + forge a HTTP request, then analyze the response + (send many headers before analyzing) + option tcp-check + tcp-check comment forge\ and\ send\ HTTP\ request + tcp-check send HEAD\ /\ HTTP/1.1\r\n + tcp-check send Host:\ www.mydomain.com\r\n + tcp-check send User-Agent:\ HAProxy\ tcpcheck\r\n + tcp-check send \r\n + tcp-check expect rstring HTTP/1\..\ (2..|3..) comment check\ HTTP\ response + + + See also : "tcp-check connect", "tcp-check expect" and "tcp-check send". + + +option tcp-smart-accept +no option tcp-smart-accept + Enable or disable the saving of one ACK packet during the accept sequence + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + When an HTTP connection request comes in, the system acknowledges it on + behalf of HAProxy, then the client immediately sends its request, and the + system acknowledges it too while it is notifying HAProxy about the new + connection. HAProxy then reads the request and responds. This means that we + have one TCP ACK sent by the system for nothing, because the request could + very well be acknowledged by HAProxy when it sends its response. + + For this reason, in HTTP mode, HAProxy automatically asks the system to avoid + sending this useless ACK on platforms which support it (currently at least + Linux). It must not cause any problem, because the system will send it anyway + after 40 ms if the response takes more time than expected to come. + + During complex network debugging sessions, it may be desirable to disable + this optimization because delayed ACKs can make troubleshooting more complex + when trying to identify where packets are delayed. It is then possible to + fall back to normal behavior by specifying "no option tcp-smart-accept". + + It is also possible to force it for non-HTTP proxies by simply specifying + "option tcp-smart-accept". For instance, it can make sense with some services + such as SMTP where the server speaks first. + + It is recommended to avoid forcing this option in a defaults section. In case + of doubt, consider setting it back to automatic values by prepending the + "default" keyword before it, or disabling it using the "no" keyword. + + See also : "option tcp-smart-connect" + + +option tcp-smart-connect +no option tcp-smart-connect + Enable or disable the saving of one ACK packet during the connect sequence + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + On certain systems (at least Linux), HAProxy can ask the kernel not to + immediately send an empty ACK upon a connection request, but to directly + send the buffer request instead. This saves one packet on the network and + thus boosts performance. It can also be useful for some servers, because they + immediately get the request along with the incoming connection. + + This feature is enabled when "option tcp-smart-connect" is set in a backend. + It is not enabled by default because it makes network troubleshooting more + complex. + + It only makes sense to enable it with protocols where the client speaks first + such as HTTP. In other situations, if there is no data to send in place of + the ACK, a normal ACK is sent. + + If this option has been enabled in a "defaults" section, it can be disabled + in a specific instance by prepending the "no" keyword before it. + + See also : "option tcp-smart-accept" + + +option tcpka + Enable or disable the sending of TCP keepalive packets on both sides + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + When there is a firewall or any session-aware component between a client and + a server, and when the protocol involves very long sessions with long idle + periods (e.g. remote desktops), there is a risk that one of the intermediate + components decides to expire a session which has remained idle for too long. + + Enabling socket-level TCP keep-alives makes the system regularly send packets + to the other end of the connection, leaving it active. The delay between + keep-alive probes is controlled by the system only and depends both on the + operating system and its tuning parameters. + + It is important to understand that keep-alive packets are neither emitted nor + received at the application level. It is only the network stacks which sees + them. For this reason, even if one side of the proxy already uses keep-alives + to maintain its connection alive, those keep-alive packets will not be + forwarded to the other side of the proxy. + + Please note that this has nothing to do with HTTP keep-alive. + + Using option "tcpka" enables the emission of TCP keep-alive probes on both + the client and server sides of a connection. Note that this is meaningful + only in "defaults" or "listen" sections. If this option is used in a + frontend, only the client side will get keep-alives, and if this option is + used in a backend, only the server side will get keep-alives. For this + reason, it is strongly recommended to explicitly use "option clitcpka" and + "option srvtcpka" when the configuration is split between frontends and + backends. + + See also : "option clitcpka", "option srvtcpka" + + +option tcplog + Enable advanced logging of TCP connections with session state and timers + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : none + + By default, the log output format is very poor, as it only contains the + source and destination addresses, and the instance name. By specifying + "option tcplog", each log line turns into a much richer format including, but + not limited to, the connection timers, the session status, the connections + numbers, the frontend, backend and server name, and of course the source + address and ports. This option is useful for pure TCP proxies in order to + find which of the client or server disconnects or times out. For normal HTTP + proxies, it's better to use "option httplog" which is even more complete. + + "option tcplog" overrides any previous "log-format" directive. + + See also : "option httplog", and section 8 about logging. + + +option transparent +no option transparent + Enable client-side transparent proxying + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + This option was introduced in order to provide layer 7 persistence to layer 3 + load balancers. The idea is to use the OS's ability to redirect an incoming + connection for a remote address to a local process (here HAProxy), and let + this process know what address was initially requested. When this option is + used, sessions without cookies will be forwarded to the original destination + IP address of the incoming request (which should match that of another + equipment), while requests with cookies will still be forwarded to the + appropriate server. + + Note that contrary to a common belief, this option does NOT make HAProxy + present the client's IP to the server when establishing the connection. + + See also: the "usesrc" argument of the "source" keyword, and the + "transparent" option of the "bind" keyword. + + +external-check command <command> + Executable to run when performing an external-check + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + <command> is the external command to run + + The arguments passed to the to the command are: + + <proxy_address> <proxy_port> <server_address> <server_port> + + The <proxy_address> and <proxy_port> are derived from the first listener + that is either IPv4, IPv6 or a UNIX socket. In the case of a UNIX socket + listener the proxy_address will be the path of the socket and the + <proxy_port> will be the string "NOT_USED". In a backend section, it's not + possible to determine a listener, and both <proxy_address> and <proxy_port> + will have the string value "NOT_USED". + + Some values are also provided through environment variables. + + Environment variables : + HAPROXY_PROXY_ADDR The first bind address if available (or empty if not + applicable, for example in a "backend" section). + + HAPROXY_PROXY_ID The backend id. + + HAPROXY_PROXY_NAME The backend name. + + HAPROXY_PROXY_PORT The first bind port if available (or empty if not + applicable, for example in a "backend" section or + for a UNIX socket). + + HAPROXY_SERVER_ADDR The server address. + + HAPROXY_SERVER_CURCONN The current number of connections on the server. + + HAPROXY_SERVER_ID The server id. + + HAPROXY_SERVER_MAXCONN The server max connections. + + HAPROXY_SERVER_NAME The server name. + + HAPROXY_SERVER_PORT The server port if available (or empty for a UNIX + socket). + + HAPROXY_SERVER_SSL "0" when SSL is not used, "1" when it is used + + HAPROXY_SERVER_PROTO The protocol used by this server, which can be one + of "cli" (the haproxy CLI), "syslog" (syslog TCP + server), "peers" (peers TCP server), "h1" (HTTP/1.x + server), "h2" (HTTP/2 server), or "tcp" (any other + TCP server). + + PATH The PATH environment variable used when executing + the command may be set using "external-check path". + + See also "2.3. Environment variables" for other variables. + + If the command executed and exits with a zero status then the check is + considered to have passed, otherwise the check is considered to have + failed. + + Example : + external-check command /bin/true + + See also : "external-check", "option external-check", "external-check path" + + +external-check path <path> + The value of the PATH environment variable used when running an external-check + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + <path> is the path used when executing external command to run + + The default path is "". + + Example : + external-check path "/usr/bin:/bin" + + See also : "external-check", "option external-check", + "external-check command" + + +persist rdp-cookie +persist rdp-cookie(<name>) + Enable RDP cookie-based persistence + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <name> is the optional name of the RDP cookie to check. If omitted, the + default cookie name "msts" will be used. There currently is no + valid reason to change this name. + + This statement enables persistence based on an RDP cookie. The RDP cookie + contains all information required to find the server in the list of known + servers. So when this option is set in the backend, the request is analyzed + and if an RDP cookie is found, it is decoded. If it matches a known server + which is still UP (or if "option persist" is set), then the connection is + forwarded to this server. + + Note that this only makes sense in a TCP backend, but for this to work, the + frontend must have waited long enough to ensure that an RDP cookie is present + in the request buffer. This is the same requirement as with the "rdp-cookie" + load-balancing method. Thus it is highly recommended to put all statements in + a single "listen" section. + + Also, it is important to understand that the terminal server will emit this + RDP cookie only if it is configured for "token redirection mode", which means + that the "IP address redirection" option is disabled. + + Example : + listen tse-farm + bind :3389 + # wait up to 5s for an RDP cookie in the request + tcp-request inspect-delay 5s + tcp-request content accept if RDP_COOKIE + # apply RDP cookie persistence + persist rdp-cookie + # if server is unknown, let's balance on the same cookie. + # alternatively, "balance leastconn" may be useful too. + balance rdp-cookie + server srv1 1.1.1.1:3389 + server srv2 1.1.1.2:3389 + + See also : "balance rdp-cookie", "tcp-request" and the "req.rdp_cookie" ACL. + + +rate-limit sessions <rate> + Set a limit on the number of new sessions accepted per second on a frontend + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : + <rate> The <rate> parameter is an integer designating the maximum number + of new sessions per second to accept on the frontend. + + When the frontend reaches the specified number of new sessions per second, it + stops accepting new connections until the rate drops below the limit again. + During this time, the pending sessions will be kept in the socket's backlog + (in system buffers) and HAProxy will not even be aware that sessions are + pending. When applying very low limit on a highly loaded service, it may make + sense to increase the socket's backlog using the "backlog" keyword. + + This feature is particularly efficient at blocking connection-based attacks + or service abuse on fragile servers. Since the session rate is measured every + millisecond, it is extremely accurate. Also, the limit applies immediately, + no delay is needed at all to detect the threshold. + + Example : limit the connection rate on SMTP to 10 per second max + listen smtp + mode tcp + bind :25 + rate-limit sessions 10 + server smtp1 127.0.0.1:1025 + + Note : when the maximum rate is reached, the frontend's status is not changed + but its sockets appear as "WAITING" in the statistics if the + "socket-stats" option is enabled. + + See also : the "backlog" keyword and the "fe_sess_rate" ACL criterion. + + +redirect location <loc> [code <code>] <option> [{if | unless} <condition>] +redirect prefix <pfx> [code <code>] <option> [{if | unless} <condition>] +redirect scheme <sch> [code <code>] <option> [{if | unless} <condition>] + Return an HTTP redirection if/unless a condition is matched + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | yes + + If/unless the condition is matched, the HTTP request will lead to a redirect + response. If no condition is specified, the redirect applies unconditionally. + + Arguments : + <loc> With "redirect location", the exact value in <loc> is placed into + the HTTP "Location" header. When used in an "http-request" rule, + <loc> value follows the log-format rules and can include some + dynamic values (see Custom Log Format in section 8.2.4). + + <pfx> With "redirect prefix", the "Location" header is built from the + concatenation of <pfx> and the complete URI path, including the + query string, unless the "drop-query" option is specified (see + below). As a special case, if <pfx> equals exactly "/", then + nothing is inserted before the original URI. It allows one to + redirect to the same URL (for instance, to insert a cookie). When + used in an "http-request" rule, <pfx> value follows the log-format + rules and can include some dynamic values (see Custom Log Format + in section 8.2.4). + + <sch> With "redirect scheme", then the "Location" header is built by + concatenating <sch> with "://" then the first occurrence of the + "Host" header, and then the URI path, including the query string + unless the "drop-query" option is specified (see below). If no + path is found or if the path is "*", then "/" is used instead. If + no "Host" header is found, then an empty host component will be + returned, which most recent browsers interpret as redirecting to + the same host. This directive is mostly used to redirect HTTP to + HTTPS. When used in an "http-request" rule, <sch> value follows + the log-format rules and can include some dynamic values (see + Custom Log Format in section 8.2.4). + + <code> The code is optional. It indicates which type of HTTP redirection + is desired. Only codes 301, 302, 303, 307 and 308 are supported, + with 302 used by default if no code is specified. 301 means + "Moved permanently", and a browser may cache the Location. 302 + means "Moved temporarily" and means that the browser should not + cache the redirection. 303 is equivalent to 302 except that the + browser will fetch the location with a GET method. 307 is just + like 302 but makes it clear that the same method must be reused. + Likewise, 308 replaces 301 if the same method must be used. + + <option> There are several options which can be specified to adjust the + expected behavior of a redirection : + + - "drop-query" + When this keyword is used in a prefix-based redirection, then the + location will be set without any possible query-string, which is useful + for directing users to a non-secure page for instance. It has no effect + with a location-type redirect. + + - "append-slash" + This keyword may be used in conjunction with "drop-query" to redirect + users who use a URL not ending with a '/' to the same one with the '/'. + It can be useful to ensure that search engines will only see one URL. + For this, a return code 301 is preferred. + + - "ignore-empty" + This keyword only has effect when a location is produced using a log + format expression (i.e. when used in http-request or http-response). + It indicates that if the result of the expression is empty, the rule + should silently be skipped. The main use is to allow mass-redirects + of known paths using a simple map. + + - "set-cookie NAME[=value]" + A "Set-Cookie" header will be added with NAME (and optionally "=value") + to the response. This is sometimes used to indicate that a user has + been seen, for instance to protect against some types of DoS. No other + cookie option is added, so the cookie will be a session cookie. Note + that for a browser, a sole cookie name without an equal sign is + different from a cookie with an equal sign. + + - "clear-cookie NAME[=]" + A "Set-Cookie" header will be added with NAME (and optionally "="), but + with the "Max-Age" attribute set to zero. This will tell the browser to + delete this cookie. It is useful for instance on logout pages. It is + important to note that clearing the cookie "NAME" will not remove a + cookie set with "NAME=value". You have to clear the cookie "NAME=" for + that, because the browser makes the difference. + + Example: move the login URL only to HTTPS. + acl clear dst_port 80 + acl secure dst_port 8080 + acl login_page url_beg /login + acl logout url_beg /logout + acl uid_given url_reg /login?userid=[^&]+ + acl cookie_set hdr_sub(cookie) SEEN=1 + + redirect prefix https://mysite.com set-cookie SEEN=1 if !cookie_set + redirect prefix https://mysite.com if login_page !secure + redirect prefix http://mysite.com drop-query if login_page !uid_given + redirect location http://mysite.com/ if !login_page secure + redirect location / clear-cookie USERID= if logout + + Example: send redirects for request for articles without a '/'. + acl missing_slash path_reg ^/article/[^/]*$ + redirect code 301 prefix / drop-query append-slash if missing_slash + + Example: redirect all HTTP traffic to HTTPS when SSL is handled by HAProxy. + redirect scheme https if !{ ssl_fc } + + Example: append 'www.' prefix in front of all hosts not having it + http-request redirect code 301 location \ + http://www.%[hdr(host)]%[capture.req.uri] \ + unless { hdr_beg(host) -i www } + + Example: permanently redirect only old URLs to new ones + http-request redirect code 301 location \ + %[path,map_str(old-blog-articles.map)] ignore-empty + + See section 7 about ACL usage. + + +retries <value> + Set the number of retries to perform on a server after a failure + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <value> is the number of times a request or connection attempt should be + retried on a server after a failure. + + By default, retries apply only to new connection attempts. However, when + the "retry-on" directive is used, other conditions might trigger a retry + (e.g. empty response, undesired status code), and each of them will count + one attempt, and when the total number attempts reaches the value here, an + error will be returned. + + In order to avoid immediate reconnections to a server which is restarting, + a turn-around timer of min("timeout connect", one second) is applied before + a retry occurs on the same server. + + When "option redispatch" is set, some retries may be performed on another + server even if a cookie references a different server. By default this will + only be the last retry unless an argument is passed to "option redispatch". + + See also : "option redispatch" + + +retry-on [space-delimited list of keywords] + Specify when to attempt to automatically retry a failed request. + This setting is only valid when "mode" is set to http and is silently ignored + otherwise. + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <keywords> is a space-delimited list of keywords or HTTP status codes, each + representing a type of failure event on which an attempt to + retry the request is desired. Please read the notes at the + bottom before changing this setting. The following keywords are + supported : + + none never retry + + conn-failure retry when the connection or the SSL handshake failed + and the request could not be sent. This is the default. + + empty-response retry when the server connection was closed after part + of the request was sent, and nothing was received from + the server. This type of failure may be caused by the + request timeout on the server side, poor network + condition, or a server crash or restart while + processing the request. + + junk-response retry when the server returned something not looking + like a complete HTTP response. This includes partial + responses headers as well as non-HTTP contents. It + usually is a bad idea to retry on such events, which + may be caused a configuration issue (wrong server port) + or by the request being harmful to the server (buffer + overflow attack for example). + + response-timeout the server timeout stroke while waiting for the server + to respond to the request. This may be caused by poor + network condition, the reuse of an idle connection + which has expired on the path, or by the request being + extremely expensive to process. It generally is a bad + idea to retry on such events on servers dealing with + heavy database processing (full scans, etc) as it may + amplify denial of service attacks. + + 0rtt-rejected retry requests which were sent over early data and were + rejected by the server. These requests are generally + considered to be safe to retry. + + <status> any HTTP status code among "401" (Unauthorized), "403" + (Forbidden), "404" (Not Found), "408" (Request Timeout), + "425" (Too Early), "500" (Server Error), "501" (Not + Implemented), "502" (Bad Gateway), "503" (Service + Unavailable), "504" (Gateway Timeout). + + all-retryable-errors + retry request for any error that are considered + retryable. This currently activates "conn-failure", + "empty-response", "junk-response", "response-timeout", + "0rtt-rejected", "500", "502", "503", and "504". + + Using this directive replaces any previous settings with the new ones; it is + not cumulative. + + Please note that using anything other than "none" and "conn-failure" requires + to allocate a buffer and copy the whole request into it, so it has memory and + performance impacts. Requests not fitting in a single buffer will never be + retried (see the global tune.bufsize setting). + + You have to make sure the application has a replay protection mechanism built + in such as a unique transaction IDs passed in requests, or that replaying the + same request has no consequence, or it is very dangerous to use any retry-on + value beside "conn-failure" and "none". Static file servers and caches are + generally considered safe against any type of retry. Using a status code can + be useful to quickly leave a server showing an abnormal behavior (out of + memory, file system issues, etc), but in this case it may be a good idea to + immediately redispatch the connection to another server (please see "option + redispatch" for this). Last, it is important to understand that most causes + of failures are the requests themselves and that retrying a request causing a + server to misbehave will often make the situation even worse for this server, + or for the whole service in case of redispatch. + + Unless you know exactly how the application deals with replayed requests, you + should not use this directive. + + The default is "conn-failure". + + Example: + retry-on 503 504 + + See also: "retries", "option redispatch", "tune.bufsize" + +server <name> <address>[:[port]] [param*] + Declare a server in a backend + May be used in sections : defaults | frontend | listen | backend + no | no | yes | yes + Arguments : + <name> is the internal name assigned to this server. This name will + appear in logs and alerts. If "http-send-name-header" is + set, it will be added to the request header sent to the server. + + <address> is the IPv4 or IPv6 address of the server. Alternatively, a + resolvable hostname is supported, but this name will be resolved + during start-up. Address "0.0.0.0" or "*" has a special meaning. + It indicates that the connection will be forwarded to the same IP + address as the one from the client connection. This is useful in + transparent proxy architectures where the client's connection is + intercepted and HAProxy must forward to the original destination + address. This is more or less what the "transparent" keyword does + except that with a server it's possible to limit concurrency and + to report statistics. Optionally, an address family prefix may be + used before the address to force the family regardless of the + address format, which can be useful to specify a path to a unix + socket with no slash ('/'). Currently supported prefixes are : + - 'ipv4@' -> address is always IPv4 + - 'ipv6@' -> address is always IPv6 + - 'unix@' -> address is a path to a local unix socket + - 'abns@' -> address is in abstract namespace (Linux only) + - 'sockpair@' -> address is the FD of a connected unix + socket or of a socketpair. During a connection, the + backend creates a pair of connected sockets, and passes + one of them over the FD. The bind part will use the + received socket as the client FD. Should be used + carefully. + You may want to reference some environment variables in the + address parameter, see section 2.3 about environment + variables. The "init-addr" setting can be used to modify the way + IP addresses should be resolved upon startup. + + <port> is an optional port specification. If set, all connections will + be sent to this port. If unset, the same port the client + connected to will be used. The port may also be prefixed by a "+" + or a "-". In this case, the server's port will be determined by + adding this value to the client's port. + + <param*> is a list of parameters for this server. The "server" keywords + accepts an important number of options and has a complete section + dedicated to it. Please refer to section 5 for more details. + + Examples : + server first 10.1.1.1:1080 cookie first check inter 1000 + server second 10.1.1.2:1080 cookie second check inter 1000 + server transp ipv4@ + server backup "${SRV_BACKUP}:1080" backup + server www1_dc1 "${LAN_DC1}.101:80" + server www1_dc2 "${LAN_DC2}.101:80" + + Note: regarding Linux's abstract namespace sockets, HAProxy uses the whole + sun_path length is used for the address length. Some other programs + such as socat use the string length only by default. Pass the option + ",unix-tightsocklen=0" to any abstract socket definition in socat to + make it compatible with HAProxy's. + + See also: "default-server", "http-send-name-header" and section 5 about + server options + +server-state-file-name [ { use-backend-name | <file> } ] + Set the server state file to read, load and apply to servers available in + this backend. + May be used in sections: defaults | frontend | listen | backend + no | no | yes | yes + + It only applies when the directive "load-server-state-from-file" is set to + "local". When <file> is not provided, if "use-backend-name" is used or if + this directive is not set, then backend name is used. If <file> starts with a + slash '/', then it is considered as an absolute path. Otherwise, <file> is + concatenated to the global directive "server-state-base". + + Example: the minimal configuration below would make HAProxy look for the + state server file '/etc/haproxy/states/bk': + + global + server-state-file-base /etc/haproxy/states + + backend bk + load-server-state-from-file + + See also: "server-state-base", "load-server-state-from-file", and + "show servers state" + +server-template <prefix> <num | range> <fqdn>[:<port>] [params*] + Set a template to initialize servers with shared parameters. + The names of these servers are built from <prefix> and <num | range> parameters. + May be used in sections : defaults | frontend | listen | backend + no | no | yes | yes + + Arguments: + <prefix> A prefix for the server names to be built. + + <num | range> + If <num> is provided, this template initializes <num> servers + with 1 up to <num> as server name suffixes. A range of numbers + <num_low>-<num_high> may also be used to use <num_low> up to + <num_high> as server name suffixes. + + <fqdn> A FQDN for all the servers this template initializes. + + <port> Same meaning as "server" <port> argument (see "server" keyword). + + <params*> + Remaining server parameters among all those supported by "server" + keyword. + + Examples: + # Initializes 3 servers with srv1, srv2 and srv3 as names, + # google.com as FQDN, and health-check enabled. + server-template srv 1-3 google.com:80 check + + # or + server-template srv 3 google.com:80 check + + # would be equivalent to: + server srv1 google.com:80 check + server srv2 google.com:80 check + server srv3 google.com:80 check + + + +source <addr>[:<port>] [usesrc { <addr2>[:<port2>] | client | clientip } ] +source <addr>[:<port>] [usesrc { <addr2>[:<port2>] | hdr_ip(<hdr>[,<occ>]) } ] +source <addr>[:<port>] [interface <name>] + Set the source address for outgoing connections + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <addr> is the IPv4 address HAProxy will bind to before connecting to a + server. This address is also used as a source for health checks. + + The default value of 0.0.0.0 means that the system will select + the most appropriate address to reach its destination. Optionally + an address family prefix may be used before the address to force + the family regardless of the address format, which can be useful + to specify a path to a unix socket with no slash ('/'). Currently + supported prefixes are : + - 'ipv4@' -> address is always IPv4 + - 'ipv6@' -> address is always IPv6 + - 'unix@' -> address is a path to a local unix socket + - 'abns@' -> address is in abstract namespace (Linux only) + You may want to reference some environment variables in the + address parameter, see section 2.3 about environment variables. + + <port> is an optional port. It is normally not needed but may be useful + in some very specific contexts. The default value of zero means + the system will select a free port. Note that port ranges are not + supported in the backend. If you want to force port ranges, you + have to specify them on each "server" line. + + <addr2> is the IP address to present to the server when connections are + forwarded in full transparent proxy mode. This is currently only + supported on some patched Linux kernels. When this address is + specified, clients connecting to the server will be presented + with this address, while health checks will still use the address + <addr>. + + <port2> is the optional port to present to the server when connections + are forwarded in full transparent proxy mode (see <addr2> above). + The default value of zero means the system will select a free + port. + + <hdr> is the name of a HTTP header in which to fetch the IP to bind to. + This is the name of a comma-separated header list which can + contain multiple IP addresses. By default, the last occurrence is + used. This is designed to work with the X-Forwarded-For header + and to automatically bind to the client's IP address as seen + by previous proxy, typically Stunnel. In order to use another + occurrence from the last one, please see the <occ> parameter + below. When the header (or occurrence) is not found, no binding + is performed so that the proxy's default IP address is used. Also + keep in mind that the header name is case insensitive, as for any + HTTP header. + + <occ> is the occurrence number of a value to be used in a multi-value + header. This is to be used in conjunction with "hdr_ip(<hdr>)", + in order to specify which occurrence to use for the source IP + address. Positive values indicate a position from the first + occurrence, 1 being the first one. Negative values indicate + positions relative to the last one, -1 being the last one. This + is helpful for situations where an X-Forwarded-For header is set + at the entry point of an infrastructure and must be used several + proxy layers away. When this value is not specified, -1 is + assumed. Passing a zero here disables the feature. + + <name> is an optional interface name to which to bind to for outgoing + traffic. On systems supporting this features (currently, only + Linux), this allows one to bind all traffic to the server to + this interface even if it is not the one the system would select + based on routing tables. This should be used with extreme care. + Note that using this option requires root privileges. + + The "source" keyword is useful in complex environments where a specific + address only is allowed to connect to the servers. It may be needed when a + private address must be used through a public gateway for instance, and it is + known that the system cannot determine the adequate source address by itself. + + An extension which is available on certain patched Linux kernels may be used + through the "usesrc" optional keyword. It makes it possible to connect to the + servers with an IP address which does not belong to the system itself. This + is called "full transparent proxy mode". For this to work, the destination + servers have to route their traffic back to this address through the machine + running HAProxy, and IP forwarding must generally be enabled on this machine. + + In this "full transparent proxy" mode, it is possible to force a specific IP + address to be presented to the servers. This is not much used in fact. A more + common use is to tell HAProxy to present the client's IP address. For this, + there are two methods : + + - present the client's IP and port addresses. This is the most transparent + mode, but it can cause problems when IP connection tracking is enabled on + the machine, because a same connection may be seen twice with different + states. However, this solution presents the huge advantage of not + limiting the system to the 64k outgoing address+port couples, because all + of the client ranges may be used. + + - present only the client's IP address and select a spare port. This + solution is still quite elegant but slightly less transparent (downstream + firewalls logs will not match upstream's). It also presents the downside + of limiting the number of concurrent connections to the usual 64k ports. + However, since the upstream and downstream ports are different, local IP + connection tracking on the machine will not be upset by the reuse of the + same session. + + This option sets the default source for all servers in the backend. It may + also be specified in a "defaults" section. Finer source address specification + is possible at the server level using the "source" server option. Refer to + section 5 for more information. + + In order to work, "usesrc" requires root privileges. + + Examples : + backend private + # Connect to the servers using our 192.168.1.200 source address + source 192.168.1.200 + + backend transparent_ssl1 + # Connect to the SSL farm from the client's source address + source 192.168.1.200 usesrc clientip + + backend transparent_ssl2 + # Connect to the SSL farm from the client's source address and port + # not recommended if IP conntrack is present on the local machine. + source 192.168.1.200 usesrc client + + backend transparent_ssl3 + # Connect to the SSL farm from the client's source address. It + # is more conntrack-friendly. + source 192.168.1.200 usesrc clientip + + backend transparent_smtp + # Connect to the SMTP farm from the client's source address/port + # with Tproxy version 4. + source 0.0.0.0 usesrc clientip + + backend transparent_http + # Connect to the servers using the client's IP as seen by previous + # proxy. + source 0.0.0.0 usesrc hdr_ip(x-forwarded-for,-1) + + See also : the "source" server option in section 5, the Tproxy patches for + the Linux kernel on www.balabit.com, the "bind" keyword. + + +srvtcpka-cnt <count> + Sets the maximum number of keepalive probes TCP should send before dropping + the connection on the server side. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <count> is the maximum number of keepalive probes. + + This keyword corresponds to the socket option TCP_KEEPCNT. If this keyword + is not specified, system-wide TCP parameter (tcp_keepalive_probes) is used. + The availability of this setting depends on the operating system. It is + known to work on Linux. + + See also : "option srvtcpka", "srvtcpka-idle", "srvtcpka-intvl". + + +srvtcpka-idle <timeout> + Sets the time the connection needs to remain idle before TCP starts sending + keepalive probes, if enabled the sending of TCP keepalive packets on the + server side. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <timeout> is the time the connection needs to remain idle before TCP starts + sending keepalive probes. It is specified in seconds by default, + but can be in any other unit if the number is suffixed by the + unit, as explained at the top of this document. + + This keyword corresponds to the socket option TCP_KEEPIDLE. If this keyword + is not specified, system-wide TCP parameter (tcp_keepalive_time) is used. + The availability of this setting depends on the operating system. It is + known to work on Linux. + + See also : "option srvtcpka", "srvtcpka-cnt", "srvtcpka-intvl". + + +srvtcpka-intvl <timeout> + Sets the time between individual keepalive probes on the server side. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <timeout> is the time between individual keepalive probes. It is specified + in seconds by default, but can be in any other unit if the number + is suffixed by the unit, as explained at the top of this + document. + + This keyword corresponds to the socket option TCP_KEEPINTVL. If this keyword + is not specified, system-wide TCP parameter (tcp_keepalive_intvl) is used. + The availability of this setting depends on the operating system. It is + known to work on Linux. + + See also : "option srvtcpka", "srvtcpka-cnt", "srvtcpka-idle". + + +stats admin { if | unless } <cond> + Enable statistics admin level if/unless a condition is matched + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | yes + + This statement enables the statistics admin level if/unless a condition is + matched. + + The admin level allows to enable/disable servers from the web interface. By + default, statistics page is read-only for security reasons. + + Currently, the POST request is limited to the buffer size minus the reserved + buffer space, which means that if the list of servers is too long, the + request won't be processed. It is recommended to alter few servers at a + time. + + Example : + # statistics admin level only for localhost + backend stats_localhost + stats enable + stats admin if LOCALHOST + + Example : + # statistics admin level always enabled because of the authentication + backend stats_auth + stats enable + stats auth admin:AdMiN123 + stats admin if TRUE + + Example : + # statistics admin level depends on the authenticated user + userlist stats-auth + group admin users admin + user admin insecure-password AdMiN123 + group readonly users haproxy + user haproxy insecure-password haproxy + + backend stats_auth + stats enable + acl AUTH http_auth(stats-auth) + acl AUTH_ADMIN http_auth_group(stats-auth) admin + stats http-request auth unless AUTH + stats admin if AUTH_ADMIN + + See also : "stats enable", "stats auth", "stats http-request", section 3.4 + about userlists and section 7 about ACL usage. + + +stats auth <user>:<passwd> + Enable statistics with authentication and grant access to an account + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <user> is a user name to grant access to + + <passwd> is the cleartext password associated to this user + + This statement enables statistics with default settings, and restricts access + to declared users only. It may be repeated as many times as necessary to + allow as many users as desired. When a user tries to access the statistics + without a valid account, a "401 Forbidden" response will be returned so that + the browser asks the user to provide a valid user and password. The real + which will be returned to the browser is configurable using "stats realm". + + Since the authentication method is HTTP Basic Authentication, the passwords + circulate in cleartext on the network. Thus, it was decided that the + configuration file would also use cleartext passwords to remind the users + that those ones should not be sensitive and not shared with any other account. + + It is also possible to reduce the scope of the proxies which appear in the + report using "stats scope". + + Though this statement alone is enough to enable statistics reporting, it is + recommended to set all other settings in order to avoid relying on default + unobvious parameters. + + Example : + # public access (limited to this backend only) + backend public_www + server srv1 192.168.0.1:80 + stats enable + stats hide-version + stats scope . + stats uri /admin?stats + stats realm HAProxy\ Statistics + stats auth admin1:AdMiN123 + stats auth admin2:AdMiN321 + + # internal monitoring access (unlimited) + backend private_monitoring + stats enable + stats uri /admin?stats + stats refresh 5s + + See also : "stats enable", "stats realm", "stats scope", "stats uri" + + +stats enable + Enable statistics reporting with default settings + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + This statement enables statistics reporting with default settings defined + at build time. Unless stated otherwise, these settings are used : + - stats uri : /haproxy?stats + - stats realm : "HAProxy Statistics" + - stats auth : no authentication + - stats scope : no restriction + + Though this statement alone is enough to enable statistics reporting, it is + recommended to set all other settings in order to avoid relying on default + unobvious parameters. + + Example : + # public access (limited to this backend only) + backend public_www + server srv1 192.168.0.1:80 + stats enable + stats hide-version + stats scope . + stats uri /admin?stats + stats realm HAProxy\ Statistics + stats auth admin1:AdMiN123 + stats auth admin2:AdMiN321 + + # internal monitoring access (unlimited) + backend private_monitoring + stats enable + stats uri /admin?stats + stats refresh 5s + + See also : "stats auth", "stats realm", "stats uri" + + +stats hide-version + Enable statistics and hide HAProxy version reporting + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + By default, the stats page reports some useful status information along with + the statistics. Among them is HAProxy's version. However, it is generally + considered dangerous to report precise version to anyone, as it can help them + target known weaknesses with specific attacks. The "stats hide-version" + statement removes the version from the statistics report. This is recommended + for public sites or any site with a weak login/password. + + Though this statement alone is enough to enable statistics reporting, it is + recommended to set all other settings in order to avoid relying on default + unobvious parameters. + + Example : + # public access (limited to this backend only) + backend public_www + server srv1 192.168.0.1:80 + stats enable + stats hide-version + stats scope . + stats uri /admin?stats + stats realm HAProxy\ Statistics + stats auth admin1:AdMiN123 + stats auth admin2:AdMiN321 + + # internal monitoring access (unlimited) + backend private_monitoring + stats enable + stats uri /admin?stats + stats refresh 5s + + See also : "stats auth", "stats enable", "stats realm", "stats uri" + + +stats http-request { allow | deny | auth [realm <realm>] } + [ { if | unless } <condition> ] + Access control for statistics + + May be used in sections: defaults | frontend | listen | backend + no | no | yes | yes + + As "http-request", these set of options allow to fine control access to + statistics. Each option may be followed by if/unless and acl. + First option with matched condition (or option without condition) is final. + For "deny" a 403 error will be returned, for "allow" normal processing is + performed, for "auth" a 401/407 error code is returned so the client + should be asked to enter a username and password. + + There is no fixed limit to the number of http-request statements per + instance. + + See also : "http-request", section 3.4 about userlists and section 7 + about ACL usage. + + +stats realm <realm> + Enable statistics and set authentication realm + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <realm> is the name of the HTTP Basic Authentication realm reported to + the browser. The browser uses it to display it in the pop-up + inviting the user to enter a valid username and password. + + The realm is read as a single word, so any spaces in it should be escaped + using a backslash ('\'). + + This statement is useful only in conjunction with "stats auth" since it is + only related to authentication. + + Though this statement alone is enough to enable statistics reporting, it is + recommended to set all other settings in order to avoid relying on default + unobvious parameters. + + Example : + # public access (limited to this backend only) + backend public_www + server srv1 192.168.0.1:80 + stats enable + stats hide-version + stats scope . + stats uri /admin?stats + stats realm HAProxy\ Statistics + stats auth admin1:AdMiN123 + stats auth admin2:AdMiN321 + + # internal monitoring access (unlimited) + backend private_monitoring + stats enable + stats uri /admin?stats + stats refresh 5s + + See also : "stats auth", "stats enable", "stats uri" + + +stats refresh <delay> + Enable statistics with automatic refresh + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <delay> is the suggested refresh delay, specified in seconds, which will + be returned to the browser consulting the report page. While the + browser is free to apply any delay, it will generally respect it + and refresh the page this every seconds. The refresh interval may + be specified in any other non-default time unit, by suffixing the + unit after the value, as explained at the top of this document. + + This statement is useful on monitoring displays with a permanent page + reporting the load balancer's activity. When set, the HTML report page will + include a link "refresh"/"stop refresh" so that the user can select whether + they want automatic refresh of the page or not. + + Though this statement alone is enough to enable statistics reporting, it is + recommended to set all other settings in order to avoid relying on default + unobvious parameters. + + Example : + # public access (limited to this backend only) + backend public_www + server srv1 192.168.0.1:80 + stats enable + stats hide-version + stats scope . + stats uri /admin?stats + stats realm HAProxy\ Statistics + stats auth admin1:AdMiN123 + stats auth admin2:AdMiN321 + + # internal monitoring access (unlimited) + backend private_monitoring + stats enable + stats uri /admin?stats + stats refresh 5s + + See also : "stats auth", "stats enable", "stats realm", "stats uri" + + +stats scope { <name> | "." } + Enable statistics and limit access scope + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <name> is the name of a listen, frontend or backend section to be + reported. The special name "." (a single dot) designates the + section in which the statement appears. + + When this statement is specified, only the sections enumerated with this + statement will appear in the report. All other ones will be hidden. This + statement may appear as many times as needed if multiple sections need to be + reported. Please note that the name checking is performed as simple string + comparisons, and that it is never checked that a give section name really + exists. + + Though this statement alone is enough to enable statistics reporting, it is + recommended to set all other settings in order to avoid relying on default + unobvious parameters. + + Example : + # public access (limited to this backend only) + backend public_www + server srv1 192.168.0.1:80 + stats enable + stats hide-version + stats scope . + stats uri /admin?stats + stats realm HAProxy\ Statistics + stats auth admin1:AdMiN123 + stats auth admin2:AdMiN321 + + # internal monitoring access (unlimited) + backend private_monitoring + stats enable + stats uri /admin?stats + stats refresh 5s + + See also : "stats auth", "stats enable", "stats realm", "stats uri" + + +stats show-desc [ <desc> ] + Enable reporting of a description on the statistics page. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + + <desc> is an optional description to be reported. If unspecified, the + description from global section is automatically used instead. + + This statement is useful for users that offer shared services to their + customers, where node or description should be different for each customer. + + Though this statement alone is enough to enable statistics reporting, it is + recommended to set all other settings in order to avoid relying on default + unobvious parameters. By default description is not shown. + + Example : + # internal monitoring access (unlimited) + backend private_monitoring + stats enable + stats show-desc Master node for Europe, Asia, Africa + stats uri /admin?stats + stats refresh 5s + + See also: "show-node", "stats enable", "stats uri" and "description" in + global section. + + +stats show-legends + Enable reporting additional information on the statistics page + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + Enable reporting additional information on the statistics page : + - cap: capabilities (proxy) + - mode: one of tcp, http or health (proxy) + - id: SNMP ID (proxy, socket, server) + - IP (socket, server) + - cookie (backend, server) + + Though this statement alone is enough to enable statistics reporting, it is + recommended to set all other settings in order to avoid relying on default + unobvious parameters. Default behavior is not to show this information. + + See also: "stats enable", "stats uri". + + +stats show-modules + Enable display of extra statistics module on the statistics page + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : none + + New columns are added at the end of the line containing the extra statistics + values as a tooltip. + + Though this statement alone is enough to enable statistics reporting, it is + recommended to set all other settings in order to avoid relying on default + unobvious parameters. Default behavior is not to show this information. + + See also: "stats enable", "stats uri". + + +stats show-node [ <name> ] + Enable reporting of a host name on the statistics page. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments: + <name> is an optional name to be reported. If unspecified, the + node name from global section is automatically used instead. + + This statement is useful for users that offer shared services to their + customers, where node or description might be different on a stats page + provided for each customer. Default behavior is not to show host name. + + Though this statement alone is enough to enable statistics reporting, it is + recommended to set all other settings in order to avoid relying on default + unobvious parameters. + + Example: + # internal monitoring access (unlimited) + backend private_monitoring + stats enable + stats show-node Europe-1 + stats uri /admin?stats + stats refresh 5s + + See also: "show-desc", "stats enable", "stats uri", and "node" in global + section. + + +stats uri <prefix> + Enable statistics and define the URI prefix to access them + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <prefix> is the prefix of any URI which will be redirected to stats. This + prefix may contain a question mark ('?') to indicate part of a + query string. + + The statistics URI is intercepted on the relayed traffic, so it appears as a + page within the normal application. It is strongly advised to ensure that the + selected URI will never appear in the application, otherwise it will never be + possible to reach it in the application. + + The default URI compiled in HAProxy is "/haproxy?stats", but this may be + changed at build time, so it's better to always explicitly specify it here. + It is generally a good idea to include a question mark in the URI so that + intermediate proxies refrain from caching the results. Also, since any string + beginning with the prefix will be accepted as a stats request, the question + mark helps ensuring that no valid URI will begin with the same words. + + It is sometimes very convenient to use "/" as the URI prefix, and put that + statement in a "listen" instance of its own. That makes it easy to dedicate + an address or a port to statistics only. + + Though this statement alone is enough to enable statistics reporting, it is + recommended to set all other settings in order to avoid relying on default + unobvious parameters. + + Example : + # public access (limited to this backend only) + backend public_www + server srv1 192.168.0.1:80 + stats enable + stats hide-version + stats scope . + stats uri /admin?stats + stats realm HAProxy\ Statistics + stats auth admin1:AdMiN123 + stats auth admin2:AdMiN321 + + # internal monitoring access (unlimited) + backend private_monitoring + stats enable + stats uri /admin?stats + stats refresh 5s + + See also : "stats auth", "stats enable", "stats realm" + + +stick match <pattern> [table <table>] [{if | unless} <cond>] + Define a request pattern matching condition to stick a user to a server + May be used in sections : defaults | frontend | listen | backend + no | no | yes | yes + + Arguments : + <pattern> is a sample expression rule as described in section 7.3. It + describes what elements of the incoming request or connection + will be analyzed in the hope to find a matching entry in a + stickiness table. This rule is mandatory. + + <table> is an optional stickiness table name. If unspecified, the same + backend's table is used. A stickiness table is declared using + the "stick-table" statement. + + <cond> is an optional matching condition. It makes it possible to match + on a certain criterion only when other conditions are met (or + not met). For instance, it could be used to match on a source IP + address except when a request passes through a known proxy, in + which case we'd match on a header containing that IP address. + + Some protocols or applications require complex stickiness rules and cannot + always simply rely on cookies nor hashing. The "stick match" statement + describes a rule to extract the stickiness criterion from an incoming request + or connection. See section 7 for a complete list of possible patterns and + transformation rules. + + The table has to be declared using the "stick-table" statement. It must be of + a type compatible with the pattern. By default it is the one which is present + in the same backend. It is possible to share a table with other backends by + referencing it using the "table" keyword. If another table is referenced, + the server's ID inside the backends are used. By default, all server IDs + start at 1 in each backend, so the server ordering is enough. But in case of + doubt, it is highly recommended to force server IDs using their "id" setting. + + It is possible to restrict the conditions where a "stick match" statement + will apply, using "if" or "unless" followed by a condition. See section 7 for + ACL based conditions. + + There is no limit on the number of "stick match" statements. The first that + applies and matches will cause the request to be directed to the same server + as was used for the request which created the entry. That way, multiple + matches can be used as fallbacks. + + The stick rules are checked after the persistence cookies, so they will not + affect stickiness if a cookie has already been used to select a server. That + way, it becomes very easy to insert cookies and match on IP addresses in + order to maintain stickiness between HTTP and HTTPS. + + Example : + # forward SMTP users to the same server they just used for POP in the + # last 30 minutes + backend pop + mode tcp + balance roundrobin + stick store-request src + stick-table type ip size 200k expire 30m + server s1 192.168.1.1:110 + server s2 192.168.1.1:110 + + backend smtp + mode tcp + balance roundrobin + stick match src table pop + server s1 192.168.1.1:25 + server s2 192.168.1.1:25 + + See also : "stick-table", "stick on", and section 7 about ACLs and samples + fetching. + + +stick on <pattern> [table <table>] [{if | unless} <condition>] + Define a request pattern to associate a user to a server + May be used in sections : defaults | frontend | listen | backend + no | no | yes | yes + + Note : This form is exactly equivalent to "stick match" followed by + "stick store-request", all with the same arguments. Please refer + to both keywords for details. It is only provided as a convenience + for writing more maintainable configurations. + + Examples : + # The following form ... + stick on src table pop if !localhost + + # ...is strictly equivalent to this one : + stick match src table pop if !localhost + stick store-request src table pop if !localhost + + + # Use cookie persistence for HTTP, and stick on source address for HTTPS as + # well as HTTP without cookie. Share the same table between both accesses. + backend http + mode http + balance roundrobin + stick on src table https + cookie SRV insert indirect nocache + server s1 192.168.1.1:80 cookie s1 + server s2 192.168.1.1:80 cookie s2 + + backend https + mode tcp + balance roundrobin + stick-table type ip size 200k expire 30m + stick on src + server s1 192.168.1.1:443 + server s2 192.168.1.1:443 + + See also : "stick match", "stick store-request". + + +stick store-request <pattern> [table <table>] [{if | unless} <condition>] + Define a request pattern used to create an entry in a stickiness table + May be used in sections : defaults | frontend | listen | backend + no | no | yes | yes + + Arguments : + <pattern> is a sample expression rule as described in section 7.3. It + describes what elements of the incoming request or connection + will be analyzed, extracted and stored in the table once a + server is selected. + + <table> is an optional stickiness table name. If unspecified, the same + backend's table is used. A stickiness table is declared using + the "stick-table" statement. + + <cond> is an optional storage condition. It makes it possible to store + certain criteria only when some conditions are met (or not met). + For instance, it could be used to store the source IP address + except when the request passes through a known proxy, in which + case we'd store a converted form of a header containing that IP + address. + + Some protocols or applications require complex stickiness rules and cannot + always simply rely on cookies nor hashing. The "stick store-request" statement + describes a rule to decide what to extract from the request and when to do + it, in order to store it into a stickiness table for further requests to + match it using the "stick match" statement. Obviously the extracted part must + make sense and have a chance to be matched in a further request. Storing a + client's IP address for instance often makes sense. Storing an ID found in a + URL parameter also makes sense. Storing a source port will almost never make + any sense because it will be randomly matched. See section 7 for a complete + list of possible patterns and transformation rules. + + The table has to be declared using the "stick-table" statement. It must be of + a type compatible with the pattern. By default it is the one which is present + in the same backend. It is possible to share a table with other backends by + referencing it using the "table" keyword. If another table is referenced, + the server's ID inside the backends are used. By default, all server IDs + start at 1 in each backend, so the server ordering is enough. But in case of + doubt, it is highly recommended to force server IDs using their "id" setting. + + It is possible to restrict the conditions where a "stick store-request" + statement will apply, using "if" or "unless" followed by a condition. This + condition will be evaluated while parsing the request, so any criteria can be + used. See section 7 for ACL based conditions. + + There is no limit on the number of "stick store-request" statements, but + there is a limit of 8 simultaneous stores per request or response. This + makes it possible to store up to 8 criteria, all extracted from either the + request or the response, regardless of the number of rules. Only the 8 first + ones which match will be kept. Using this, it is possible to feed multiple + tables at once in the hope to increase the chance to recognize a user on + another protocol or access method. Using multiple store-request rules with + the same table is possible and may be used to find the best criterion to rely + on, by arranging the rules by decreasing preference order. Only the first + extracted criterion for a given table will be stored. All subsequent store- + request rules referencing the same table will be skipped and their ACLs will + not be evaluated. + + The "store-request" rules are evaluated once the server connection has been + established, so that the table will contain the real server that processed + the request. + + Example : + # forward SMTP users to the same server they just used for POP in the + # last 30 minutes + backend pop + mode tcp + balance roundrobin + stick store-request src + stick-table type ip size 200k expire 30m + server s1 192.168.1.1:110 + server s2 192.168.1.1:110 + + backend smtp + mode tcp + balance roundrobin + stick match src table pop + server s1 192.168.1.1:25 + server s2 192.168.1.1:25 + + See also : "stick-table", "stick on", about ACLs and sample fetching. + + +stick-table type {ip | integer | string [len <length>] | binary [len <length>]} + size <size> [expire <expire>] [nopurge] [peers <peersect>] [srvkey <srvkey>] + [store <data_type>]* + Configure the stickiness table for the current section + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | yes + + Arguments : + ip a table declared with "type ip" will only store IPv4 addresses. + This form is very compact (about 50 bytes per entry) and allows + very fast entry lookup and stores with almost no overhead. This + is mainly used to store client source IP addresses. + + ipv6 a table declared with "type ipv6" will only store IPv6 addresses. + This form is very compact (about 60 bytes per entry) and allows + very fast entry lookup and stores with almost no overhead. This + is mainly used to store client source IP addresses. + + integer a table declared with "type integer" will store 32bit integers + which can represent a client identifier found in a request for + instance. + + string a table declared with "type string" will store substrings of up + to <len> characters. If the string provided by the pattern + extractor is larger than <len>, it will be truncated before + being stored. During matching, at most <len> characters will be + compared between the string in the table and the extracted + pattern. When not specified, the string is automatically limited + to 32 characters. + + binary a table declared with "type binary" will store binary blocks + of <len> bytes. If the block provided by the pattern + extractor is larger than <len>, it will be truncated before + being stored. If the block provided by the sample expression + is shorter than <len>, it will be padded by 0. When not + specified, the block is automatically limited to 32 bytes. + + <length> is the maximum number of characters that will be stored in a + "string" type table (See type "string" above). Or the number + of bytes of the block in "binary" type table. Be careful when + changing this parameter as memory usage will proportionally + increase. + + <size> is the maximum number of entries that can fit in the table. This + value directly impacts memory usage. Count approximately + 50 bytes per entry, plus the size of a string if any. The size + supports suffixes "k", "m", "g" for 2^10, 2^20 and 2^30 factors. + + [nopurge] indicates that we refuse to purge older entries when the table + is full. When not specified and the table is full when HAProxy + wants to store an entry in it, it will flush a few of the oldest + entries in order to release some space for the new ones. This is + most often the desired behavior. In some specific cases, it + be desirable to refuse new entries instead of purging the older + ones. That may be the case when the amount of data to store is + far above the hardware limits and we prefer not to offer access + to new clients than to reject the ones already connected. When + using this parameter, be sure to properly set the "expire" + parameter (see below). + + <peersect> is the name of the peers section to use for replication. Entries + which associate keys to server IDs are kept synchronized with + the remote peers declared in this section. All entries are also + automatically learned from the local peer (old process) during a + soft restart. + + <expire> defines the maximum duration of an entry in the table since it + was last created, refreshed using 'track-sc' or matched using + 'stick match' or 'stick on' rule. The expiration delay is + defined using the standard time format, similarly as the various + timeouts. The maximum duration is slightly above 24 days. See + section 2.5 for more information. If this delay is not specified, + the session won't automatically expire, but older entries will + be removed once full. Be sure not to use the "nopurge" parameter + if not expiration delay is specified. + Note: 'table_*' converters performs lookups but won't update touch + expire since they don't require 'track-sc'. + + <srvkey> specifies how each server is identified for the purposes of the + stick table. The valid values are "name" and "addr". If "name" is + given, then <name> argument for the server (may be generated by + a template). If "addr" is given, then the server is identified + by its current network address, including the port. "addr" is + especially useful if you are using service discovery to generate + the addresses for servers with peered stick-tables and want + to consistently use the same host across peers for a stickiness + token. + + <data_type> is used to store additional information in the stick-table. This + may be used by ACLs in order to control various criteria related + to the activity of the client matching the stick-table. For each + item specified here, the size of each entry will be inflated so + that the additional data can fit. Several data types may be + stored with an entry. Multiple data types may be specified after + the "store" keyword, as a comma-separated list. Alternatively, + it is possible to repeat the "store" keyword followed by one or + several data types. Except for the "server_id" type which is + automatically detected and enabled, all data types must be + explicitly declared to be stored. If an ACL references a data + type which is not stored, the ACL will simply not match. Some + data types require an argument which must be passed just after + the type between parenthesis. See below for the supported data + types and their arguments. + + The data types that can be stored with an entry are the following : + - server_id : this is an integer which holds the numeric ID of the server a + request was assigned to. It is used by the "stick match", "stick store", + and "stick on" rules. It is automatically enabled when referenced. + + - gpc(<nb>) : General Purpose Counters Array of <nb> elements. This is an + array of positive 32-bit integers which may be used to count anything. + Most of the time they will be used as a incremental counters on some + entries, for instance to note that a limit is reached and trigger some + actions. This array is limited to a maximum of 100 elements: + gpc0 to gpc99, to ensure that the build of a peer update + message can fit into the buffer. Users should take in consideration + that a large amount of counters will increase the data size and the + traffic load using peers protocol since all data/counters are pushed + each time any of them is updated. + This data_type will exclude the usage of the legacy data_types 'gpc0' + and 'gpc1' on the same table. Using the 'gpc' array data_type, all 'gpc0' + and 'gpc1' related fetches and actions will apply to the two first + elements of this array. + + - gpc_rate(<nb>,<period>) : Array of increment rates of General Purpose + Counters over a period. Those elements are positive 32-bit integers which + may be used for anything. Just like <gpc>, the count events, but instead + of keeping a cumulative number, they maintain the rate at which the + counter is incremented. Most of the time it will be used to measure the + frequency of occurrence of certain events (e.g. requests to a specific + URL). This array is limited to a maximum of 100 elements: gpt(100) + allowing the storage of gpc0 to gpc99, to ensure that the build of a peer + update message can fit into the buffer. + The array cannot contain less than 1 element: use gpc(1) if you want to + store only the counter gpc0. + Users should take in consideration that a large amount of + counters will increase the data size and the traffic load using peers + protocol since all data/counters are pushed each time any of them is + updated. + This data_type will exclude the usage of the legacy data_types + 'gpc0_rate' and 'gpc1_rate' on the same table. Using the 'gpc_rate' + array data_type, all 'gpc0' and 'gpc1' related fetches and actions + will apply to the two first elements of this array. + + - gpc0 : first General Purpose Counter. It is a positive 32-bit integer + integer which may be used for anything. Most of the time it will be used + to put a special tag on some entries, for instance to note that a + specific behavior was detected and must be known for future matches. + + - gpc0_rate(<period>) : increment rate of the first General Purpose Counter + over a period. It is a positive 32-bit integer integer which may be used + for anything. Just like <gpc0>, it counts events, but instead of keeping + a cumulative number, it maintains the rate at which the counter is + incremented. Most of the time it will be used to measure the frequency of + occurrence of certain events (e.g. requests to a specific URL). + + - gpc1 : second General Purpose Counter. It is a positive 32-bit integer + integer which may be used for anything. Most of the time it will be used + to put a special tag on some entries, for instance to note that a + specific behavior was detected and must be known for future matches. + + - gpc1_rate(<period>) : increment rate of the second General Purpose Counter + over a period. It is a positive 32-bit integer integer which may be used + for anything. Just like <gpc1>, it counts events, but instead of keeping + a cumulative number, it maintains the rate at which the counter is + incremented. Most of the time it will be used to measure the frequency of + occurrence of certain events (e.g. requests to a specific URL). + + - gpt(<nb>) : General Purpose Tags Array of <nb> elements. This is an array + of positive 32-bit integers which may be used for anything. + Most of the time they will be used to put a special tags on some entries, + for instance to note that a specific behavior was detected and must be + known for future matches. This array is limited to a maximum of 100 + elements: gpt(100) allowing the storage of gpt0 to gpt99, to ensure that + the build of a peer update message can fit into the buffer. + The array cannot contain less than 1 element: use gpt(1) if you want to + to store only the tag gpt0. + Users should take in consideration that a large amount of counters will + increase the data size and the traffic load using peers protocol since + all data/counters are pushed each time any of them is updated. + This data_type will exclude the usage of the legacy data_type 'gpt0' + on the same table. Using the 'gpt' array data_type, all 'gpt0' related + fetches and actions will apply to the first element of this array. + + - gpt0 : first General Purpose Tag. It is a positive 32-bit integer + integer which may be used for anything. Most of the time it will be used + to put a special tag on some entries, for instance to note that a + specific behavior was detected and must be known for future matches + + - conn_cnt : Connection Count. It is a positive 32-bit integer which counts + the absolute number of connections received from clients which matched + this entry. It does not mean the connections were accepted, just that + they were received. + + - conn_cur : Current Connections. It is a positive 32-bit integer which + stores the concurrent connection counts for the entry. It is incremented + once an incoming connection matches the entry, and decremented once the + connection leaves. That way it is possible to know at any time the exact + number of concurrent connections for an entry. + + - conn_rate(<period>) : frequency counter (takes 12 bytes). It takes an + integer parameter <period> which indicates in milliseconds the length + of the period over which the average is measured. It reports the average + incoming connection rate over that period, in connections per period. The + result is an integer which can be matched using ACLs. + + - sess_cnt : Session Count. It is a positive 32-bit integer which counts + the absolute number of sessions received from clients which matched this + entry. A session is a connection that was accepted by the layer 4 rules. + + - sess_rate(<period>) : frequency counter (takes 12 bytes). It takes an + integer parameter <period> which indicates in milliseconds the length + of the period over which the average is measured. It reports the average + incoming session rate over that period, in sessions per period. The + result is an integer which can be matched using ACLs. + + - http_req_cnt : HTTP request Count. It is a positive 32-bit integer which + counts the absolute number of HTTP requests received from clients which + matched this entry. It does not matter whether they are valid requests or + not. Note that this is different from sessions when keep-alive is used on + the client side. + + - http_req_rate(<period>) : frequency counter (takes 12 bytes). It takes an + integer parameter <period> which indicates in milliseconds the length + of the period over which the average is measured. It reports the average + HTTP request rate over that period, in requests per period. The result is + an integer which can be matched using ACLs. It does not matter whether + they are valid requests or not. Note that this is different from sessions + when keep-alive is used on the client side. + + - http_err_cnt : HTTP Error Count. It is a positive 32-bit integer which + counts the absolute number of HTTP requests errors induced by clients + which matched this entry. Errors are counted on invalid and truncated + requests, as well as on denied or tarpitted requests, and on failed + authentications. If the server responds with 4xx, then the request is + also counted as an error since it's an error triggered by the client + (e.g. vulnerability scan). + + - http_err_rate(<period>) : frequency counter (takes 12 bytes). It takes an + integer parameter <period> which indicates in milliseconds the length + of the period over which the average is measured. It reports the average + HTTP request error rate over that period, in requests per period (see + http_err_cnt above for what is accounted as an error). The result is an + integer which can be matched using ACLs. + + - http_fail_cnt : HTTP Failure Count. It is a positive 32-bit integer which + counts the absolute number of HTTP response failures induced by servers + which matched this entry. Errors are counted on invalid and truncated + responses, as well as any 5xx response other than 501 or 505. It aims at + being used combined with path or URI to detect service failures. + + - http_fail_rate(<period>) : frequency counter (takes 12 bytes). It takes + an integer parameter <period> which indicates in milliseconds the length + of the period over which the average is measured. It reports the average + HTTP response failure rate over that period, in requests per period (see + http_fail_cnt above for what is accounted as a failure). The result is an + integer which can be matched using ACLs. + + - bytes_in_cnt : client to server byte count. It is a positive 64-bit + integer which counts the cumulative number of bytes received from clients + which matched this entry. Headers are included in the count. This may be + used to limit abuse of upload features on photo or video servers. + + - bytes_in_rate(<period>) : frequency counter (takes 12 bytes). It takes an + integer parameter <period> which indicates in milliseconds the length + of the period over which the average is measured. It reports the average + incoming bytes rate over that period, in bytes per period. It may be used + to detect users which upload too much and too fast. Warning: with large + uploads, it is possible that the amount of uploaded data will be counted + once upon termination, thus causing spikes in the average transfer speed + instead of having a smooth one. This may partially be smoothed with + "option contstats" though this is not perfect yet. Use of byte_in_cnt is + recommended for better fairness. + + - bytes_out_cnt : server to client byte count. It is a positive 64-bit + integer which counts the cumulative number of bytes sent to clients which + matched this entry. Headers are included in the count. This may be used + to limit abuse of bots sucking the whole site. + + - bytes_out_rate(<period>) : frequency counter (takes 12 bytes). It takes + an integer parameter <period> which indicates in milliseconds the length + of the period over which the average is measured. It reports the average + outgoing bytes rate over that period, in bytes per period. It may be used + to detect users which download too much and too fast. Warning: with large + transfers, it is possible that the amount of transferred data will be + counted once upon termination, thus causing spikes in the average + transfer speed instead of having a smooth one. This may partially be + smoothed with "option contstats" though this is not perfect yet. Use of + byte_out_cnt is recommended for better fairness. + + There is only one stick-table per proxy. At the moment of writing this doc, + it does not seem useful to have multiple tables per proxy. If this happens + to be required, simply create a dummy backend with a stick-table in it and + reference it. + + It is important to understand that stickiness based on learning information + has some limitations, including the fact that all learned associations are + lost upon restart unless peers are properly configured to transfer such + information upon restart (recommended). In general it can be good as a + complement but not always as an exclusive stickiness. + + Last, memory requirements may be important when storing many data types. + Indeed, storing all indicators above at once in each entry requires 116 bytes + per entry, or 116 MB for a 1-million entries table. This is definitely not + something that can be ignored. + + Example: + # Keep track of counters of up to 1 million IP addresses over 5 minutes + # and store a general purpose counter and the average connection rate + # computed over a sliding window of 30 seconds. + stick-table type ip size 1m expire 5m store gpc0,conn_rate(30s) + + See also : "stick match", "stick on", "stick store-request", section 2.5 + about time format and section 7 about ACLs. + + +stick store-response <pattern> [table <table>] [{if | unless} <condition>] + Define a response pattern used to create an entry in a stickiness table + May be used in sections : defaults | frontend | listen | backend + no | no | yes | yes + + Arguments : + <pattern> is a sample expression rule as described in section 7.3. It + describes what elements of the response or connection will + be analyzed, extracted and stored in the table once a + server is selected. + + <table> is an optional stickiness table name. If unspecified, the same + backend's table is used. A stickiness table is declared using + the "stick-table" statement. + + <cond> is an optional storage condition. It makes it possible to store + certain criteria only when some conditions are met (or not met). + For instance, it could be used to store the SSL session ID only + when the response is a SSL server hello. + + Some protocols or applications require complex stickiness rules and cannot + always simply rely on cookies nor hashing. The "stick store-response" + statement describes a rule to decide what to extract from the response and + when to do it, in order to store it into a stickiness table for further + requests to match it using the "stick match" statement. Obviously the + extracted part must make sense and have a chance to be matched in a further + request. Storing an ID found in a header of a response makes sense. + See section 7 for a complete list of possible patterns and transformation + rules. + + The table has to be declared using the "stick-table" statement. It must be of + a type compatible with the pattern. By default it is the one which is present + in the same backend. It is possible to share a table with other backends by + referencing it using the "table" keyword. If another table is referenced, + the server's ID inside the backends are used. By default, all server IDs + start at 1 in each backend, so the server ordering is enough. But in case of + doubt, it is highly recommended to force server IDs using their "id" setting. + + It is possible to restrict the conditions where a "stick store-response" + statement will apply, using "if" or "unless" followed by a condition. This + condition will be evaluated while parsing the response, so any criteria can + be used. See section 7 for ACL based conditions. + + There is no limit on the number of "stick store-response" statements, but + there is a limit of 8 simultaneous stores per request or response. This + makes it possible to store up to 8 criteria, all extracted from either the + request or the response, regardless of the number of rules. Only the 8 first + ones which match will be kept. Using this, it is possible to feed multiple + tables at once in the hope to increase the chance to recognize a user on + another protocol or access method. Using multiple store-response rules with + the same table is possible and may be used to find the best criterion to rely + on, by arranging the rules by decreasing preference order. Only the first + extracted criterion for a given table will be stored. All subsequent store- + response rules referencing the same table will be skipped and their ACLs will + not be evaluated. However, even if a store-request rule references a table, a + store-response rule may also use the same table. This means that each table + may learn exactly one element from the request and one element from the + response at once. + + The table will contain the real server that processed the request. + + Example : + # Learn SSL session ID from both request and response and create affinity. + backend https + mode tcp + balance roundrobin + # maximum SSL session ID length is 32 bytes. + stick-table type binary len 32 size 30k expire 30m + + acl clienthello req.ssl_hello_type 1 + acl serverhello rep.ssl_hello_type 2 + + # use tcp content accepts to detects ssl client and server hello. + tcp-request inspect-delay 5s + tcp-request content accept if clienthello + + # no timeout on response inspect delay by default. + tcp-response content accept if serverhello + + # SSL session ID (SSLID) may be present on a client or server hello. + # Its length is coded on 1 byte at offset 43 and its value starts + # at offset 44. + + # Match and learn on request if client hello. + stick on req.payload_lv(43,1) if clienthello + + # Learn on response if server hello. + stick store-response resp.payload_lv(43,1) if serverhello + + server s1 192.168.1.1:443 + server s2 192.168.1.1:443 + + See also : "stick-table", "stick on", and section 7 about ACLs and pattern + extraction. + + +tcp-check comment <string> + Defines a comment for the following the tcp-check rule, reported in logs if + it fails. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + <string> is the comment message to add in logs if the following tcp-check + rule fails. + + It only works for connect, send and expect rules. It is useful to make + user-friendly error reporting. + + See also : "option tcp-check", "tcp-check connect", "tcp-check send" and + "tcp-check expect". + + +tcp-check connect [default] [port <expr>] [addr <ip>] [send-proxy] [via-socks4] + [ssl] [sni <sni>] [alpn <alpn>] [linger] + [proto <name>] [comment <msg>] + Opens a new connection + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + comment <msg> defines a message to report if the rule evaluation fails. + + default Use default options of the server line to do the health + checks. The server options are used only if not redefined. + + port <expr> if not set, check port or server port is used. + It tells HAProxy where to open the connection to. + <port> must be a valid TCP port source integer, from 1 to + 65535 or an sample-fetch expression. + + addr <ip> defines the IP address to do the health check. + + send-proxy send a PROXY protocol string + + via-socks4 enables outgoing health checks using upstream socks4 proxy. + + ssl opens a ciphered connection + + sni <sni> specifies the SNI to use to do health checks over SSL. + + alpn <alpn> defines which protocols to advertise with ALPN. The protocol + list consists in a comma-delimited list of protocol names, + for instance: "http/1.1,http/1.0" (without quotes). + If it is not set, the server ALPN is used. + + proto <name> forces the multiplexer's protocol to use for this connection. + It must be a TCP mux protocol and it must be usable on the + backend side. The list of available protocols is reported in + haproxy -vv. + + linger cleanly close the connection instead of using a single RST. + + When an application lies on more than a single TCP port or when HAProxy + load-balance many services in a single backend, it makes sense to probe all + the services individually before considering a server as operational. + + When there are no TCP port configured on the server line neither server port + directive, then the 'tcp-check connect port <port>' must be the first step + of the sequence. + + In a tcp-check ruleset a 'connect' is required, it is also mandatory to start + the ruleset with a 'connect' rule. Purpose is to ensure admin know what they + do. + + When a connect must start the ruleset, if may still be preceded by set-var, + unset-var or comment rules. + + Examples : + # check HTTP and HTTPs services on a server. + # first open port 80 thanks to server line port directive, then + # tcp-check opens port 443, ciphered and run a request on it: + option tcp-check + tcp-check connect + tcp-check send GET\ /\ HTTP/1.0\r\n + tcp-check send Host:\ haproxy.1wt.eu\r\n + tcp-check send \r\n + tcp-check expect rstring (2..|3..) + tcp-check connect port 443 ssl + tcp-check send GET\ /\ HTTP/1.0\r\n + tcp-check send Host:\ haproxy.1wt.eu\r\n + tcp-check send \r\n + tcp-check expect rstring (2..|3..) + server www 10.0.0.1 check port 80 + + # check both POP and IMAP from a single server: + option tcp-check + tcp-check connect port 110 linger + tcp-check expect string +OK\ POP3\ ready + tcp-check connect port 143 + tcp-check expect string *\ OK\ IMAP4\ ready + server mail 10.0.0.1 check + + See also : "option tcp-check", "tcp-check send", "tcp-check expect" + + +tcp-check expect [min-recv <int>] [comment <msg>] + [ok-status <st>] [error-status <st>] [tout-status <st>] + [on-success <fmt>] [on-error <fmt>] [status-code <expr>] + [!] <match> <pattern> + Specify data to be collected and analyzed during a generic health check + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + comment <msg> defines a message to report if the rule evaluation fails. + + min-recv is optional and can define the minimum amount of data required to + evaluate the current expect rule. If the number of received bytes + is under this limit, the check will wait for more data. This + option can be used to resolve some ambiguous matching rules or to + avoid executing costly regex matches on content known to be still + incomplete. If an exact string (string or binary) is used, the + minimum between the string length and this parameter is used. + This parameter is ignored if it is set to -1. If the expect rule + does not match, the check will wait for more data. If set to 0, + the evaluation result is always conclusive. + + <match> is a keyword indicating how to look for a specific pattern in the + response. The keyword may be one of "string", "rstring", "binary" or + "rbinary". + The keyword may be preceded by an exclamation mark ("!") to negate + the match. Spaces are allowed between the exclamation mark and the + keyword. See below for more details on the supported keywords. + + ok-status <st> is optional and can be used to set the check status if + the expect rule is successfully evaluated and if it is + the last rule in the tcp-check ruleset. "L7OK", "L7OKC", + "L6OK" and "L4OK" are supported : + - L7OK : check passed on layer 7 + - L7OKC : check conditionally passed on layer 7, set + server to NOLB state. + - L6OK : check passed on layer 6 + - L4OK : check passed on layer 4 + By default "L7OK" is used. + + error-status <st> is optional and can be used to set the check status if + an error occurred during the expect rule evaluation. + "L7OKC", "L7RSP", "L7STS", "L6RSP" and "L4CON" are + supported : + - L7OKC : check conditionally passed on layer 7, set + server to NOLB state. + - L7RSP : layer 7 invalid response - protocol error + - L7STS : layer 7 response error, for example HTTP 5xx + - L6RSP : layer 6 invalid response - protocol error + - L4CON : layer 1-4 connection problem + By default "L7RSP" is used. + + tout-status <st> is optional and can be used to set the check status if + a timeout occurred during the expect rule evaluation. + "L7TOUT", "L6TOUT", and "L4TOUT" are supported : + - L7TOUT : layer 7 (HTTP/SMTP) timeout + - L6TOUT : layer 6 (SSL) timeout + - L4TOUT : layer 1-4 timeout + By default "L7TOUT" is used. + + on-success <fmt> is optional and can be used to customize the + informational message reported in logs if the expect + rule is successfully evaluated and if it is the last rule + in the tcp-check ruleset. <fmt> is a log-format string. + + on-error <fmt> is optional and can be used to customize the + informational message reported in logs if an error + occurred during the expect rule evaluation. <fmt> is a + log-format string. + + status-code <expr> is optional and can be used to set the check status code + reported in logs, on success or on error. <expr> is a + standard HAProxy expression formed by a sample-fetch + followed by some converters. + + <pattern> is the pattern to look for. It may be a string or a regular + expression. If the pattern contains spaces, they must be escaped + with the usual backslash ('\'). + If the match is set to binary, then the pattern must be passed as + a series of hexadecimal digits in an even number. Each sequence of + two digits will represent a byte. The hexadecimal digits may be + used upper or lower case. + + The available matches are intentionally similar to their http-check cousins : + + string <string> : test the exact string matches in the response buffer. + A health check response will be considered valid if the + response's buffer contains this exact string. If the + "string" keyword is prefixed with "!", then the response + will be considered invalid if the body contains this + string. This can be used to look for a mandatory pattern + in a protocol response, or to detect a failure when a + specific error appears in a protocol banner. + + rstring <regex> : test a regular expression on the response buffer. + A health check response will be considered valid if the + response's buffer matches this expression. If the + "rstring" keyword is prefixed with "!", then the response + will be considered invalid if the body matches the + expression. + + string-lf <fmt> : test a log-format string match in the response's buffer. + A health check response will be considered valid if the + response's buffer contains the string resulting of the + evaluation of <fmt>, which follows the log-format rules. + If prefixed with "!", then the response will be + considered invalid if the buffer contains the string. + + binary <hexstring> : test the exact string in its hexadecimal form matches + in the response buffer. A health check response will + be considered valid if the response's buffer contains + this exact hexadecimal string. + Purpose is to match data on binary protocols. + + rbinary <regex> : test a regular expression on the response buffer, like + "rstring". However, the response buffer is transformed + into its hexadecimal form, including NUL-bytes. This + allows using all regex engines to match any binary + content. The hexadecimal transformation takes twice the + size of the original response. As such, the expected + pattern should work on at-most half the response buffer + size. + + binary-lf <hexfmt> : test a log-format string in its hexadecimal form + match in the response's buffer. A health check response + will be considered valid if the response's buffer + contains the hexadecimal string resulting of the + evaluation of <fmt>, which follows the log-format + rules. If prefixed with "!", then the response will be + considered invalid if the buffer contains the + hexadecimal string. The hexadecimal string is converted + in a binary string before matching the response's + buffer. + + It is important to note that the responses will be limited to a certain size + defined by the global "tune.bufsize" option, which defaults to 16384 bytes. + Thus, too large responses may not contain the mandatory pattern when using + "string", "rstring" or binary. If a large response is absolutely required, it + is possible to change the default max size by setting the global variable. + However, it is worth keeping in mind that parsing very large responses can + waste some CPU cycles, especially when regular expressions are used, and that + it is always better to focus the checks on smaller resources. Also, in its + current state, the check will not find any string nor regex past a null + character in the response. Similarly it is not possible to request matching + the null character. + + Examples : + # perform a POP check + option tcp-check + tcp-check expect string +OK\ POP3\ ready + + # perform an IMAP check + option tcp-check + tcp-check expect string *\ OK\ IMAP4\ ready + + # look for the redis master server + option tcp-check + tcp-check send PING\r\n + tcp-check expect string +PONG + tcp-check send info\ replication\r\n + tcp-check expect string role:master + tcp-check send QUIT\r\n + tcp-check expect string +OK + + + See also : "option tcp-check", "tcp-check connect", "tcp-check send", + "tcp-check send-binary", "http-check expect", tune.bufsize + + +tcp-check send <data> [comment <msg>] +tcp-check send-lf <fmt> [comment <msg>] + Specify a string or a log-format string to be sent as a question during a + generic health check + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + comment <msg> defines a message to report if the rule evaluation fails. + + <data> is the string that will be sent during a generic health + check session. + + <fmt> is the log-format string that will be sent, once evaluated, + during a generic health check session. + + Examples : + # look for the redis master server + option tcp-check + tcp-check send info\ replication\r\n + tcp-check expect string role:master + + See also : "option tcp-check", "tcp-check connect", "tcp-check expect", + "tcp-check send-binary", tune.bufsize + + +tcp-check send-binary <hexstring> [comment <msg>] +tcp-check send-binary-lf <hexfmt> [comment <msg>] + Specify an hex digits string or an hex digits log-format string to be sent as + a binary question during a raw tcp health check + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + comment <msg> defines a message to report if the rule evaluation fails. + + <hexstring> is the hexadecimal string that will be send, once converted + to binary, during a generic health check session. + + <hexfmt> is the hexadecimal log-format string that will be send, once + evaluated and converted to binary, during a generic health + check session. + + Examples : + # redis check in binary + option tcp-check + tcp-check send-binary 50494e470d0a # PING\r\n + tcp-check expect binary 2b504F4e47 # +PONG + + + See also : "option tcp-check", "tcp-check connect", "tcp-check expect", + "tcp-check send", tune.bufsize + + +tcp-check set-var(<var-name>[,<cond>...]) <expr> +tcp-check set-var-fmt(<var-name>[,<cond>...]) <fmt> + This operation sets the content of a variable. The variable is declared inline. + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + <var-name> The name of the variable starts with an indication about its + scope. The scopes allowed for tcp-check are: + "proc" : the variable is shared with the whole process. + "sess" : the variable is shared with the tcp-check session. + "check": the variable is declared for the lifetime of the tcp-check. + This prefix is followed by a name. The separator is a '.'. + The name may only contain characters 'a-z', 'A-Z', '0-9', '.', + and '-'. + + <cond> A set of conditions that must all be true for the variable to + actually be set (such as "ifnotempty", "ifgt" ...). See the + set-var converter's description for a full list of possible + conditions. + + <expr> Is a sample-fetch expression potentially followed by converters. + + <fmt> This is the value expressed using log-format rules (see Custom + Log Format in section 8.2.4). + + Examples : + tcp-check set-var(check.port) int(1234) + tcp-check set-var-fmt(check.name) "%H" + + +tcp-check unset-var(<var-name>) + Free a reference to a variable within its scope. + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + + Arguments : + <var-name> The name of the variable starts with an indication about its + scope. The scopes allowed for tcp-check are: + "proc" : the variable is shared with the whole process. + "sess" : the variable is shared with the tcp-check session. + "check": the variable is declared for the lifetime of the tcp-check. + This prefix is followed by a name. The separator is a '.'. + The name may only contain characters 'a-z', 'A-Z', '0-9', '.', + and '-'. + + Examples : + tcp-check unset-var(check.port) + + +tcp-request connection <action> <options...> [ { if | unless } <condition> ] + Perform an action on an incoming connection depending on a layer 4 condition + May be used in sections : defaults | frontend | listen | backend + yes(!) | yes | yes | no + Arguments : + <action> defines the action to perform if the condition applies. See + below. + + <condition> is a standard layer4-only ACL-based condition (see section 7). + + Immediately after acceptance of a new incoming connection, it is possible to + evaluate some conditions to decide whether this connection must be accepted + or dropped or have its counters tracked. Those conditions cannot make use of + any data contents because the connection has not been read from yet, and the + buffers are not yet allocated. This is used to selectively and very quickly + accept or drop connections from various sources with a very low overhead. If + some contents need to be inspected in order to take the decision, the + "tcp-request content" statements must be used instead. + + The "tcp-request connection" rules are evaluated in their exact declaration + order. If no rule matches or if there is no rule, the default action is to + accept the incoming connection. There is no specific limit to the number of + rules which may be inserted. Any rule may optionally be followed by an + ACL-based condition, in which case it will only be evaluated if the condition + is true. + + The first keyword is the rule's action. Several types of actions are + supported: + - accept + - expect-netscaler-cip layer4 + - expect-proxy layer4 + - reject + - sc-inc-gpc(<idx>,<sc-id>) + - sc-inc-gpc0(<sc-id>) + - sc-inc-gpc1(<sc-id>) + - sc-set-gpt(<idx>,<sc-id>) { <int> | <expr> } + - sc-set-gpt0(<sc-id>) { <int> | <expr> } + - set-dst <expr> + - set-dst-port <expr> + - set-mark <mark> + - set-src <expr> + - set-src-port <expr> + - set-tos <tos> + - set-var(<var-name>[,<cond>...]) <expr> + - set-var-fmt(<var-name>[,<cond>...]) <fmt> + - silent-drop + - track-sc0 <key> [table <table>] + - track-sc1 <key> [table <table>] + - track-sc2 <key> [table <table>] + - unset-var(<var-name>) + + The supported actions are described below. + + There is no limit to the number of "tcp-request connection" statements per + instance. + + This directive is only available from named defaults sections, not anonymous + ones. Rules defined in the defaults section are evaluated before ones in the + associated proxy section. To avoid ambiguities, in this case the same + defaults section cannot be used by proxies with the frontend capability and + by proxies with the backend capability. It means a listen section cannot use + a defaults section defining such rules. + + Note that the "if/unless" condition is optional. If no condition is set on + the action, it is simply performed unconditionally. That can be useful for + "track-sc*" actions as well as for changing the default action to a reject. + + Example: accept all connections from white-listed hosts, reject too fast + connection without counting them, and track accepted connections. + This results in connection rate being capped from abusive sources. + + tcp-request connection accept if { src -f /etc/haproxy/whitelist.lst } + tcp-request connection reject if { src_conn_rate gt 10 } + tcp-request connection track-sc0 src + + Example: accept all connections from white-listed hosts, count all other + connections and reject too fast ones. This results in abusive ones + being blocked as long as they don't slow down. + + tcp-request connection accept if { src -f /etc/haproxy/whitelist.lst } + tcp-request connection track-sc0 src + tcp-request connection reject if { sc0_conn_rate gt 10 } + + Example: enable the PROXY protocol for traffic coming from all known proxies. + + tcp-request connection expect-proxy layer4 if { src -f proxies.lst } + + See section 7 about ACL usage. + + See also : "tcp-request session", "tcp-request content", "stick-table" + +tcp-request connection accept [ { if | unless } <condition> ] + + This is used to accept the connection. No further "tcp-request connection" + rules are evaluated. + +tcp-request connection expect-netscaler-cip layer4 + [ { if | unless } <condition> ] + + This configures the client-facing connection to receive a NetScaler Client IP + insertion protocol header before any byte is read from the socket. This is + equivalent to having the "accept-netscaler-cip" keyword on the "bind" line, + except that using the TCP rule allows the PROXY protocol to be accepted only + for certain IP address ranges using an ACL. This is convenient when multiple + layers of load balancers are passed through by traffic coming from public + hosts. + +tcp-request connection expect-proxy layer4 [ { if | unless } <condition> ] + + This configures the client-facing connection to receive a PROXY protocol + header before any byte is read from the socket. This is equivalent to having + the "accept-proxy" keyword on the "bind" line, except that using the TCP rule + allows the PROXY protocol to be accepted only for certain IP address ranges + using an ACL. This is convenient when multiple layers of load balancers are + passed through by traffic coming from public hosts. + +tcp-request connection reject [ { if | unless } <condition> ] + + This is used to reject the connection. No further "tcp-request connection" + rules are evaluated. Rejected connections do not even become a session, which + is why they are accounted separately for in the stats, as "denied + connections". They are not considered for the session rate-limit and are not + logged either. The reason is that these rules should only be used to filter + extremely high connection rates such as the ones encountered during a massive + DDoS attack. Under these extreme conditions, the simple action of logging + each event would make the system collapse and would considerably lower the + filtering capacity. If logging is absolutely desired, then "tcp-request + content" rules should be used instead, as "tcp-request session" rules will + not log either. + +tcp-request connection sc-inc-gpc(<idx>,<sc-id>) [ { if | unless } <condition> ] +tcp-request connection sc-inc-gpc0(<sc-id>) [ { if | unless } <condition> ] +tcp-request connection sc-inc-gpc1(<sc-id>) [ { if | unless } <condition> ] + + These actions increment the General Purppose Counters according to the sticky + counter designated by <sc-id>. Please refer to "http-request sc-inc-gpc", + "http-request sc-inc-gpc0" and "http-request sc-inc-gpc1" for a complete + description. + +tcp-request connection sc-set-gpt(<idx>,<sc-id>) { <int> | <expr> } + [ { if | unless } <condition> ] +tcp-request connection sc-set-gpt0(<sc-id>) { <int> | <expr> } + [ { if | unless } <condition> ] + + These actions set the 32-bit unsigned General Purpose Tags according to the + sticky counter designated by <sc-id>. Please refer to "http-request + sc-inc-gpt" and "http-request sc-inc-gpt0" for a complete description. + +tcp-request connection set-dst <expr> [ { if | unless } <condition> ] +tcp-request connection set-dst-port <expr> [ { if | unless } <condition> ] + + These actions are used to set the destination IP/Port address to the value of + specified expression. Please refer to "http-request set-dst" and + "http-request set-dst-port" for a complete description. + +tcp-request connection set-mark <mark> [ { if | unless } <condition> ] + + This action is used to set the Netfilter/IPFW MARK in all packets sent to the + client to the value passed in <mark> on platforms which support it. Please + refer to "http-request set-mark" for a complete description. + +tcp-request connection set-src <expr> [ { if | unless } <condition> ] +tcp-request connection set-src-port <expr> [ { if | unless } <condition> ] + + These actions are used to set the source IP/Port address to the value of + specified expression. Please refer to "http-request set-src" and + "http-request set-src-port" for a complete description. + +tcp-request connection set-tos <tos> [ { if | unless } <condition> ] + + This is used to set the TOS or DSCP field value of packets sent to the client + to the value passed in <tos> on platforms which support this. Please refer to + "http-request set-tos" for a complete description. + +tcp-request connection set-var(<var-name>[,<cond>...]) <expr> [ { if | unless } <condition> ] +tcp-request connection set-var-fmt(<var-name>[,<cond>...]) <fmt> [ { if | unless } <condition> ] + + This is used to set the contents of a variable. The variable is declared + inline. "tcp-request connection" can set variables in the "proc" and "sess" + scopes. Please refer to "http-request set-var" and "http-request set-var-fmt" + for a complete description. + +tcp-request connection silent-drop [ { if | unless } <condition> ] + + This stops the evaluation of the rules and makes the client-facing connection + suddenly disappear using a system-dependent way that tries to prevent the + client from being notified. Please refer to "http-request silent-drop" for a + complete description. + +tcp-request connection track-sc0 <key> [table <table>] [ { if | unless } <condition> ] +tcp-request connection track-sc1 <key> [table <table>] [ { if | unless } <condition> ] +tcp-request connection track-sc2 <key> [table <table>] [ { if | unless } <condition> ] + + This enables tracking of sticky counters from current connection. Please + refer to "http-request track-sc0", "http-request track-sc1" and "http-request + track-sc2" for a complete description. + +tcp-request connection unset-var(<var-name>) [ { if | unless } <condition> ] + + This is used to unset a variable. Please refer to "http-request set-var" for + details about variables. + + +tcp-request content <action> [{if | unless} <condition>] + Perform an action on a new session depending on a layer 4-7 condition + May be used in sections : defaults | frontend | listen | backend + yes(!) | yes | yes | yes + Arguments : + <action> defines the action to perform if the condition applies. See + below. + + <condition> is a standard layer 4-7 ACL-based condition (see section 7). + + A request's contents can be analyzed at an early stage of request processing + called "TCP content inspection". During this stage, ACL-based rules are + evaluated every time the request contents are updated, until either an + "accept", a "reject" or a "switch-mode" rule matches, or the TCP request + inspection delay expires with no matching rule. + + The first difference between these rules and "tcp-request connection" rules + is that "tcp-request content" rules can make use of contents to take a + decision. Most often, these decisions will consider a protocol recognition or + validity. The second difference is that content-based rules can be used in + both frontends and backends. In case of HTTP keep-alive with the client, all + tcp-request content rules are evaluated again, so HAProxy keeps a record of + what sticky counters were assigned by a "tcp-request connection" versus a + "tcp-request content" rule, and flushes all the content-related ones after + processing an HTTP request, so that they may be evaluated again by the rules + being evaluated again for the next request. This is of particular importance + when the rule tracks some L7 information or when it is conditioned by an + L7-based ACL, since tracking may change between requests. + + Content-based rules are evaluated in their exact declaration order. If no + rule matches or if there is no rule, the default action is to accept the + contents. There is no specific limit to the number of rules which may be + inserted. + + The first keyword is the rule's action. Several types of actions are + supported: + - accept + - capture <sample> len <length> + - do-resolve(<var>,<resolvers>,[ipv4,ipv6]) <expr> + - reject + - sc-inc-gpc(<idx>,<sc-id>) + - sc-inc-gpc0(<sc-id>) + - sc-inc-gpc1(<sc-id>) + - sc-set-gpt(<idx>,<sc-id>) { <int> | <expr> } + - sc-set-gpt0(<sc-id>) { <int> | <expr> } + - send-spoe-group <engine-name> <group-name> + - set-dst <expr> + - set-dst-port <expr> + - set-log-level <level> + - set-mark <mark> + - set-nice <nice> + - set-priority-class <expr> + - set-priority-offset <expr> + - set-src <expr> + - set-src-port <expr> + - set-tos <tos> + - set-var(<var-name>[,<cond>...]) <expr> + - set-var-fmt(<var-name>[,<cond>...]) <fmt> + - silent-drop + - switch-mode http [ proto <name> ] + - track-sc0 <key> [table <table>] + - track-sc1 <key> [table <table>] + - track-sc2 <key> [table <table>] + - unset-var(<var-name>) + - use-service <service-name> + + The supported actions are described below. + + While there is nothing mandatory about it, it is recommended to use the + track-sc0 in "tcp-request connection" rules, track-sc1 for "tcp-request + content" rules in the frontend, and track-sc2 for "tcp-request content" + rules in the backend, because that makes the configuration more readable + and easier to troubleshoot, but this is just a guideline and all counters + may be used everywhere. + + This directive is only available from named defaults sections, not anonymous + ones. Rules defined in the defaults section are evaluated before ones in the + associated proxy section. To avoid ambiguities, in this case the same + defaults section cannot be used by proxies with the frontend capability and + by proxies with the backend capability. It means a listen section cannot use + a defaults section defining such rules. + + Note that the "if/unless" condition is optional. If no condition is set on + the action, it is simply performed unconditionally. That can be useful for + "track-sc*" actions as well as for changing the default action to a reject. + + Note also that it is recommended to use a "tcp-request session" rule to track + information that does *not* depend on Layer 7 contents, especially for HTTP + frontends. Some HTTP processing are performed at the session level and may + lead to an early rejection of the requests. Thus, the tracking at the content + level may be disturbed in such case. A warning is emitted during startup to + prevent, as far as possible, such unreliable usage. + + It is perfectly possible to match layer 7 contents with "tcp-request content" + rules from a TCP proxy, since HTTP-specific ACL matches are able to + preliminarily parse the contents of a buffer before extracting the required + data. If the buffered contents do not parse as a valid HTTP message, then the + ACL does not match. The parser which is involved there is exactly the same + as for all other HTTP processing, so there is no risk of parsing something + differently. In an HTTP frontend or an HTTP backend, it is guaranteed that + HTTP contents will always be immediately present when the rule is evaluated + first because the HTTP parsing is performed in the early stages of the + connection processing, at the session level. But for such proxies, using + "http-request" rules is much more natural and recommended. + + Tracking layer7 information is also possible provided that the information + are present when the rule is processed. The rule processing engine is able to + wait until the inspect delay expires when the data to be tracked is not yet + available. + + Example: + tcp-request content use-service lua.deny if { src -f /etc/haproxy/blacklist.lst } + + Example: + + tcp-request content set-var(sess.my_var) src + tcp-request content set-var-fmt(sess.from) %[src]:%[src_port] + tcp-request content unset-var(sess.my_var2) + + Example: + # Accept HTTP requests containing a Host header saying "example.com" + # and reject everything else. (Only works for HTTP/1 connections) + acl is_host_com hdr(Host) -i example.com + tcp-request inspect-delay 30s + tcp-request content accept if is_host_com + tcp-request content reject + + # Accept HTTP requests containing a Host header saying "example.com" + # and reject everything else. (works for HTTP/1 and HTTP/2 connections) + acl is_host_com hdr(Host) -i example.com + tcp-request inspect-delay 5s + tcp-request switch-mode http if HTTP + tcp-request reject # non-HTTP traffic is implicit here + ... + http-request reject unless is_host_com + + Example: + # reject SMTP connection if client speaks first + tcp-request inspect-delay 30s + acl content_present req.len gt 0 + tcp-request content reject if content_present + + # Forward HTTPS connection only if client speaks + tcp-request inspect-delay 30s + acl content_present req.len gt 0 + tcp-request content accept if content_present + tcp-request content reject + + Example: + # Track the last IP(stick-table type string) from X-Forwarded-For + tcp-request inspect-delay 10s + tcp-request content track-sc0 hdr(x-forwarded-for,-1) + # Or track the last IP(stick-table type ip|ipv6) from X-Forwarded-For + tcp-request content track-sc0 req.hdr_ip(x-forwarded-for,-1) + + Example: + # track request counts per "base" (concatenation of Host+URL) + tcp-request inspect-delay 10s + tcp-request content track-sc0 base table req-rate + + Example: track per-frontend and per-backend counters, block abusers at the + frontend when the backend detects abuse(and marks gpc0). + + frontend http + # Use General Purpose Counter 0 in SC0 as a global abuse counter + # protecting all our sites + stick-table type ip size 1m expire 5m store gpc0 + tcp-request connection track-sc0 src + tcp-request connection reject if { sc0_get_gpc0 gt 0 } + ... + use_backend http_dynamic if { path_end .php } + + backend http_dynamic + # if a source makes too fast requests to this dynamic site (tracked + # by SC1), block it globally in the frontend. + stick-table type ip size 1m expire 5m store http_req_rate(10s) + acl click_too_fast sc1_http_req_rate gt 10 + acl mark_as_abuser sc0_inc_gpc0(http) gt 0 + tcp-request content track-sc1 src + tcp-request content reject if click_too_fast mark_as_abuser + + See section 7 about ACL usage. + + See also : "tcp-request connection", "tcp-request session", + "tcp-request inspect-delay", and "http-request". + +tcp-request content accept [ { if | unless } <condition> ] + + This is used to accept the connection. No further "tcp-request content" + rules are evaluated for the current section. + +tcp-request content capture <sample> len <length> + [ { if | unless } <condition> ] + + This captures sample expression <sample> from the request buffer, and + converts it to a string of at most <len> characters. The resulting string is + stored into the next request "capture" slot, so it will possibly appear next + to some captured HTTP headers. It will then automatically appear in the logs, + and it will be possible to extract it using sample fetch rules to feed it + into headers or anything. The length should be limited given that this size + will be allocated for each capture during the whole session life. Please + check section 7.3 (Fetching samples) and "capture request header" for more + information. + +tcp-request content do-resolve(<var>,<resolvers>,[ipv4,ipv6]) <expr> + + This action performs a DNS resolution of the output of <expr> and stores the + result in the variable <var>. Please refer to "http-request do-resolve" for a + complete description. + +tcp-request content reject [ { if | unless } <condition> ] + + This is used to reject the connection. No further "tcp-request content" rules + are evaluated. + +tcp-request content sc-inc-gpc(<idx>,<sc-id>) [ { if | unless } <condition> ] +tcp-request content sc-inc-gpc0(<sc-id>) [ { if | unless } <condition> ] +tcp-request content sc-inc-gpc1(<sc-id>) [ { if | unless } <condition> ] + + These actions increment the General Purppose Counters according to the sticky + counter designated by <sc-id>. Please refer to "http-request sc-inc-gpc", + "http-request sc-inc-gpc0" and "http-request sc-inc-gpc1" for a complete + description. + +tcp-request content sc-set-gpt(<idx>,<sc-id>) { <int> | <expr> } + [ { if | unless } <condition> ] +tcp-request content sc-set-gpt0(<sc-id>) { <int> | <expr> } + [ { if | unless } <condition> ] + + These actions set the 32-bit unsigned General Purpose Tags according to the + sticky counter designated by <sc-id>. Please refer to "http-request + sc-inc-gpt" and "http-request sc-inc-gpt0" for a complete description. + +tcp-request content send-spoe-group <engine-name> <group-name> + [ { if | unless } <condition> ] + + Thaction is is used to trigger sending of a group of SPOE messages. Please + refer to "http-request send-spoe-group" for a complete description. + +tcp-request content set-dst <expr> [ { if | unless } <condition> ] +tcp-request content set-dst-port <expr> [ { if | unless } <condition> ] + + These actions are used to set the destination IP/Port address to the value of + specified expression. Please refer to "http-request set-dst" and + "http-request set-dst-port" for a complete description. + +tcp-request content set-log-level <level> [ { if | unless } <condition> ] + + This action is used to set the log level of the current session. Please refer + to "http-request set-log-level". for a complete description. + +tcp-request content set-mark <mark> [ { if | unless } <condition> ] + + This action is used to set the Netfilter/IPFW MARK in all packets sent to the + client to the value passed in <mark> on platforms which support it. Please + refer to "http-request set-mark" for a complete description. + +tcp-request content set-nice <nice> [ { if | unless } <condition> ] + + This sets the "nice" factor of the current request being processed. Please + refer to "http-request set-nice" for a complete description. + +tcp-request content set-priority-class <expr> [ { if | unless } <condition> ] + + This is used to set the queue priority class of the current request. Please + refer to "http-request set-priority-class" for a complete description. + +tcp-request content set-priority-offset <expr> [ { if | unless } <condition> ] + + This is used to set the queue priority timestamp offset of the current + request. Please refer to "http-request set-priority-offset" for a complete + description. + +tcp-request content set-src <expr> [ { if | unless } <condition> ] +tcp-request content set-src-port <expr> [ { if | unless } <condition> ] + + These actions are used to set the source IP/Port address to the value of + specified expression. Please refer to "http-request set-src" and + "http-request set-src-port" for a complete description. + +tcp-request content set-tos <tos> [ { if | unless } <condition> ] + + This is used to set the TOS or DSCP field value of packets sent to the client + to the value passed in <tos> on platforms which support this. Please refer to + "http-request set-tos" for a complete description. + +tcp-request content set-var(<var-name>[,<cond>...]) <expr> [ { if | unless } <condition> ] +tcp-request content set-var-fmt(<var-name>[,<cond>...]) <fmt> [ { if | unless } <condition> ] + + This is used to set the contents of a variable. The variable is declared + inline. Please refer to "http-request set-var" and "http-request set-var-fmt" + for a complete description. + +tcp-request content silent-drop [ { if | unless } <condition> ] + + This stops the evaluation of the rules and makes the client-facing connection + suddenly disappear using a system-dependent way that tries to prevent the + client from being notified. Please refer to "http-request silent-drop" for a + complete description. + +tcp-request content switch-mode http [ proto <name> ] + [ { if | unless } <condition> ] + + This action is used to perform a connection upgrade. Only HTTP upgrades are + supported for now. The protocol may optionally be specified. This action is + only available for a proxy with the frontend capability. The connection + upgrade is immediately performed, following "tcp-request content" rules are + not evaluated. This upgrade method should be preferred to the implicit one + consisting to rely on the backend mode. When used, it is possible to set HTTP + directives in a frontend without any warning. These directives will be + conditionally evaluated if the HTTP upgrade is performed. However, an HTTP + backend must still be selected. It remains unsupported to route an HTTP + connection (upgraded or not) to a TCP server. + + See section 4 about Proxies for more details on HTTP upgrades. + +tcp-request content track-sc0 <key> [table <table>] [ { if | unless } <condition> ] +tcp-request content track-sc1 <key> [table <table>] [ { if | unless } <condition> ] +tcp-request content track-sc2 <key> [table <table>] [ { if | unless } <condition> ] + + This enables tracking of sticky counters from current connection. Please + refer to "http-request track-sc0", "http-request track-sc1" and "http-request + track-sc2" for a complete description. + +tcp-request content unset-var(<var-name>) [ { if | unless } <condition> ] + + This is used to unset a variable. Please refer to "http-request set-var" for + details about variables. + +tcp-request content use-service <service-name> [ { if | unless } <condition> ] + + This action is used to executes a TCP service which will reply to the request + and stop the evaluation of the rules. This service may choose to reply by + sending any valid response or it may immediately close the connection without + sending anything. Outside natives services, it is possible to write your own + services in Lua. No further "tcp-request content" rules are evaluated. + + +tcp-request inspect-delay <timeout> + Set the maximum allowed time to wait for data during content inspection + May be used in sections : defaults | frontend | listen | backend + yes(!) | yes | yes | yes + Arguments : + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + People using HAProxy primarily as a TCP relay are often worried about the + risk of passing any type of protocol to a server without any analysis. In + order to be able to analyze the request contents, we must first withhold + the data then analyze them. This statement simply enables withholding of + data for at most the specified amount of time. + + TCP content inspection applies very early when a connection reaches a + frontend, then very early when the connection is forwarded to a backend. This + means that a connection may experience a first delay in the frontend and a + second delay in the backend if both have tcp-request rules. + + Note that when performing content inspection, HAProxy will evaluate the whole + rules for every new chunk which gets in, taking into account the fact that + those data are partial. If no rule matches before the aforementioned delay, + a last check is performed upon expiration, this time considering that the + contents are definitive. If no delay is set, HAProxy will not wait at all + and will immediately apply a verdict based on the available information. + Obviously this is unlikely to be very useful and might even be racy, so such + setups are not recommended. + + As soon as a rule matches, the request is released and continues as usual. If + the timeout is reached and no rule matches, the default policy will be to let + it pass through unaffected. + + For most protocols, it is enough to set it to a few seconds, as most clients + send the full request immediately upon connection. Add 3 or more seconds to + cover TCP retransmits but that's all. For some protocols, it may make sense + to use large values, for instance to ensure that the client never talks + before the server (e.g. SMTP), or to wait for a client to talk before passing + data to the server (e.g. SSL). Note that the client timeout must cover at + least the inspection delay, otherwise it will expire first. If the client + closes the connection or if the buffer is full, the delay immediately expires + since the contents will not be able to change anymore. + + This directive is only available from named defaults sections, not anonymous + ones. Proxies inherit this value from their defaults section. + + See also : "tcp-request content accept", "tcp-request content reject", + "timeout client". + + +tcp-request session <action> [{if | unless} <condition>] + Perform an action on a validated session depending on a layer 5 condition + May be used in sections : defaults | frontend | listen | backend + yes(!) | yes | yes | no + Arguments : + <action> defines the action to perform if the condition applies. See + below. + + <condition> is a standard layer5-only ACL-based condition (see section 7). + + Once a session is validated, (i.e. after all handshakes have been completed), + it is possible to evaluate some conditions to decide whether this session + must be accepted or dropped or have its counters tracked. Those conditions + cannot make use of any data contents because no buffers are allocated yet and + the processing cannot wait at this stage. The main use case is to copy some + early information into variables (since variables are accessible in the + session), or to keep track of some information collected after the handshake, + such as SSL-level elements (SNI, ciphers, client cert's CN) or information + from the PROXY protocol header (e.g. track a source forwarded this way). The + extracted information can thus be copied to a variable or tracked using + "track-sc" rules. Of course it is also possible to decide to accept/reject as + with other rulesets. Most operations performed here could also be performed + in "tcp-request content" rules, except that in HTTP these rules are evaluated + for each new request, and that might not always be acceptable. For example a + rule might increment a counter on each evaluation. It would also be possible + that a country is resolved by geolocation from the source IP address, + assigned to a session-wide variable, then the source address rewritten from + an HTTP header for all requests. If some contents need to be inspected in + order to take the decision, the "tcp-request content" statements must be used + instead. + + The "tcp-request session" rules are evaluated in their exact declaration + order. If no rule matches or if there is no rule, the default action is to + accept the incoming session. There is no specific limit to the number of + rules which may be inserted. + + The first keyword is the rule's action. Several types of actions are + supported: + - accept + - reject + - sc-inc-gpc(<idx>,<sc-id>) + - sc-inc-gpc0(<sc-id>) + - sc-inc-gpc1(<sc-id>) + - sc-set-gpt(<idx>,<sc-id>) { <int> | <expr> } + - sc-set-gpt0(<sc-id>) { <int> | <expr> } + - set-dst <expr> + - set-dst-port <expr> + - set-mark <mark> + - set-src <expr> + - set-src-port <expr> + - set-tos <tos> + - set-var(<var-name>[,<cond>...]) <expr> + - set-var-fmt(<var-name>[,<cond>...]) <fmt> + - silent-drop + - track-sc0 <key> [table <table>] + - track-sc1 <key> [table <table>] + - track-sc2 <key> [table <table>] + - unset-var(<var-name>) + + The supported actions are described below. + + This directive is only available from named defaults sections, not anonymous + ones. Rules defined in the defaults section are evaluated before ones in the + associated proxy section. To avoid ambiguities, in this case the same + defaults section cannot be used by proxies with the frontend capability and + by proxies with the backend capability. It means a listen section cannot use + a defaults section defining such rules. + + Note that the "if/unless" condition is optional. If no condition is set on + the action, it is simply performed unconditionally. That can be useful for + "track-sc*" actions as well as for changing the default action to a reject. + + Example: track the original source address by default, or the one advertised + in the PROXY protocol header for connection coming from the local + proxies. The first connection-level rule enables receipt of the + PROXY protocol for these ones, the second rule tracks whatever + address we decide to keep after optional decoding. + + tcp-request connection expect-proxy layer4 if { src -f proxies.lst } + tcp-request session track-sc0 src + + Example: accept all sessions from white-listed hosts, reject too fast + sessions without counting them, and track accepted sessions. + This results in session rate being capped from abusive sources. + + tcp-request session accept if { src -f /etc/haproxy/whitelist.lst } + tcp-request session reject if { src_sess_rate gt 10 } + tcp-request session track-sc0 src + + Example: accept all sessions from white-listed hosts, count all other + sessions and reject too fast ones. This results in abusive ones + being blocked as long as they don't slow down. + + tcp-request session accept if { src -f /etc/haproxy/whitelist.lst } + tcp-request session track-sc0 src + tcp-request session reject if { sc0_sess_rate gt 10 } + + See section 7 about ACL usage. + + See also : "tcp-request connection", "tcp-request content", "stick-table" + +tcp-request session accept [ { if | unless } <condition> ] + + This is used to accept the connection. No further "tcp-request session" + rules are evaluated. + +tcp-request session reject [ { if | unless } <condition> ] + + This is used to reject the connection. No further "tcp-request session" rules + are evaluated. + +tcp-request session sc-inc-gpc(<idx>,<sc-id>) [ { if | unless } <condition> ] +tcp-request session sc-inc-gpc0(<sc-id>) [ { if | unless } <condition> ] +tcp-request session sc-inc-gpc1(<sc-id>) [ { if | unless } <condition> ] + + These actions increment the General Purppose Counters according to the sticky + counter designated by <sc-id>. Please refer to "http-request sc-inc-gpc", + "http-request sc-inc-gpc0" and "http-request sc-inc-gpc1" for a complete + description. + +tcp-request session sc-set-gpt(<idx>,<sc-id>) { <int> | <expr> } + [ { if | unless } <condition> ] +tcp-request session sc-set-gpt0(<sc-id>) { <int> | <expr> } + [ { if | unless } <condition> ] + + These actions set the 32-bit unsigned General Purpose Tags according to the + sticky counter designated by <sc-id>. Please refer to "tcp-request connection + sc-inc-gpt" and "tcp-request connection sc-inc-gpt0" for a complete + description. + +tcp-request session set-dst <expr> [ { if | unless } <condition> ] +tcp-request session set-dst-port <expr> [ { if | unless } <condition> ] + + These actions are used to set the destination IP/Port address to the value of + specified expression. Please refer to "http-request set-dst" and + "http-request set-dst-port" for a complete description. + +tcp-request session set-mark <mark> [ { if | unless } <condition> ] + + This action is used to set the Netfilter/IPFW MARK in all packets sent to the + client to the value passed in <mark> on platforms which support it. Please + refer to "http-request set-mark" for a complete description. + +tcp-request session set-src <expr> [ { if | unless } <condition> ] +tcp-request session set-src-port <expr> [ { if | unless } <condition> ] + + These actions are used to set the source IP/Port address to the value of + specified expression. Please refer to "http-request set-src" and + "http-request set-src-port" for a complete description. + +tcp-request session set-tos <tos> [ { if | unless } <condition> ] + + This is used to set the TOS or DSCP field value of packets sent to the client + to the value passed in <tos> on platforms which support this. Please refer to + "http-request set-tos" for a complete description. + +tcp-request session set-var(<var-name>[,<cond>...]) <expr> [ { if | unless } <condition> ] +tcp-request session set-var-fmt(<var-name>[,<cond>...]) <fmt> [ { if | unless } <condition> ] + + This is used to set the contents of a variable. The variable is declared + inline. Please refer to "http-request set-var" and "http-request set-var-fmt" + for a complete description. + +tcp-request session silent-drop [ { if | unless } <condition> ] + + This stops the evaluation of the rules and makes the client-facing connection + suddenly disappear using a system-dependent way that tries to prevent the + client from being notified. Please refer to "http-request silent-drop" for a + complete description. + +tcp-request session track-sc0 <key> [table <table>] [ { if | unless } <condition> ] +tcp-request session track-sc1 <key> [table <table>] [ { if | unless } <condition> ] +tcp-request session track-sc2 <key> [table <table>] [ { if | unless } <condition> ] + + This enables tracking of sticky counters from current connection. Please + refer to "http-request track-sc0", "http-request track-sc1" and "http-request + track-sc2" for a complete description. + +tcp-request session unset-var(<var-name>) [ { if | unless } <condition> ] + + This is used to unset a variable. Please refer to "http-request set-var" for + details about variables. + + +tcp-response content <action> [{if | unless} <condition>] + Perform an action on a session response depending on a layer 4-7 condition + May be used in sections : defaults | frontend | listen | backend + yes(!) | no | yes | yes + Arguments : + <action> defines the action to perform if the condition applies. See + below. + + <condition> is a standard layer 4-7 ACL-based condition (see section 7). + + Response contents can be analyzed at an early stage of response processing + called "TCP content inspection". During this stage, ACL-based rules are + evaluated every time the response contents are updated, until either an + "accept", "close" or a "reject" rule matches, or a TCP response inspection + delay is set and expires with no matching rule. + + Most often, these decisions will consider a protocol recognition or validity. + + Content-based rules are evaluated in their exact declaration order. If no + rule matches or if there is no rule, the default action is to accept the + contents. There is no specific limit to the number of rules which may be + inserted. + + The first keyword is the rule's action. Several types of actions are + supported: + - accept + - close + - reject + - sc-inc-gpc(<idx>,<sc-id>) + - sc-inc-gpc0(<sc-id>) + - sc-inc-gpc1(<sc-id>) + - sc-set-gpt(<idx>,<sc-id>) { <int> | <expr> } + - sc-set-gpt0(<sc-id>) { <int> | <expr> } + - send-spoe-group <engine-name> <group-name> + - set-log-level <level> + - set-mark <mark> + - set-nice <nice> + - set-tos <tos> + - set-var(<var-name>[,<cond>...]) <expr> + - set-var-fmt(<var-name>[,<cond>...]) <fmt> + - silent-drop + - unset-var(<var-name>) + + The supported actions are described below. + + This directive is only available from named defaults sections, not anonymous + ones. Rules defined in the defaults section are evaluated before ones in the + associated proxy section. To avoid ambiguities, in this case the same + defaults section cannot be used by proxies with the frontend capability and + by proxies with the backend capability. It means a listen section cannot use + a defaults section defining such rules. + + Note that the "if/unless" condition is optional. If no condition is set on + the action, it is simply performed unconditionally. That can be useful for + for changing the default action to a reject. + + Several types of actions are supported : + + It is perfectly possible to match layer 7 contents with "tcp-response + content" rules, but then it is important to ensure that a full response has + been buffered, otherwise no contents will match. In order to achieve this, + the best solution involves detecting the HTTP protocol during the inspection + period. + + See section 7 about ACL usage. + + See also : "tcp-request content", "tcp-response inspect-delay" + +tcp-response content accept [ { if | unless } <condition> ] + + This is used to accept the response. No further "tcp-response content" rules + are evaluated. + +tcp-response content close [ { if | unless } <condition> ] + + This is used to immediately closes the connection with the server. No further + "tcp-response content" rules are evaluated. The main purpose of this action + is to force a connection to be finished between a client and a server after + an exchange when the application protocol expects some long time outs to + elapse first. The goal is to eliminate idle connections which take + significant resources on servers with certain protocols. + +tcp-response content reject [ { if | unless } <condition> ] + + This is used to reject the response. No further "tcp-response content" rules + are evaluated. + +tcp-response content sc-inc-gpc(<idx>,<sc-id>) [ { if | unless } <condition> ] +tcp-response content sc-inc-gpc0(<sc-id>) [ { if | unless } <condition> ] +tcp-response content sc-inc-gpc1(<sc-id>) [ { if | unless } <condition> ] + + These actions increment the General Purppose Counters according to the sticky + counter designated by <sc-id>. Please refer to "http-request sc-inc-gpc", + "http-request sc-inc-gpc0" and "http-request sc-inc-gpc1" for a complete + description. + +tcp-response content sc-set-gpt(<idx>,<sc-id>) { <int> | <expr> } + [ { if | unless } <condition> ] +tcp-resposne content sc-set-gpt0(<sc-id>) { <int> | <expr> } + [ { if | unless } <condition> ] + + These actions set the 32-bit unsigned General Purpose Tags according to the + sticky counter designated by <sc-id>. Please refer to "http-request + sc-inc-gpt" and "http-request sc-inc-gpt0" for a complete description. + +tcp-response content send-spoe-group <engine-name> <group-name> + [ { if | unless } <condition> ] + + Thaction is is used to trigger sending of a group of SPOE messages. Please + refer to "http-request send-spoe-group" for a complete description. + +tcp-response content set-log-level <level> [ { if | unless } <condition> ] + + This action is used to set the log level of the current session. Please refer + to "http-request set-log-level". for a complete description. + +tcp-response content set-mark <mark> [ { if | unless } <condition> ] + + This action is used to set the Netfilter/IPFW MARK in all packets sent to the + client to the value passed in <mark> on platforms which support it. Please + refer to "http-request set-mark" for a complete description. + +tcp-response content set-nice <nice> [ { if | unless } <condition> ] + + This sets the "nice" factor of the current request being processed. Please + refer to "http-request set-nice" for a complete description. + +tcp-response content set-tos <tos> [ { if | unless } <condition> ] + + This is used to set the TOS or DSCP field value of packets sent to the client + to the value passed in <tos> on platforms which support this. Please refer to + "http-request set-tos" for a complete description. + +tcp-response content set-var(<var-name>[,<cond>...]) <expr> [ { if | unless } <condition> ] +tcp-response content set-var-fmt(<var-name>[,<cond>...]) <fmt> [ { if | unless } <condition> ] + + This is used to set the contents of a variable. The variable is declared + inline. Please refer to "http-request set-var" and "http-request set-var-fmt" + for a complete description. + +tcp-response content silent-drop [ { if | unless } <condition> ] + + This stops the evaluation of the rules and makes the client-facing connection + suddenly disappear using a system-dependent way that tries to prevent the + client from being notified. Please refer to "http-request silent-drop" for a + complete description. + +tcp-response content unset-var(<var-name>) [ { if | unless } <condition> ] + + This is used to unset a variable. Please refer to "http-request set-var" for + details about variables. + + +tcp-response inspect-delay <timeout> + Set the maximum allowed time to wait for a response during content inspection + May be used in sections : defaults | frontend | listen | backend + yes(!) | no | yes | yes + Arguments : + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + This directive is only available from named defaults sections, not anonymous + ones. Proxies inherit this value from their defaults section. + + See also : "tcp-response content", "tcp-request inspect-delay". + + +timeout check <timeout> + Set additional check timeout, but only after a connection has been already + established. + + May be used in sections: defaults | frontend | listen | backend + yes | no | yes | yes + Arguments: + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + If set, HAProxy uses min("timeout connect", "inter") as a connect timeout + for check and "timeout check" as an additional read timeout. The "min" is + used so that people running with *very* long "timeout connect" (e.g. those + who needed this due to the queue or tarpit) do not slow down their checks. + (Please also note that there is no valid reason to have such long connect + timeouts, because "timeout queue" and "timeout tarpit" can always be used to + avoid that). + + If "timeout check" is not set HAProxy uses "inter" for complete check + timeout (connect + read) exactly like all <1.3.15 version. + + In most cases check request is much simpler and faster to handle than normal + requests and people may want to kick out laggy servers so this timeout should + be smaller than "timeout server". + + This parameter is specific to backends, but can be specified once for all in + "defaults" sections. This is in fact one of the easiest solutions not to + forget about it. + + This directive is only available from named defaults sections, not anonymous + ones. Proxies inherit this value from their defaults section. + + See also: "timeout connect", "timeout queue", "timeout server", + "timeout tarpit". + + +timeout client <timeout> + Set the maximum inactivity time on the client side. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + The inactivity timeout applies when the client is expected to acknowledge or + send data. In HTTP mode, this timeout is particularly important to consider + during the first phase, when the client sends the request, and during the + response while it is reading data sent by the server. That said, for the + first phase, it is preferable to set the "timeout http-request" to better + protect HAProxy from Slowloris like attacks. The value is specified in + milliseconds by default, but can be in any other unit if the number is + suffixed by the unit, as specified at the top of this document. In TCP mode + (and to a lesser extent, in HTTP mode), it is highly recommended that the + client timeout remains equal to the server timeout in order to avoid complex + situations to debug. It is a good practice to cover one or several TCP packet + losses by specifying timeouts that are slightly above multiples of 3 seconds + (e.g. 4 or 5 seconds). If some long-lived sessions are mixed with short-lived + sessions (e.g. WebSocket and HTTP), it's worth considering "timeout tunnel", + which overrides "timeout client" and "timeout server" for tunnels, as well as + "timeout client-fin" for half-closed connections. + + This parameter is specific to frontends, but can be specified once for all in + "defaults" sections. This is in fact one of the easiest solutions not to + forget about it. An unspecified timeout results in an infinite timeout, which + is not recommended. Such a usage is accepted and works but reports a warning + during startup because it may result in accumulation of expired sessions in + the system if the system's timeouts are not configured either. + + See also : "timeout server", "timeout tunnel", "timeout http-request". + + +timeout client-fin <timeout> + Set the inactivity timeout on the client side for half-closed connections. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + The inactivity timeout applies when the client is expected to acknowledge or + send data while one direction is already shut down. This timeout is different + from "timeout client" in that it only applies to connections which are closed + in one direction. This is particularly useful to avoid keeping connections in + FIN_WAIT state for too long when clients do not disconnect cleanly. This + problem is particularly common long connections such as RDP or WebSocket. + Note that this timeout can override "timeout tunnel" when a connection shuts + down in one direction. It is applied to idle HTTP/2 connections once a GOAWAY + frame was sent, often indicating an expectation that the connection quickly + ends. + + This parameter is specific to frontends, but can be specified once for all in + "defaults" sections. By default it is not set, so half-closed connections + will use the other timeouts (timeout.client or timeout.tunnel). + + See also : "timeout client", "timeout server-fin", and "timeout tunnel". + + +timeout connect <timeout> + Set the maximum time to wait for a connection attempt to a server to succeed. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + If the server is located on the same LAN as HAProxy, the connection should be + immediate (less than a few milliseconds). Anyway, it is a good practice to + cover one or several TCP packet losses by specifying timeouts that are + slightly above multiples of 3 seconds (e.g. 4 or 5 seconds). By default, the + connect timeout also presets both queue and tarpit timeouts to the same value + if these have not been specified. + + This parameter is specific to backends, but can be specified once for all in + "defaults" sections. This is in fact one of the easiest solutions not to + forget about it. An unspecified timeout results in an infinite timeout, which + is not recommended. Such a usage is accepted and works but reports a warning + during startup because it may result in accumulation of failed sessions in + the system if the system's timeouts are not configured either. + + See also: "timeout check", "timeout queue", "timeout server", "timeout tarpit". + + +timeout http-keep-alive <timeout> + Set the maximum allowed time to wait for a new HTTP request to appear + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + By default, the time to wait for a new request in case of keep-alive is set + by "timeout http-request". However this is not always convenient because some + people want very short keep-alive timeouts in order to release connections + faster, and others prefer to have larger ones but still have short timeouts + once the request has started to present itself. + + The "http-keep-alive" timeout covers these needs. It will define how long to + wait for a new HTTP request to start coming after a response was sent. Once + the first byte of request has been seen, the "http-request" timeout is used + to wait for the complete request to come. Note that empty lines prior to a + new request do not refresh the timeout and are not counted as a new request. + + There is also another difference between the two timeouts : when a connection + expires during timeout http-keep-alive, no error is returned, the connection + just closes. If the connection expires in "http-request" while waiting for a + connection to complete, a HTTP 408 error is returned. + + In general it is optimal to set this value to a few tens to hundreds of + milliseconds, to allow users to fetch all objects of a page at once but + without waiting for further clicks. Also, if set to a very small value (e.g. + 1 millisecond) it will probably only accept pipelined requests but not the + non-pipelined ones. It may be a nice trade-off for very large sites running + with tens to hundreds of thousands of clients. + + If this parameter is not set, the "http-request" timeout applies, and if both + are not set, "timeout client" still applies at the lower level. It should be + set in the frontend to take effect, unless the frontend is in TCP mode, in + which case the HTTP backend's timeout will be used. + + See also : "timeout http-request", "timeout client". + + +timeout http-request <timeout> + Set the maximum allowed time to wait for a complete HTTP request + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + In order to offer DoS protection, it may be required to lower the maximum + accepted time to receive a complete HTTP request without affecting the client + timeout. This helps protecting against established connections on which + nothing is sent. The client timeout cannot offer a good protection against + this abuse because it is an inactivity timeout, which means that if the + attacker sends one character every now and then, the timeout will not + trigger. With the HTTP request timeout, no matter what speed the client + types, the request will be aborted if it does not complete in time. When the + timeout expires, an HTTP 408 response is sent to the client to inform it + about the problem, and the connection is closed. The logs will report + termination codes "cR". Some recent browsers are having problems with this + standard, well-documented behavior, so it might be needed to hide the 408 + code using "option http-ignore-probes" or "errorfile 408 /dev/null". See + more details in the explanations of the "cR" termination code in section 8.5. + + By default, this timeout only applies to the header part of the request, + and not to any data. As soon as the empty line is received, this timeout is + not used anymore. When combined with "option http-buffer-request", this + timeout also applies to the body of the request.. + It is used again on keep-alive connections to wait for a second + request if "timeout http-keep-alive" is not set. + + Generally it is enough to set it to a few seconds, as most clients send the + full request immediately upon connection. Add 3 or more seconds to cover TCP + retransmits but that's all. Setting it to very low values (e.g. 50 ms) will + generally work on local networks as long as there are no packet losses. This + will prevent people from sending bare HTTP requests using telnet. + + If this parameter is not set, the client timeout still applies between each + chunk of the incoming request. It should be set in the frontend to take + effect, unless the frontend is in TCP mode, in which case the HTTP backend's + timeout will be used. + + See also : "errorfile", "http-ignore-probes", "timeout http-keep-alive", and + "timeout client", "option http-buffer-request". + + +timeout queue <timeout> + Set the maximum time to wait in the queue for a connection slot to be free + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + When a server's maxconn is reached, connections are left pending in a queue + which may be server-specific or global to the backend. In order not to wait + indefinitely, a timeout is applied to requests pending in the queue. If the + timeout is reached, it is considered that the request will almost never be + served, so it is dropped and a 503 error is returned to the client. + + The "timeout queue" statement allows to fix the maximum time for a request to + be left pending in a queue. If unspecified, the same value as the backend's + connection timeout ("timeout connect") is used, for backwards compatibility + with older versions with no "timeout queue" parameter. + + See also : "timeout connect". + + +timeout server <timeout> + Set the maximum inactivity time on the server side. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + The inactivity timeout applies when the server is expected to acknowledge or + send data. In HTTP mode, this timeout is particularly important to consider + during the first phase of the server's response, when it has to send the + headers, as it directly represents the server's processing time for the + request. To find out what value to put there, it's often good to start with + what would be considered as unacceptable response times, then check the logs + to observe the response time distribution, and adjust the value accordingly. + + The value is specified in milliseconds by default, but can be in any other + unit if the number is suffixed by the unit, as specified at the top of this + document. In TCP mode (and to a lesser extent, in HTTP mode), it is highly + recommended that the client timeout remains equal to the server timeout in + order to avoid complex situations to debug. Whatever the expected server + response times, it is a good practice to cover at least one or several TCP + packet losses by specifying timeouts that are slightly above multiples of 3 + seconds (e.g. 4 or 5 seconds minimum). If some long-lived sessions are mixed + with short-lived sessions (e.g. WebSocket and HTTP), it's worth considering + "timeout tunnel", which overrides "timeout client" and "timeout server" for + tunnels. + + This parameter is specific to backends, but can be specified once for all in + "defaults" sections. This is in fact one of the easiest solutions not to + forget about it. An unspecified timeout results in an infinite timeout, which + is not recommended. Such a usage is accepted and works but reports a warning + during startup because it may result in accumulation of expired sessions in + the system if the system's timeouts are not configured either. + + See also : "timeout client" and "timeout tunnel". + + +timeout server-fin <timeout> + Set the inactivity timeout on the server side for half-closed connections. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + The inactivity timeout applies when the server is expected to acknowledge or + send data while one direction is already shut down. This timeout is different + from "timeout server" in that it only applies to connections which are closed + in one direction. This is particularly useful to avoid keeping connections in + FIN_WAIT state for too long when a remote server does not disconnect cleanly. + This problem is particularly common long connections such as RDP or WebSocket. + Note that this timeout can override "timeout tunnel" when a connection shuts + down in one direction. This setting was provided for completeness, but in most + situations, it should not be needed. + + This parameter is specific to backends, but can be specified once for all in + "defaults" sections. By default it is not set, so half-closed connections + will use the other timeouts (timeout.server or timeout.tunnel). + + See also : "timeout client-fin", "timeout server", and "timeout tunnel". + + +timeout tarpit <timeout> + Set the duration for which tarpitted connections will be maintained + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | yes + Arguments : + <timeout> is the tarpit duration specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + When a connection is tarpitted using "http-request tarpit", it is maintained + open with no activity for a certain amount of time, then closed. "timeout + tarpit" defines how long it will be maintained open. + + The value is specified in milliseconds by default, but can be in any other + unit if the number is suffixed by the unit, as specified at the top of this + document. If unspecified, the same value as the backend's connection timeout + ("timeout connect") is used, for backwards compatibility with older versions + with no "timeout tarpit" parameter. + + See also : "timeout connect". + + +timeout tunnel <timeout> + Set the maximum inactivity time on the client and server side for tunnels. + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : + <timeout> is the timeout value specified in milliseconds by default, but + can be in any other unit if the number is suffixed by the unit, + as explained at the top of this document. + + The tunnel timeout applies when a bidirectional connection is established + between a client and a server, and the connection remains inactive in both + directions. This timeout supersedes both the client and server timeouts once + the connection becomes a tunnel. In TCP, this timeout is used as soon as no + analyzer remains attached to either connection (e.g. tcp content rules are + accepted). In HTTP, this timeout is used when a connection is upgraded (e.g. + when switching to the WebSocket protocol, or forwarding a CONNECT request + to a proxy), or after the first response when no keepalive/close option is + specified. + + Since this timeout is usually used in conjunction with long-lived connections, + it usually is a good idea to also set "timeout client-fin" to handle the + situation where a client suddenly disappears from the net and does not + acknowledge a close, or sends a shutdown and does not acknowledge pending + data anymore. This can happen in lossy networks where firewalls are present, + and is detected by the presence of large amounts of sessions in a FIN_WAIT + state. + + The value is specified in milliseconds by default, but can be in any other + unit if the number is suffixed by the unit, as specified at the top of this + document. Whatever the expected normal idle time, it is a good practice to + cover at least one or several TCP packet losses by specifying timeouts that + are slightly above multiples of 3 seconds (e.g. 4 or 5 seconds minimum). + + This parameter is specific to backends, but can be specified once for all in + "defaults" sections. This is in fact one of the easiest solutions not to + forget about it. + + Example : + defaults http + option http-server-close + timeout connect 5s + timeout client 30s + timeout client-fin 30s + timeout server 30s + timeout tunnel 1h # timeout to use with WebSocket and CONNECT + + See also : "timeout client", "timeout client-fin", "timeout server". + + +transparent (deprecated) + Enable client-side transparent proxying + May be used in sections : defaults | frontend | listen | backend + yes | no | yes | yes + Arguments : none + + This keyword was introduced in order to provide layer 7 persistence to layer + 3 load balancers. The idea is to use the OS's ability to redirect an incoming + connection for a remote address to a local process (here HAProxy), and let + this process know what address was initially requested. When this option is + used, sessions without cookies will be forwarded to the original destination + IP address of the incoming request (which should match that of another + equipment), while requests with cookies will still be forwarded to the + appropriate server. + + The "transparent" keyword is deprecated, use "option transparent" instead. + + Note that contrary to a common belief, this option does NOT make HAProxy + present the client's IP to the server when establishing the connection. + + See also: "option transparent" + +unique-id-format <string> + Generate a unique ID for each request. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : + <string> is a log-format string. + + This keyword creates a ID for each request using the custom log format. A + unique ID is useful to trace a request passing through many components of + a complex infrastructure. The newly created ID may also be logged using the + %ID tag the log-format string. + + The format should be composed from elements that are guaranteed to be + unique when combined together. For instance, if multiple HAProxy instances + are involved, it might be important to include the node name. It is often + needed to log the incoming connection's source and destination addresses + and ports. Note that since multiple requests may be performed over the same + connection, including a request counter may help differentiate them. + Similarly, a timestamp may protect against a rollover of the counter. + Logging the process ID will avoid collisions after a service restart. + + It is recommended to use hexadecimal notation for many fields since it + makes them more compact and saves space in logs. + + Example: + + unique-id-format %{+X}o\ %ci:%cp_%fi:%fp_%Ts_%rt:%pid + + will generate: + + 7F000001:8296_7F00001E:1F90_4F7B0A69_0003:790A + + See also: "unique-id-header" + +unique-id-header <name> + Add a unique ID header in the HTTP request. + May be used in sections : defaults | frontend | listen | backend + yes | yes | yes | no + Arguments : + <name> is the name of the header. + + Add a unique-id header in the HTTP request sent to the server, using the + unique-id-format. It can't work if the unique-id-format doesn't exist. + + Example: + + unique-id-format %{+X}o\ %ci:%cp_%fi:%fp_%Ts_%rt:%pid + unique-id-header X-Unique-ID + + will generate: + + X-Unique-ID: 7F000001:8296_7F00001E:1F90_4F7B0A69_0003:790A + + See also: "unique-id-format" + +use_backend <backend> [{if | unless} <condition>] + Switch to a specific backend if/unless an ACL-based condition is matched. + May be used in sections : defaults | frontend | listen | backend + no | yes | yes | no + Arguments : + <backend> is the name of a valid backend or "listen" section, or a + "log-format" string resolving to a backend name. + + <condition> is a condition composed of ACLs, as described in section 7. If + it is omitted, the rule is unconditionally applied. + + When doing content-switching, connections arrive on a frontend and are then + dispatched to various backends depending on a number of conditions. The + relation between the conditions and the backends is described with the + "use_backend" keyword. While it is normally used with HTTP processing, it can + also be used in pure TCP, either without content using stateless ACLs (e.g. + source address validation) or combined with a "tcp-request" rule to wait for + some payload. + + There may be as many "use_backend" rules as desired. All of these rules are + evaluated in their declaration order, and the first one which matches will + assign the backend. + + In the first form, the backend will be used if the condition is met. In the + second form, the backend will be used if the condition is not met. If no + condition is valid, the backend defined with "default_backend" will be used. + If no default backend is defined, either the servers in the same section are + used (in case of a "listen" section) or, in case of a frontend, no server is + used and a 503 service unavailable response is returned. + + Note that it is possible to switch from a TCP frontend to an HTTP backend. In + this case, either the frontend has already checked that the protocol is HTTP, + and backend processing will immediately follow, or the backend will wait for + a complete HTTP request to get in. This feature is useful when a frontend + must decode several protocols on a unique port, one of them being HTTP. + + When <backend> is a simple name, it is resolved at configuration time, and an + error is reported if the specified backend does not exist. If <backend> is + a log-format string instead, no check may be done at configuration time, so + the backend name is resolved dynamically at run time. If the resulting + backend name does not correspond to any valid backend, no other rule is + evaluated, and the default_backend directive is applied instead. Note that + when using dynamic backend names, it is highly recommended to use a prefix + that no other backend uses in order to ensure that an unauthorized backend + cannot be forced from the request. + + It is worth mentioning that "use_backend" rules with an explicit name are + used to detect the association between frontends and backends to compute the + backend's "fullconn" setting. This cannot be done for dynamic names. + + See also: "default_backend", "tcp-request", "fullconn", "log-format", and + section 7 about ACLs. + +use-fcgi-app <name> + Defines the FastCGI application to use for the backend. + May be used in sections : defaults | frontend | listen | backend + no | no | yes | yes + Arguments : + <name> is the name of the FastCGI application to use. + + See section 10.1 about FastCGI application setup for details. + +use-server <server> if <condition> +use-server <server> unless <condition> + Only use a specific server if/unless an ACL-based condition is matched. + May be used in sections : defaults | frontend | listen | backend + no | no | yes | yes + Arguments : + <server> is the name of a valid server in the same backend section + or a "log-format" string resolving to a server name. + + <condition> is a condition composed of ACLs, as described in section 7. + + By default, connections which arrive to a backend are load-balanced across + the available servers according to the configured algorithm, unless a + persistence mechanism such as a cookie is used and found in the request. + + Sometimes it is desirable to forward a particular request to a specific + server without having to declare a dedicated backend for this server. This + can be achieved using the "use-server" rules. These rules are evaluated after + the "redirect" rules and before evaluating cookies, and they have precedence + on them. There may be as many "use-server" rules as desired. All of these + rules are evaluated in their declaration order, and the first one which + matches will assign the server. + + If a rule designates a server which is down, and "option persist" is not used + and no force-persist rule was validated, it is ignored and evaluation goes on + with the next rules until one matches. + + In the first form, the server will be used if the condition is met. In the + second form, the server will be used if the condition is not met. If no + condition is valid, the processing continues and the server will be assigned + according to other persistence mechanisms. + + Note that even if a rule is matched, cookie processing is still performed but + does not assign the server. This allows prefixed cookies to have their prefix + stripped. + + The "use-server" statement works both in HTTP and TCP mode. This makes it + suitable for use with content-based inspection. For instance, a server could + be selected in a farm according to the TLS SNI field when using protocols with + implicit TLS (also see "req.ssl_sni"). And if these servers have their weight + set to zero, they will not be used for other traffic. + + Example : + # intercept incoming TLS requests based on the SNI field + use-server www if { req.ssl_sni -i www.example.com } + server www 192.168.0.1:443 weight 0 + use-server mail if { req.ssl_sni -i mail.example.com } + server mail 192.168.0.1:465 weight 0 + use-server imap if { req.ssl_sni -i imap.example.com } + server imap 192.168.0.1:993 weight 0 + # all the rest is forwarded to this server + server default 192.168.0.2:443 check + + When <server> is a simple name, it is checked against existing servers in the + configuration and an error is reported if the specified server does not exist. + If it is a log-format, no check is performed when parsing the configuration, + and if we can't resolve a valid server name at runtime but the use-server rule + was conditioned by an ACL returning true, no other use-server rule is applied + and we fall back to load balancing. + + See also: "use_backend", section 5 about server and section 7 about ACLs. + + +5. Bind and server options +-------------------------- + +The "bind", "server" and "default-server" keywords support a number of settings +depending on some build options and on the system HAProxy was built on. These +settings generally each consist in one word sometimes followed by a value, +written on the same line as the "bind" or "server" line. All these options are +described in this section. + + +5.1. Bind options +----------------- + +The "bind" keyword supports a certain number of settings which are all passed +as arguments on the same line. The order in which those arguments appear makes +no importance, provided that they appear after the bind address. All of these +parameters are optional. Some of them consist in a single words (booleans), +while other ones expect a value after them. In this case, the value must be +provided immediately after the setting name. + +The currently supported settings are the following ones. + +accept-netscaler-cip <magic number> + Enforces the use of the NetScaler Client IP insertion protocol over any + connection accepted by any of the TCP sockets declared on the same line. The + NetScaler Client IP insertion protocol dictates the layer 3/4 addresses of + the incoming connection to be used everywhere an address is used, with the + only exception of "tcp-request connection" rules which will only see the + real connection address. Logs will reflect the addresses indicated in the + protocol, unless it is violated, in which case the real address will still + be used. This keyword combined with support from external components can be + used as an efficient and reliable alternative to the X-Forwarded-For + mechanism which is not always reliable and not even always usable. See also + "tcp-request connection expect-netscaler-cip" for a finer-grained setting of + which client is allowed to use the protocol. + +accept-proxy + Enforces the use of the PROXY protocol over any connection accepted by any of + the sockets declared on the same line. Versions 1 and 2 of the PROXY protocol + are supported and correctly detected. The PROXY protocol dictates the layer + 3/4 addresses of the incoming connection to be used everywhere an address is + used, with the only exception of "tcp-request connection" rules which will + only see the real connection address. Logs will reflect the addresses + indicated in the protocol, unless it is violated, in which case the real + address will still be used. This keyword combined with support from external + components can be used as an efficient and reliable alternative to the + X-Forwarded-For mechanism which is not always reliable and not even always + usable. See also "tcp-request connection expect-proxy" for a finer-grained + setting of which client is allowed to use the protocol. + +allow-0rtt + Allow receiving early data when using TLSv1.3. This is disabled by default, + due to security considerations. Because it is vulnerable to replay attacks, + you should only allow if for requests that are safe to replay, i.e. requests + that are idempotent. You can use the "wait-for-handshake" action for any + request that wouldn't be safe with early data. + +alpn <protocols> + This enables the TLS ALPN extension and advertises the specified protocol + list as supported on top of ALPN. The protocol list consists in a comma- + delimited list of protocol names, for instance: "http/1.1,http/1.0" (without + quotes). This requires that the SSL library is built with support for TLS + extensions enabled (check with haproxy -vv). The ALPN extension replaces the + initial NPN extension. ALPN is required to enable HTTP/2 on an HTTP frontend. + Versions of OpenSSL prior to 1.0.2 didn't support ALPN and only supposed the + now obsolete NPN extension. At the time of writing this, most browsers still + support both ALPN and NPN for HTTP/2 so a fallback to NPN may still work for + a while. But ALPN must be used whenever possible. If both HTTP/2 and HTTP/1.1 + are expected to be supported, both versions can be advertised, in order of + preference, like below : + + bind :443 ssl crt pub.pem alpn h2,http/1.1 + + QUIC supports only h3 and hq-interop as ALPN. h3 is for HTTP/3 and hq-interop + is used for http/0.9 and QUIC interop runner (see https://interop.seemann.io). + +backlog <backlog> + Sets the socket's backlog to this value. If unspecified or 0, the frontend's + backlog is used instead, which generally defaults to the maxconn value. + +curves <curves> + This setting is only available when support for OpenSSL was built in. It sets + the string describing the list of elliptic curves algorithms ("curve suite") + that are negotiated during the SSL/TLS handshake with ECDHE. The format of the + string is a colon-delimited list of curve name. + Example: "X25519:P-256" (without quote) + When "curves" is set, "ecdhe" parameter is ignored. + +ecdhe <named curve> + This setting is only available when support for OpenSSL was built in. It sets + the named curve (RFC 4492) used to generate ECDH ephemeral keys. By default, + used named curve is prime256v1. + +ca-file <cafile> + This setting is only available when support for OpenSSL was built in. It + designates a PEM file from which to load CA certificates used to verify + client's certificate. It is possible to load a directory containing multiple + CAs, in this case HAProxy will try to load every ".pem", ".crt", ".cer", and + .crl" available in the directory, files starting with a dot are ignored. + + Warning: The "@system-ca" parameter could be used in place of the cafile + in order to use the trusted CAs of your system, like its done with the server + directive. But you mustn't use it unless you know what you are doing. + Configuring it this way basically mean that the bind will accept any client + certificate generated from one of the CA present on your system, which is + extremely unsecure. + +ca-ignore-err [all|<errorID>,...] + This setting is only available when support for OpenSSL was built in. + Sets a comma separated list of errorIDs to ignore during verify at depth > 0. + If set to 'all', all errors are ignored. SSL handshake is not aborted if an + error is ignored. + +ca-sign-file <cafile> + This setting is only available when support for OpenSSL was built in. It + designates a PEM file containing both the CA certificate and the CA private + key used to create and sign server's certificates. This is a mandatory + setting when the dynamic generation of certificates is enabled. See + 'generate-certificates' for details. + +ca-sign-pass <passphrase> + This setting is only available when support for OpenSSL was built in. It is + the CA private key passphrase. This setting is optional and used only when + the dynamic generation of certificates is enabled. See + 'generate-certificates' for details. + +ca-verify-file <cafile> + This setting designates a PEM file from which to load CA certificates used to + verify client's certificate. It designates CA certificates which must not be + included in CA names sent in server hello message. Typically, "ca-file" must + be defined with intermediate certificates, and "ca-verify-file" with + certificates to ending the chain, like root CA. + +ciphers <ciphers> + This setting is only available when support for OpenSSL was built in. It sets + the string describing the list of cipher algorithms ("cipher suite") that are + negotiated during the SSL/TLS handshake up to TLSv1.2. The format of the + string is defined in "man 1 ciphers" from OpenSSL man pages. For background + information and recommendations see e.g. + (https://wiki.mozilla.org/Security/Server_Side_TLS) and + (https://mozilla.github.io/server-side-tls/ssl-config-generator/). For TLSv1.3 + cipher configuration, please check the "ciphersuites" keyword. + +ciphersuites <ciphersuites> + This setting is only available when support for OpenSSL was built in and + OpenSSL 1.1.1 or later was used to build HAProxy. It sets the string describing + the list of cipher algorithms ("cipher suite") that are negotiated during the + TLSv1.3 handshake. The format of the string is defined in "man 1 ciphers" from + OpenSSL man pages under the "ciphersuites" section. For cipher configuration + for TLSv1.2 and earlier, please check the "ciphers" keyword. + +crl-file <crlfile> + This setting is only available when support for OpenSSL was built in. It + designates a PEM file from which to load certificate revocation list used + to verify client's certificate. You need to provide a certificate revocation + list for every certificate of your certificate authority chain. + +crt <cert> + This setting is only available when support for OpenSSL was built in. It + designates a PEM file containing both the required certificates and any + associated private keys. This file can be built by concatenating multiple + PEM files into one (e.g. cat cert.pem key.pem > combined.pem). If your CA + requires an intermediate certificate, this can also be concatenated into this + file. Intermediate certificate can also be shared in a directory via + "issuers-chain-path" directive. + + If the file does not contain a private key, HAProxy will try to load + the key at the same path suffixed by a ".key". + + If the OpenSSL used supports Diffie-Hellman, parameters present in this file + are loaded. + + If a directory name is used instead of a PEM file, then all files found in + that directory will be loaded in alphabetic order unless their name ends + with '.key', '.issuer', '.ocsp' or '.sctl' (reserved extensions). Files + starting with a dot are also ignored. This directive may be specified multiple + times in order to load certificates from multiple files or directories. The + certificates will be presented to clients who provide a valid TLS Server Name + Indication field matching one of their CN or alt subjects. Wildcards are + supported, where a wildcard character '*' is used instead of the first + hostname component (e.g. *.example.org matches www.example.org but not + www.sub.example.org). + + If no SNI is provided by the client or if the SSL library does not support + TLS extensions, or if the client provides an SNI hostname which does not + match any certificate, then the first loaded certificate will be presented. + This means that when loading certificates from a directory, it is highly + recommended to load the default one first as a file or to ensure that it will + always be the first one in the directory. + + Note that the same cert may be loaded multiple times without side effects. + + Some CAs (such as GoDaddy) offer a drop down list of server types that do not + include HAProxy when obtaining a certificate. If this happens be sure to + choose a web server that the CA believes requires an intermediate CA (for + GoDaddy, selection Apache Tomcat will get the correct bundle, but many + others, e.g. nginx, result in a wrong bundle that will not work for some + clients). + + For each PEM file, HAProxy checks for the presence of file at the same path + suffixed by ".ocsp". If such file is found, support for the TLS Certificate + Status Request extension (also known as "OCSP stapling") is automatically + enabled. The content of this file is optional. If not empty, it must contain + a valid OCSP Response in DER format. In order to be valid an OCSP Response + must comply with the following rules: it has to indicate a good status, + it has to be a single response for the certificate of the PEM file, and it + has to be valid at the moment of addition. If these rules are not respected + the OCSP Response is ignored and a warning is emitted. In order to identify + which certificate an OCSP Response applies to, the issuer's certificate is + necessary. If the issuer's certificate is not found in the PEM file, it will + be loaded from a file at the same path as the PEM file suffixed by ".issuer" + if it exists otherwise it will fail with an error. + + For each PEM file, HAProxy also checks for the presence of file at the same + path suffixed by ".sctl". If such file is found, support for Certificate + Transparency (RFC6962) TLS extension is enabled. The file must contain a + valid Signed Certificate Timestamp List, as described in RFC. File is parsed + to check basic syntax, but no signatures are verified. + + There are cases where it is desirable to support multiple key types, e.g. RSA + and ECDSA in the cipher suites offered to the clients. This allows clients + that support EC certificates to be able to use EC ciphers, while + simultaneously supporting older, RSA only clients. + + To achieve this, OpenSSL 1.1.1 is required, you can configure this behavior + by providing one crt entry per certificate type, or by configuring a "cert + bundle" like it was required before HAProxy 1.8. See "ssl-load-extra-files". + +crt-ignore-err <errors> + This setting is only available when support for OpenSSL was built in. Sets a + comma separated list of errorIDs to ignore during verify at depth == 0. If + set to 'all', all errors are ignored. SSL handshake is not aborted if an error + is ignored. + +crt-list <file> + This setting is only available when support for OpenSSL was built in. It + designates a list of PEM file with an optional ssl configuration and a SNI + filter per certificate, with the following format for each line : + + <crtfile> [\[<sslbindconf> ...\]] [[!]<snifilter> ...] + + sslbindconf supports "allow-0rtt", "alpn", "ca-file", "ca-verify-file", + "ciphers", "ciphersuites", "crl-file", "curves", "ecdhe", "no-ca-names", + "npn", "verify" configuration. With BoringSSL and Openssl >= 1.1.1 + "ssl-min-ver" and "ssl-max-ver" are also supported. It overrides the + configuration set in bind line for the certificate. + + Wildcards are supported in the SNI filter. Negative filter are also supported, + useful in combination with a wildcard filter to exclude a particular SNI, or + after the first certificate to exclude a pattern from its CN or Subject Alt + Name (SAN). The certificates will be presented to clients who provide a valid + TLS Server Name Indication field matching one of the SNI filters. If no SNI + filter is specified, the CN and SAN are used. This directive may be specified + multiple times. See the "crt" option for more information. The default + certificate is still needed to meet OpenSSL expectations. If it is not used, + the 'strict-sni' option may be used. + + Multi-cert bundling (see "ssl-load-extra-files") is supported with crt-list, + as long as only the base name is given in the crt-list. SNI filter will do + the same work on all bundled certificates. + + Empty lines as well as lines beginning with a hash ('#') will be ignored. + + The first declared certificate of a bind line is used as the default + certificate, either from crt or crt-list option, which HAProxy should use in + the TLS handshake if no other certificate matches. This certificate will also + be used if the provided SNI matches its CN or SAN, even if a matching SNI + filter is found on any crt-list. The SNI filter !* can be used after the first + declared certificate to not include its CN and SAN in the SNI tree, so it will + never match except if no other certificate matches. This way the first + declared certificate act as a fallback. + + crt-list file example: + cert1.pem !* + # comment + cert2.pem [alpn h2,http/1.1] + certW.pem *.domain.tld !secure.domain.tld + certS.pem [curves X25519:P-256 ciphers ECDHE-ECDSA-AES256-GCM-SHA384] secure.domain.tld + +defer-accept + Is an optional keyword which is supported only on certain Linux kernels. It + states that a connection will only be accepted once some data arrive on it, + or at worst after the first retransmit. This should be used only on protocols + for which the client talks first (e.g. HTTP). It can slightly improve + performance by ensuring that most of the request is already available when + the connection is accepted. On the other hand, it will not be able to detect + connections which don't talk. It is important to note that this option is + broken in all kernels up to 2.6.31, as the connection is never accepted until + the client talks. This can cause issues with front firewalls which would see + an established connection while the proxy will only see it in SYN_RECV. This + option is only supported on TCPv4/TCPv6 sockets and ignored by other ones. + +expose-fd listeners + This option is only usable with the stats socket. It gives your stats socket + the capability to pass listeners FD to another HAProxy process. + In master-worker mode, this is not required anymore, the listeners will be + passed using the internal socketpairs between the master and the workers. + See also "-x" in the management guide. + +force-sslv3 + This option enforces use of SSLv3 only on SSL connections instantiated from + this listener. SSLv3 is generally less expensive than the TLS counterparts + for high connection rates. This option is also available on global statement + "ssl-default-bind-options". See also "ssl-min-ver" and "ssl-max-ver". + +force-tlsv10 + This option enforces use of TLSv1.0 only on SSL connections instantiated from + this listener. This option is also available on global statement + "ssl-default-bind-options". See also "ssl-min-ver" and "ssl-max-ver". + +force-tlsv11 + This option enforces use of TLSv1.1 only on SSL connections instantiated from + this listener. This option is also available on global statement + "ssl-default-bind-options". See also "ssl-min-ver" and "ssl-max-ver". + +force-tlsv12 + This option enforces use of TLSv1.2 only on SSL connections instantiated from + this listener. This option is also available on global statement + "ssl-default-bind-options". See also "ssl-min-ver" and "ssl-max-ver". + +force-tlsv13 + This option enforces use of TLSv1.3 only on SSL connections instantiated from + this listener. This option is also available on global statement + "ssl-default-bind-options". See also "ssl-min-ver" and "ssl-max-ver". + +generate-certificates + This setting is only available when support for OpenSSL was built in. It + enables the dynamic SSL certificates generation. A CA certificate and its + private key are necessary (see 'ca-sign-file'). When HAProxy is configured as + a transparent forward proxy, SSL requests generate errors because of a common + name mismatch on the certificate presented to the client. With this option + enabled, HAProxy will try to forge a certificate using the SNI hostname + indicated by the client. This is done only if no certificate matches the SNI + hostname (see 'crt-list'). If an error occurs, the default certificate is + used, else the 'strict-sni' option is set. + It can also be used when HAProxy is configured as a reverse proxy to ease the + deployment of an architecture with many backends. + + Creating a SSL certificate is an expensive operation, so a LRU cache is used + to store forged certificates (see 'tune.ssl.ssl-ctx-cache-size'). It + increases the HAProxy's memory footprint to reduce latency when the same + certificate is used many times. + +gid <gid> + Sets the group of the UNIX sockets to the designated system gid. It can also + be set by default in the global section's "unix-bind" statement. Note that + some platforms simply ignore this. This setting is equivalent to the "group" + setting except that the group ID is used instead of its name. This setting is + ignored by non UNIX sockets. + +group <group> + Sets the group of the UNIX sockets to the designated system group. It can + also be set by default in the global section's "unix-bind" statement. Note + that some platforms simply ignore this. This setting is equivalent to the + "gid" setting except that the group name is used instead of its gid. This + setting is ignored by non UNIX sockets. + +id <id> + Fixes the socket ID. By default, socket IDs are automatically assigned, but + sometimes it is more convenient to fix them to ease monitoring. This value + must be strictly positive and unique within the listener/frontend. This + option can only be used when defining only a single socket. + +interface <interface> + Restricts the socket to a specific interface. When specified, only packets + received from that particular interface are processed by the socket. This is + currently only supported on Linux. The interface must be a primary system + interface, not an aliased interface. It is also possible to bind multiple + frontends to the same address if they are bound to different interfaces. Note + that binding to a network interface requires root privileges. This parameter + is only compatible with TCPv4/TCPv6 sockets. When specified, return traffic + uses the same interface as inbound traffic, and its associated routing table, + even if there are explicit routes through different interfaces configured. + This can prove useful to address asymmetric routing issues when the same + client IP addresses need to be able to reach frontends hosted on different + interfaces. + +level <level> + This setting is used with the stats sockets only to restrict the nature of + the commands that can be issued on the socket. It is ignored by other + sockets. <level> can be one of : + - "user" is the least privileged level; only non-sensitive stats can be + read, and no change is allowed. It would make sense on systems where it + is not easy to restrict access to the socket. + - "operator" is the default level and fits most common uses. All data can + be read, and only non-sensitive changes are permitted (e.g. clear max + counters). + - "admin" should be used with care, as everything is permitted (e.g. clear + all counters). + +severity-output <format> + This setting is used with the stats sockets only to configure severity + level output prepended to informational feedback messages. Severity + level of messages can range between 0 and 7, conforming to syslog + rfc5424. Valid and successful socket commands requesting data + (i.e. "show map", "get acl foo" etc.) will never have a severity level + prepended. It is ignored by other sockets. <format> can be one of : + - "none" (default) no severity level is prepended to feedback messages. + - "number" severity level is prepended as a number. + - "string" severity level is prepended as a string following the + rfc5424 convention. + +maxconn <maxconn> + Limits the sockets to this number of concurrent connections. Extraneous + connections will remain in the system's backlog until a connection is + released. If unspecified, the limit will be the same as the frontend's + maxconn. Note that in case of port ranges or multiple addresses, the same + value will be applied to each socket. This setting enables different + limitations on expensive sockets, for instance SSL entries which may easily + eat all memory. + +mode <mode> + Sets the octal mode used to define access permissions on the UNIX socket. It + can also be set by default in the global section's "unix-bind" statement. + Note that some platforms simply ignore this. This setting is ignored by non + UNIX sockets. + +mss <maxseg> + Sets the TCP Maximum Segment Size (MSS) value to be advertised on incoming + connections. This can be used to force a lower MSS for certain specific + ports, for instance for connections passing through a VPN. Note that this + relies on a kernel feature which is theoretically supported under Linux but + was buggy in all versions prior to 2.6.28. It may or may not work on other + operating systems. It may also not change the advertised value but change the + effective size of outgoing segments. The commonly advertised value for TCPv4 + over Ethernet networks is 1460 = 1500(MTU) - 40(IP+TCP). If this value is + positive, it will be used as the advertised MSS. If it is negative, it will + indicate by how much to reduce the incoming connection's advertised MSS for + outgoing segments. This parameter is only compatible with TCP v4/v6 sockets. + +name <name> + Sets an optional name for these sockets, which will be reported on the stats + page. + +namespace <name> + On Linux, it is possible to specify which network namespace a socket will + belong to. This directive makes it possible to explicitly bind a listener to + a namespace different from the default one. Please refer to your operating + system's documentation to find more details about network namespaces. + +nice <nice> + Sets the 'niceness' of connections initiated from the socket. Value must be + in the range -1024..1024 inclusive, and defaults to zero. Positive values + means that such connections are more friendly to others and easily offer + their place in the scheduler. On the opposite, negative values mean that + connections want to run with a higher priority than others. The difference + only happens under high loads when the system is close to saturation. + Negative values are appropriate for low-latency or administration services, + and high values are generally recommended for CPU intensive tasks such as SSL + processing or bulk transfers which are less sensible to latency. For example, + it may make sense to use a positive value for an SMTP socket and a negative + one for an RDP socket. + +no-ca-names + This setting is only available when support for OpenSSL was built in. It + prevents from send CA names in server hello message when ca-file is used. + Use "ca-verify-file" instead of "ca-file" with "no-ca-names". + +no-sslv3 + This setting is only available when support for OpenSSL was built in. It + disables support for SSLv3 on any sockets instantiated from the listener when + SSL is supported. Note that SSLv2 is forced disabled in the code and cannot + be enabled using any configuration option. This option is also available on + global statement "ssl-default-bind-options". Use "ssl-min-ver" and + "ssl-max-ver" instead. + +no-tls-tickets + This setting is only available when support for OpenSSL was built in. It + disables the stateless session resumption (RFC 5077 TLS Ticket + extension) and force to use stateful session resumption. Stateless + session resumption is more expensive in CPU usage. This option is also + available on global statement "ssl-default-bind-options". + The TLS ticket mechanism is only used up to TLS 1.2. + Forward Secrecy is compromised with TLS tickets, unless ticket keys + are periodically rotated (via reload or by using "tls-ticket-keys"). + +no-tlsv10 + This setting is only available when support for OpenSSL was built in. It + disables support for TLSv1.0 on any sockets instantiated from the listener + when SSL is supported. Note that SSLv2 is forced disabled in the code and + cannot be enabled using any configuration option. This option is also + available on global statement "ssl-default-bind-options". Use "ssl-min-ver" + and "ssl-max-ver" instead. + +no-tlsv11 + This setting is only available when support for OpenSSL was built in. It + disables support for TLSv1.1 on any sockets instantiated from the listener + when SSL is supported. Note that SSLv2 is forced disabled in the code and + cannot be enabled using any configuration option. This option is also + available on global statement "ssl-default-bind-options". Use "ssl-min-ver" + and "ssl-max-ver" instead. + +no-tlsv12 + This setting is only available when support for OpenSSL was built in. It + disables support for TLSv1.2 on any sockets instantiated from the listener + when SSL is supported. Note that SSLv2 is forced disabled in the code and + cannot be enabled using any configuration option. This option is also + available on global statement "ssl-default-bind-options". Use "ssl-min-ver" + and "ssl-max-ver" instead. + +no-tlsv13 + This setting is only available when support for OpenSSL was built in. It + disables support for TLSv1.3 on any sockets instantiated from the listener + when SSL is supported. Note that SSLv2 is forced disabled in the code and + cannot be enabled using any configuration option. This option is also + available on global statement "ssl-default-bind-options". Use "ssl-min-ver" + and "ssl-max-ver" instead. + +npn <protocols> + This enables the NPN TLS extension and advertises the specified protocol list + as supported on top of NPN. The protocol list consists in a comma-delimited + list of protocol names, for instance: "http/1.1,http/1.0" (without quotes). + This requires that the SSL library is built with support for TLS extensions + enabled (check with haproxy -vv). Note that the NPN extension has been + replaced with the ALPN extension (see the "alpn" keyword), though this one is + only available starting with OpenSSL 1.0.2. If HTTP/2 is desired on an older + version of OpenSSL, NPN might still be used as most clients still support it + at the time of writing this. It is possible to enable both NPN and ALPN + though it probably doesn't make any sense out of testing. + +prefer-client-ciphers + Use the client's preference when selecting the cipher suite, by default + the server's preference is enforced. This option is also available on + global statement "ssl-default-bind-options". + Note that with OpenSSL >= 1.1.1 ChaCha20-Poly1305 is reprioritized anyway + (without setting this option), if a ChaCha20-Poly1305 cipher is at the top of + the client cipher list. + +process <process-set>[/<thread-set>] + This restricts the list of threads on which this listener is allowed to run. + It does not enforce any of them but eliminates those which do not match. Note + that only process number 1 is permitted. If a thread set is specified, it + limits the threads allowed to process incoming connections for this listener. + For the unlikely case where several ranges are needed, this directive may be + repeated. <process-set> and <thread-set> must use the format + + all | odd | even | number[-[number]] + + Ranges can be partially defined. The higher bound can be omitted. In such a + case, it is replaced by the corresponding maximum value. The main purpose is + to have multiple bind lines sharing the same IP:port but not the same thread + in a listener, so that the system can distribute the incoming connections + into multiple queues, bypassing haproxy's internal queue load balancing. + Currently Linux 3.9 and above is known for supporting this. + + This directive is deprecated in favor of the more suited "thread" directive + below, and will be removed in 2.7. + +proto <name> + Forces the multiplexer's protocol to use for the incoming connections. It + must be compatible with the mode of the frontend (TCP or HTTP). It must also + be usable on the frontend side. The list of available protocols is reported + in haproxy -vv. The protocols properties are reported : the mode (TCP/HTTP), + the side (FE/BE), the mux name and its flags. + + Some protocols are subject to the head-of-line blocking on server side + (flag=HOL_RISK). Finally some protocols don't support upgrades (flag=NO_UPG). + The HTX compatibility is also reported (flag=HTX). + + Here are the protocols that may be used as argument to a "proto" directive on + a bind line : + + h2 : mode=HTTP side=FE|BE mux=H2 flags=HTX|HOL_RISK|NO_UPG + h1 : mode=HTTP side=FE|BE mux=H1 flags=HTX|NO_UPG + none : mode=TCP side=FE|BE mux=PASS flags=NO_UPG + + Idea behind this option is to bypass the selection of the best multiplexer's + protocol for all connections instantiated from this listening socket. For + instance, it is possible to force the http/2 on clear TCP by specifying "proto + h2" on the bind line. + +quic-cc-algo [ cubic | newreno ] + Warning: QUIC support in HAProxy is currently experimental. Configuration may + + This is a QUIC specific setting to select the congestion control algorithm + for any connection attempts to the configured QUIC listeners. They are similar + to those used by TCP. + + Default value: cubic + +quic-force-retry + Warning: QUIC support in HAProxy is currently experimental. Configuration may + change without deprecation in the future. + + This is a QUIC specific setting which forces the use of the QUIC Retry feature + for all the connection attempts to the configured QUIC listeners. It consists + in veryfying the peers are able to receive packets at the transport address + they used to initiate a new connection, sending them a Retry packet which + contains a token. This token must be sent back to the Retry packet sender, + this latter being the only one to be able to validate the token. Note that QUIC + Retry will always be used even if a Retry threshold was set (see + "tune.quic.retry-threshold" setting). + + This setting requires the cluster secret to be set or else an error will be + reported on startup (see "cluster-secret"). + + See https://www.rfc-editor.org/rfc/rfc9000.html#section-8.1.2 for more + information about QUIC retry. + +shards <number> | by-thread + In multi-threaded mode, on operating systems supporting multiple listeners on + the same IP:port, this will automatically create this number of multiple + identical listeners for the same line, all bound to a fair share of the number + of the threads attached to this listener. This can sometimes be useful when + using very large thread counts where the in-kernel locking on a single socket + starts to cause a significant overhead. In this case the incoming traffic is + distributed over multiple sockets and the contention is reduced. Note that + doing this can easily increase the CPU usage by making more threads work a + little bit. + + If the number of shards is higher than the number of available threads, it + will automatically be trimmed to the number of threads (i.e. one shard per + thread). The special "by-thread" value also creates as many shards as there + are threads on the "bind" line. Since the system will evenly distribute the + incoming traffic between all these shards, it is important that this number + is an integral divisor of the number of threads. + +ssl + This setting is only available when support for OpenSSL was built in. It + enables SSL deciphering on connections instantiated from this listener. A + certificate is necessary (see "crt" above). All contents in the buffers will + appear in clear text, so that ACLs and HTTP processing will only have access + to deciphered contents. SSLv3 is disabled per default, use "ssl-min-ver SSLv3" + to enable it. + +ssl-max-ver [ SSLv3 | TLSv1.0 | TLSv1.1 | TLSv1.2 | TLSv1.3 ] + This option enforces use of <version> or lower on SSL connections instantiated + from this listener. Using this setting without "ssl-min-ver" can be + ambiguous because the default ssl-min-ver value could change in future HAProxy + versions. This option is also available on global statement + "ssl-default-bind-options". See also "ssl-min-ver". + +ssl-min-ver [ SSLv3 | TLSv1.0 | TLSv1.1 | TLSv1.2 | TLSv1.3 ] + This option enforces use of <version> or upper on SSL connections + instantiated from this listener. The default value is "TLSv1.2". This option + is also available on global statement "ssl-default-bind-options". + See also "ssl-max-ver". + +strict-sni + This setting is only available when support for OpenSSL was built in. The + SSL/TLS negotiation is allow only if the client provided an SNI which match + a certificate. The default certificate is not used. + See the "crt" option for more information. + +tcp-ut <delay> + Sets the TCP User Timeout for all incoming connections instantiated from this + listening socket. This option is available on Linux since version 2.6.37. It + allows HAProxy to configure a timeout for sockets which contain data not + receiving an acknowledgment for the configured delay. This is especially + useful on long-lived connections experiencing long idle periods such as + remote terminals or database connection pools, where the client and server + timeouts must remain high to allow a long period of idle, but where it is + important to detect that the client has disappeared in order to release all + resources associated with its connection (and the server's session). The + argument is a delay expressed in milliseconds by default. This only works + for regular TCP connections, and is ignored for other protocols. + +tfo + Is an optional keyword which is supported only on Linux kernels >= 3.7. It + enables TCP Fast Open on the listening socket, which means that clients which + support this feature will be able to send a request and receive a response + during the 3-way handshake starting from second connection, thus saving one + round-trip after the first connection. This only makes sense with protocols + that use high connection rates and where each round trip matters. This can + possibly cause issues with many firewalls which do not accept data on SYN + packets, so this option should only be enabled once well tested. This option + is only supported on TCPv4/TCPv6 sockets and ignored by other ones. You may + need to build HAProxy with USE_TFO=1 if your libc doesn't define + TCP_FASTOPEN. + +thread [<thread-group>/]<thread-set> + This restricts the list of threads on which this listener is allowed to run. + It does not enforce any of them but eliminates those which do not match. It + limits the threads allowed to process incoming connections for this listener. + + There are two numbering schemes. By default, thread numbers are absolute in + the process, comprised between 1 and the value specified in global.nbthread. + When thread groups are enabled, the number of a single desired thread group + (starting at 1) may be specified before a slash ('/') before the thread + range. In this case, the thread numbers in the range are relative to the + thread group instead, and start at 1 for each thread group. Absolute and + relative thread numbers may be used interchangeably but they must not be + mixed on a single "bind" line, as those not set will be resolved at the end + of the parsing. + + For the unlikely case where several ranges are needed, this directive may be + repeated. It is not permitted to use different thread groups even when using + multiple directives. The <thread-set> specification must use the format: + + all | odd | even | number[-[number]] + + Ranges can be partially defined. The higher bound can be omitted. In such a + case, it is replaced by the corresponding maximum value. The main purpose is + to have multiple bind lines sharing the same IP:port but not the same thread + in a listener, so that the system can distribute the incoming connections + into multiple queues, bypassing haproxy's internal queue load balancing. + Currently Linux 3.9 and above is known for supporting this. + +tls-ticket-keys <keyfile> + Sets the TLS ticket keys file to load the keys from. The keys need to be 48 + or 80 bytes long, depending if aes128 or aes256 is used, encoded with base64 + with one line per key (ex. openssl rand 80 | openssl base64 -A | xargs echo). + The first key determines the key length used for next keys: you can't mix + aes128 and aes256 keys. Number of keys is specified by the TLS_TICKETS_NO + build option (default 3) and at least as many keys need to be present in + the file. Last TLS_TICKETS_NO keys will be used for decryption and the + penultimate one for encryption. This enables easy key rotation by just + appending new key to the file and reloading the process. Keys must be + periodically rotated (ex. every 12h) or Perfect Forward Secrecy is + compromised. It is also a good idea to keep the keys off any permanent + storage such as hard drives (hint: use tmpfs and don't swap those files). + Lifetime hint can be changed using tune.ssl.timeout. + +transparent + Is an optional keyword which is supported only on certain Linux kernels. It + indicates that the addresses will be bound even if they do not belong to the + local machine, and that packets targeting any of these addresses will be + intercepted just as if the addresses were locally configured. This normally + requires that IP forwarding is enabled. Caution! do not use this with the + default address '*', as it would redirect any traffic for the specified port. + This keyword is available only when HAProxy is built with USE_LINUX_TPROXY=1. + This parameter is only compatible with TCPv4 and TCPv6 sockets, depending on + kernel version. Some distribution kernels include backports of the feature, + so check for support with your vendor. + +v4v6 + Is an optional keyword which is supported only on most recent systems + including Linux kernels >= 2.4.21. It is used to bind a socket to both IPv4 + and IPv6 when it uses the default address. Doing so is sometimes necessary + on systems which bind to IPv6 only by default. It has no effect on non-IPv6 + sockets, and is overridden by the "v6only" option. + +v6only + Is an optional keyword which is supported only on most recent systems + including Linux kernels >= 2.4.21. It is used to bind a socket to IPv6 only + when it uses the default address. Doing so is sometimes preferred to doing it + system-wide as it is per-listener. It has no effect on non-IPv6 sockets and + has precedence over the "v4v6" option. + +uid <uid> + Sets the owner of the UNIX sockets to the designated system uid. It can also + be set by default in the global section's "unix-bind" statement. Note that + some platforms simply ignore this. This setting is equivalent to the "user" + setting except that the user numeric ID is used instead of its name. This + setting is ignored by non UNIX sockets. + +user <user> + Sets the owner of the UNIX sockets to the designated system user. It can also + be set by default in the global section's "unix-bind" statement. Note that + some platforms simply ignore this. This setting is equivalent to the "uid" + setting except that the user name is used instead of its uid. This setting is + ignored by non UNIX sockets. + +verify [none|optional|required] + This setting is only available when support for OpenSSL was built in. If set + to 'none', client certificate is not requested. This is the default. In other + cases, a client certificate is requested. If the client does not provide a + certificate after the request and if 'verify' is set to 'required', then the + handshake is aborted, while it would have succeeded if set to 'optional'. The + certificate provided by the client is always verified using CAs from + 'ca-file' and optional CRLs from 'crl-file'. On verify failure the handshake + is aborted, regardless of the 'verify' option, unless the error code exactly + matches one of those listed with 'ca-ignore-err' or 'crt-ignore-err'. + +5.2. Server and default-server options +------------------------------------ + +The "server" and "default-server" keywords support a certain number of settings +which are all passed as arguments on the server line. The order in which those +arguments appear does not count, and they are all optional. Some of those +settings are single words (booleans) while others expect one or several values +after them. In this case, the values must immediately follow the setting name. +Except default-server, all those settings must be specified after the server's +address if they are used: + + server <name> <address>[:port] [settings ...] + default-server [settings ...] + +Note that all these settings are supported both by "server" and "default-server" +keywords, except "id" which is only supported by "server". + +The currently supported settings are the following ones. + +addr <ipv4|ipv6> + Using the "addr" parameter, it becomes possible to use a different IP address + to send health-checks or to probe the agent-check. On some servers, it may be + desirable to dedicate an IP address to specific component able to perform + complex tests which are more suitable to health-checks than the application. + This parameter is ignored if the "check" parameter is not set. See also the + "port" parameter. + +agent-check + Enable an auxiliary agent check which is run independently of a regular + health check. An agent health check is performed by making a TCP connection + to the port set by the "agent-port" parameter and reading an ASCII string + terminated by the first '\r' or '\n' met. The string is made of a series of + words delimited by spaces, tabs or commas in any order, each consisting of : + + - An ASCII representation of a positive integer percentage, e.g. "75%". + Values in this format will set the weight proportional to the initial + weight of a server as configured when HAProxy starts. Note that a zero + weight is reported on the stats page as "DRAIN" since it has the same + effect on the server (it's removed from the LB farm). + + - The string "maxconn:" followed by an integer (no space between). Values + in this format will set the maxconn of a server. The maximum number of + connections advertised needs to be multiplied by the number of load + balancers and different backends that use this health check to get the + total number of connections the server might receive. Example: maxconn:30 + + - The word "ready". This will turn the server's administrative state to the + READY mode, thus canceling any DRAIN or MAINT state + + - The word "drain". This will turn the server's administrative state to the + DRAIN mode, thus it will not accept any new connections other than those + that are accepted via persistence. + + - The word "maint". This will turn the server's administrative state to the + MAINT mode, thus it will not accept any new connections at all, and health + checks will be stopped. + + - The words "down", "fail", or "stopped", optionally followed by a + description string after a sharp ('#'). All of these mark the server's + operating state as DOWN, but since the word itself is reported on the stats + page, the difference allows an administrator to know if the situation was + expected or not : the service may intentionally be stopped, may appear up + but fail some validity tests, or may be seen as down (e.g. missing process, + or port not responding). + + - The word "up" sets back the server's operating state as UP if health checks + also report that the service is accessible. + + Parameters which are not advertised by the agent are not changed. For + example, an agent might be designed to monitor CPU usage and only report a + relative weight and never interact with the operating status. Similarly, an + agent could be designed as an end-user interface with 3 radio buttons + allowing an administrator to change only the administrative state. However, + it is important to consider that only the agent may revert its own actions, + so if a server is set to DRAIN mode or to DOWN state using the agent, the + agent must implement the other equivalent actions to bring the service into + operations again. + + Failure to connect to the agent is not considered an error as connectivity + is tested by the regular health check which is enabled by the "check" + parameter. Warning though, it is not a good idea to stop an agent after it + reports "down", since only an agent reporting "up" will be able to turn the + server up again. Note that the CLI on the Unix stats socket is also able to + force an agent's result in order to work around a bogus agent if needed. + + Requires the "agent-port" parameter to be set. See also the "agent-inter" + and "no-agent-check" parameters. + +agent-send <string> + If this option is specified, HAProxy will send the given string (verbatim) + to the agent server upon connection. You could, for example, encode + the backend name into this string, which would enable your agent to send + different responses based on the backend. Make sure to include a '\n' if + you want to terminate your request with a newline. + +agent-inter <delay> + The "agent-inter" parameter sets the interval between two agent checks + to <delay> milliseconds. If left unspecified, the delay defaults to 2000 ms. + + Just as with every other time-based parameter, it may be entered in any + other explicit unit among { us, ms, s, m, h, d }. The "agent-inter" + parameter also serves as a timeout for agent checks "timeout check" is + not set. In order to reduce "resonance" effects when multiple servers are + hosted on the same hardware, the agent and health checks of all servers + are started with a small time offset between them. It is also possible to + add some random noise in the agent and health checks interval using the + global "spread-checks" keyword. This makes sense for instance when a lot + of backends use the same servers. + + See also the "agent-check" and "agent-port" parameters. + +agent-addr <addr> + The "agent-addr" parameter sets address for agent check. + + You can offload agent-check to another target, so you can make single place + managing status and weights of servers defined in HAProxy in case you can't + make self-aware and self-managing services. You can specify both IP or + hostname, it will be resolved. + +agent-port <port> + The "agent-port" parameter sets the TCP port used for agent checks. + + See also the "agent-check" and "agent-inter" parameters. + +allow-0rtt + Allow sending early data to the server when using TLS 1.3. + Note that early data will be sent only if the client used early data, or + if the backend uses "retry-on" with the "0rtt-rejected" keyword. + +alpn <protocols> + This enables the TLS ALPN extension and advertises the specified protocol + list as supported on top of ALPN. The protocol list consists in a comma- + delimited list of protocol names, for instance: "http/1.1,http/1.0" (without + quotes). This requires that the SSL library is built with support for TLS + extensions enabled (check with haproxy -vv). The ALPN extension replaces the + initial NPN extension. ALPN is required to connect to HTTP/2 servers. + Versions of OpenSSL prior to 1.0.2 didn't support ALPN and only supposed the + now obsolete NPN extension. + If both HTTP/2 and HTTP/1.1 are expected to be supported, both versions can + be advertised, in order of preference, like below : + + server 127.0.0.1:443 ssl crt pub.pem alpn h2,http/1.1 + + See also "ws" to use an alternative ALPN for websocket streams. + +backup + When "backup" is present on a server line, the server is only used in load + balancing when all other non-backup servers are unavailable. Requests coming + with a persistence cookie referencing the server will always be served + though. By default, only the first operational backup server is used, unless + the "allbackups" option is set in the backend. See also the "no-backup" and + "allbackups" options. + +ca-file <cafile> + This setting is only available when support for OpenSSL was built in. It + designates a PEM file from which to load CA certificates used to verify + server's certificate. It is possible to load a directory containing multiple + CAs, in this case HAProxy will try to load every ".pem", ".crt", ".cer", and + .crl" available in the directory, files starting with a dot are ignored. + + In order to use the trusted CAs of your system, the "@system-ca" parameter + could be used in place of the cafile. The location of this directory could be + overwritten by setting the SSL_CERT_DIR environment variable. + +check + This option enables health checks on a server: + - when not set, no health checking is performed, and the server is always + considered available. + - when set and no other check method is configured, the server is considered + available when a connection can be established at the highest configured + transport layer. This means TCP by default, or SSL/TLS when "ssl" or + "check-ssl" are set, both possibly combined with connection prefixes such + as a PROXY protocol header when "send-proxy" or "check-send-proxy" are + set. This behavior is slightly different for dynamic servers, read the + following paragraphs for more details. + - when set and an application-level health check is defined, the + application-level exchanges are performed on top of the configured + transport layer and the server is considered available if all of the + exchanges succeed. + + By default, health checks are performed on the same address and port as + configured on the server, using the same encapsulation parameters (SSL/TLS, + proxy-protocol header, etc... ). It is possible to change the destination + address using "addr" and the port using "port". When done, it is assumed the + server isn't checked on the service port, and configured encapsulation + parameters are not reused. One must explicitly set "check-send-proxy" to send + connection headers, "check-ssl" to use SSL/TLS. + + Note that the implicit configuration of ssl and PROXY protocol is not + performed for dynamic servers. In this case, it is required to explicitly + use "check-ssl" and "check-send-proxy" when wanted, even if the check port is + not overridden. + + When "sni" or "alpn" are set on the server line, their value is not used for + health checks and one must use "check-sni" or "check-alpn". + + The default source address for health check traffic is the same as the one + defined in the backend. It can be changed with the "source" keyword. + + The interval between checks can be set using the "inter" keyword, and the + "rise" and "fall" keywords can be used to define how many successful or + failed health checks are required to flag a server available or not + available. + + Optional application-level health checks can be configured with "option + httpchk", "option mysql-check" "option smtpchk", "option pgsql-check", + "option ldap-check", or "option redis-check". + + Example: + # simple tcp check + backend foo + server s1 192.168.0.1:80 check + # this does a tcp connect + tls handshake + backend foo + server s1 192.168.0.1:443 ssl check + # simple tcp check is enough for check success + backend foo + option tcp-check + tcp-check connect + server s1 192.168.0.1:443 ssl check + +check-send-proxy + This option forces emission of a PROXY protocol line with outgoing health + checks, regardless of whether the server uses send-proxy or not for the + normal traffic. By default, the PROXY protocol is enabled for health checks + if it is already enabled for normal traffic and if no "port" nor "addr" + directive is present. However, if such a directive is present, the + "check-send-proxy" option needs to be used to force the use of the + protocol. See also the "send-proxy" option for more information. + +check-alpn <protocols> + Defines which protocols to advertise with ALPN. The protocol list consists in + a comma-delimited list of protocol names, for instance: "http/1.1,http/1.0" + (without quotes). If it is not set, the server ALPN is used. + +check-proto <name> + Forces the multiplexer's protocol to use for the server's health-check + connections. It must be compatible with the health-check type (TCP or + HTTP). It must also be usable on the backend side. The list of available + protocols is reported in haproxy -vv. The protocols properties are + reported : the mode (TCP/HTTP), the side (FE/BE), the mux name and its flags. + + Some protocols are subject to the head-of-line blocking on server side + (flag=HOL_RISK). Finally some protocols don't support upgrades (flag=NO_UPG). + The HTX compatibility is also reported (flag=HTX). + + Here are the protocols that may be used as argument to a "check-proto" + directive on a server line: + + h2 : mode=HTTP side=FE|BE mux=H2 flags=HTX|HOL_RISK|NO_UPG + fcgi : mode=HTTP side=BE mux=FCGI flags=HTX|HOL_RISK|NO_UPG + h1 : mode=HTTP side=FE|BE mux=H1 flags=HTX|NO_UPG + none : mode=TCP side=FE|BE mux=PASS flags=NO_UPG + + Idea behind this option is to bypass the selection of the best multiplexer's + protocol for health-check connections established to this server. + If not defined, the server one will be used, if set. + +check-sni <sni> + This option allows you to specify the SNI to be used when doing health checks + over SSL. It is only possible to use a string to set <sni>. If you want to + set a SNI for proxied traffic, see "sni". + +check-ssl + This option forces encryption of all health checks over SSL, regardless of + whether the server uses SSL or not for the normal traffic. This is generally + used when an explicit "port" or "addr" directive is specified and SSL health + checks are not inherited. It is important to understand that this option + inserts an SSL transport layer below the checks, so that a simple TCP connect + check becomes an SSL connect, which replaces the old ssl-hello-chk. The most + common use is to send HTTPS checks by combining "httpchk" with SSL checks. + All SSL settings are common to health checks and traffic (e.g. ciphers). + See the "ssl" option for more information and "no-check-ssl" to disable + this option. + +check-via-socks4 + This option enables outgoing health checks using upstream socks4 proxy. By + default, the health checks won't go through socks tunnel even it was enabled + for normal traffic. + +ciphers <ciphers> + This setting is only available when support for OpenSSL was built in. This + option sets the string describing the list of cipher algorithms that is + negotiated during the SSL/TLS handshake with the server. The format of the + string is defined in "man 1 ciphers" from OpenSSL man pages. For background + information and recommendations see e.g. + (https://wiki.mozilla.org/Security/Server_Side_TLS) and + (https://mozilla.github.io/server-side-tls/ssl-config-generator/). For TLSv1.3 + cipher configuration, please check the "ciphersuites" keyword. + +ciphersuites <ciphersuites> + This setting is only available when support for OpenSSL was built in and + OpenSSL 1.1.1 or later was used to build HAProxy. This option sets the string + describing the list of cipher algorithms that is negotiated during the TLS + 1.3 handshake with the server. The format of the string is defined in + "man 1 ciphers" from OpenSSL man pages under the "ciphersuites" section. + For cipher configuration for TLSv1.2 and earlier, please check the "ciphers" + keyword. + +cookie <value> + The "cookie" parameter sets the cookie value assigned to the server to + <value>. This value will be checked in incoming requests, and the first + operational server possessing the same value will be selected. In return, in + cookie insertion or rewrite modes, this value will be assigned to the cookie + sent to the client. There is nothing wrong in having several servers sharing + the same cookie value, and it is in fact somewhat common between normal and + backup servers. See also the "cookie" keyword in backend section. + +crl-file <crlfile> + This setting is only available when support for OpenSSL was built in. It + designates a PEM file from which to load certificate revocation list used + to verify server's certificate. + +crt <cert> + This setting is only available when support for OpenSSL was built in. + It designates a PEM file from which to load both a certificate and the + associated private key. This file can be built by concatenating both PEM + files into one. This certificate will be sent if the server send a client + certificate request. + + If the file does not contain a private key, HAProxy will try to load the key + at the same path suffixed by a ".key" (provided the "ssl-load-extra-files" + option is set accordingly). + +disabled + The "disabled" keyword starts the server in the "disabled" state. That means + that it is marked down in maintenance mode, and no connection other than the + ones allowed by persist mode will reach it. It is very well suited to setup + new servers, because normal traffic will never reach them, while it is still + possible to test the service by making use of the force-persist mechanism. + See also "enabled" setting. + +enabled + This option may be used as 'server' setting to reset any 'disabled' + setting which would have been inherited from 'default-server' directive as + default value. + It may also be used as 'default-server' setting to reset any previous + 'default-server' 'disabled' setting. + +error-limit <count> + If health observing is enabled, the "error-limit" parameter specifies the + number of consecutive errors that triggers event selected by the "on-error" + option. By default it is set to 10 consecutive errors. + + See also the "check", "error-limit" and "on-error". + +fall <count> + The "fall" parameter states that a server will be considered as dead after + <count> consecutive unsuccessful health checks. This value defaults to 3 if + unspecified. See also the "check", "inter" and "rise" parameters. + +force-sslv3 + This option enforces use of SSLv3 only when SSL is used to communicate with + the server. SSLv3 is generally less expensive than the TLS counterparts for + high connection rates. This option is also available on global statement + "ssl-default-server-options". See also "ssl-min-ver" and ssl-max-ver". + +force-tlsv10 + This option enforces use of TLSv1.0 only when SSL is used to communicate with + the server. This option is also available on global statement + "ssl-default-server-options". See also "ssl-min-ver" and ssl-max-ver". + +force-tlsv11 + This option enforces use of TLSv1.1 only when SSL is used to communicate with + the server. This option is also available on global statement + "ssl-default-server-options". See also "ssl-min-ver" and ssl-max-ver". + +force-tlsv12 + This option enforces use of TLSv1.2 only when SSL is used to communicate with + the server. This option is also available on global statement + "ssl-default-server-options". See also "ssl-min-ver" and ssl-max-ver". + +force-tlsv13 + This option enforces use of TLSv1.3 only when SSL is used to communicate with + the server. This option is also available on global statement + "ssl-default-server-options". See also "ssl-min-ver" and ssl-max-ver". + +id <value> + Set a persistent ID for the server. This ID must be positive and unique for + the proxy. An unused ID will automatically be assigned if unset. The first + assigned value will be 1. This ID is currently only returned in statistics. + +init-addr {last | libc | none | <ip>},[...]* + Indicate in what order the server's address should be resolved upon startup + if it uses an FQDN. Attempts are made to resolve the address by applying in + turn each of the methods mentioned in the comma-delimited list. The first + method which succeeds is used. If the end of the list is reached without + finding a working method, an error is thrown. Method "last" suggests to pick + the address which appears in the state file (see "server-state-file"). Method + "libc" uses the libc's internal resolver (gethostbyname() or getaddrinfo() + depending on the operating system and build options). Method "none" + specifically indicates that the server should start without any valid IP + address in a down state. It can be useful to ignore some DNS issues upon + startup, waiting for the situation to get fixed later. Finally, an IP address + (IPv4 or IPv6) may be provided. It can be the currently known address of the + server (e.g. filled by a configuration generator), or the address of a dummy + server used to catch old sessions and present them with a decent error + message for example. When the "first" load balancing algorithm is used, this + IP address could point to a fake server used to trigger the creation of new + instances on the fly. This option defaults to "last,libc" indicating that the + previous address found in the state file (if any) is used first, otherwise + the libc's resolver is used. This ensures continued compatibility with the + historic behavior. + + Example: + defaults + # never fail on address resolution + default-server init-addr last,libc,none + +inter <delay> +fastinter <delay> +downinter <delay> + The "inter" parameter sets the interval between two consecutive health checks + to <delay> milliseconds. If left unspecified, the delay defaults to 2000 ms. + It is also possible to use "fastinter" and "downinter" to optimize delays + between checks depending on the server state : + + Server state | Interval used + ----------------------------------------+---------------------------------- + UP 100% (non-transitional) | "inter" + ----------------------------------------+---------------------------------- + Transitionally UP (going down "fall"), | "fastinter" if set, + Transitionally DOWN (going up "rise"), | "inter" otherwise. + or yet unchecked. | + ----------------------------------------+---------------------------------- + DOWN 100% (non-transitional) | "downinter" if set, + | "inter" otherwise. + ----------------------------------------+---------------------------------- + + Just as with every other time-based parameter, they can be entered in any + other explicit unit among { us, ms, s, m, h, d }. The "inter" parameter also + serves as a timeout for health checks sent to servers if "timeout check" is + not set. In order to reduce "resonance" effects when multiple servers are + hosted on the same hardware, the agent and health checks of all servers + are started with a small time offset between them. It is also possible to + add some random noise in the agent and health checks interval using the + global "spread-checks" keyword. This makes sense for instance when a lot + of backends use the same servers. + +log-proto <logproto> + The "log-proto" specifies the protocol used to forward event messages to + a server configured in a ring section. Possible values are "legacy" + and "octet-count" corresponding respectively to "Non-transparent-framing" + and "Octet counting" in rfc6587. "legacy" is the default. + +maxconn <maxconn> + The "maxconn" parameter specifies the maximal number of concurrent + connections that will be sent to this server. If the number of incoming + concurrent connections goes higher than this value, they will be queued, + waiting for a slot to be released. This parameter is very important as it can + save fragile servers from going down under extreme loads. If a "minconn" + parameter is specified, the limit becomes dynamic. The default value is "0" + which means unlimited. See also the "minconn" and "maxqueue" parameters, and + the backend's "fullconn" keyword. + + In HTTP mode this parameter limits the number of concurrent requests instead + of the number of connections. Multiple requests might be multiplexed over a + single TCP connection to the server. As an example if you specify a maxconn + of 50 you might see between 1 and 50 actual server connections, but no more + than 50 concurrent requests. + +maxqueue <maxqueue> + The "maxqueue" parameter specifies the maximal number of connections which + will wait in the queue for this server. If this limit is reached, next + requests will be redispatched to other servers instead of indefinitely + waiting to be served. This will break persistence but may allow people to + quickly re-log in when the server they try to connect to is dying. Some load + balancing algorithms such as leastconn take this into account and accept to + add requests into a server's queue up to this value if it is explicitly set + to a value greater than zero, which often allows to better smooth the load + when dealing with single-digit maxconn values. The default value is "0" which + means the queue is unlimited. See also the "maxconn" and "minconn" parameters + and "balance leastconn". + +max-reuse <count> + The "max-reuse" argument indicates the HTTP connection processors that they + should not reuse a server connection more than this number of times to send + new requests. Permitted values are -1 (the default), which disables this + limit, or any positive value. Value zero will effectively disable keep-alive. + This is only used to work around certain server bugs which cause them to leak + resources over time. The argument is not necessarily respected by the lower + layers as there might be technical limitations making it impossible to + enforce. At least HTTP/2 connections to servers will respect it. + +minconn <minconn> + When the "minconn" parameter is set, the maxconn limit becomes a dynamic + limit following the backend's load. The server will always accept at least + <minconn> connections, never more than <maxconn>, and the limit will be on + the ramp between both values when the backend has less than <fullconn> + concurrent connections. This makes it possible to limit the load on the + server during normal loads, but push it further for important loads without + overloading the server during exceptional loads. See also the "maxconn" + and "maxqueue" parameters, as well as the "fullconn" backend keyword. + +namespace <name> + On Linux, it is possible to specify which network namespace a socket will + belong to. This directive makes it possible to explicitly bind a server to + a namespace different from the default one. Please refer to your operating + system's documentation to find more details about network namespaces. + +no-agent-check + This option may be used as "server" setting to reset any "agent-check" + setting which would have been inherited from "default-server" directive as + default value. + It may also be used as "default-server" setting to reset any previous + "default-server" "agent-check" setting. + +no-backup + This option may be used as "server" setting to reset any "backup" + setting which would have been inherited from "default-server" directive as + default value. + It may also be used as "default-server" setting to reset any previous + "default-server" "backup" setting. + +no-check + This option may be used as "server" setting to reset any "check" + setting which would have been inherited from "default-server" directive as + default value. + It may also be used as "default-server" setting to reset any previous + "default-server" "check" setting. + +no-check-ssl + This option may be used as "server" setting to reset any "check-ssl" + setting which would have been inherited from "default-server" directive as + default value. + It may also be used as "default-server" setting to reset any previous + "default-server" "check-ssl" setting. + +no-send-proxy + This option may be used as "server" setting to reset any "send-proxy" + setting which would have been inherited from "default-server" directive as + default value. + It may also be used as "default-server" setting to reset any previous + "default-server" "send-proxy" setting. + +no-send-proxy-v2 + This option may be used as "server" setting to reset any "send-proxy-v2" + setting which would have been inherited from "default-server" directive as + default value. + It may also be used as "default-server" setting to reset any previous + "default-server" "send-proxy-v2" setting. + +no-send-proxy-v2-ssl + This option may be used as "server" setting to reset any "send-proxy-v2-ssl" + setting which would have been inherited from "default-server" directive as + default value. + It may also be used as "default-server" setting to reset any previous + "default-server" "send-proxy-v2-ssl" setting. + +no-send-proxy-v2-ssl-cn + This option may be used as "server" setting to reset any "send-proxy-v2-ssl-cn" + setting which would have been inherited from "default-server" directive as + default value. + It may also be used as "default-server" setting to reset any previous + "default-server" "send-proxy-v2-ssl-cn" setting. + +no-ssl + This option may be used as "server" setting to reset any "ssl" + setting which would have been inherited from "default-server" directive as + default value. + It may also be used as "default-server" setting to reset any previous + "default-server" "ssl" setting. + + Note that using `default-server ssl` setting and `no-ssl` on server will + however init SSL connection, so it can be later be enabled through the + runtime API: see `set server` commands in management doc. + +no-ssl-reuse + This option disables SSL session reuse when SSL is used to communicate with + the server. It will force the server to perform a full handshake for every + new connection. It's probably only useful for benchmarking, troubleshooting, + and for paranoid users. + +no-sslv3 + This option disables support for SSLv3 when SSL is used to communicate with + the server. Note that SSLv2 is disabled in the code and cannot be enabled + using any configuration option. Use "ssl-min-ver" and "ssl-max-ver" instead. + + Supported in default-server: No + +no-tls-tickets + This setting is only available when support for OpenSSL was built in. It + disables the stateless session resumption (RFC 5077 TLS Ticket + extension) and force to use stateful session resumption. Stateless + session resumption is more expensive in CPU usage for servers. This option + is also available on global statement "ssl-default-server-options". + The TLS ticket mechanism is only used up to TLS 1.2. + Forward Secrecy is compromised with TLS tickets, unless ticket keys + are periodically rotated (via reload or by using "tls-ticket-keys"). + See also "tls-tickets". + +no-tlsv10 + This option disables support for TLSv1.0 when SSL is used to communicate with + the server. Note that SSLv2 is disabled in the code and cannot be enabled + using any configuration option. TLSv1 is more expensive than SSLv3 so it + often makes sense to disable it when communicating with local servers. This + option is also available on global statement "ssl-default-server-options". + Use "ssl-min-ver" and "ssl-max-ver" instead. + + Supported in default-server: No + +no-tlsv11 + This option disables support for TLSv1.1 when SSL is used to communicate with + the server. Note that SSLv2 is disabled in the code and cannot be enabled + using any configuration option. TLSv1 is more expensive than SSLv3 so it + often makes sense to disable it when communicating with local servers. This + option is also available on global statement "ssl-default-server-options". + Use "ssl-min-ver" and "ssl-max-ver" instead. + + Supported in default-server: No + +no-tlsv12 + This option disables support for TLSv1.2 when SSL is used to communicate with + the server. Note that SSLv2 is disabled in the code and cannot be enabled + using any configuration option. TLSv1 is more expensive than SSLv3 so it + often makes sense to disable it when communicating with local servers. This + option is also available on global statement "ssl-default-server-options". + Use "ssl-min-ver" and "ssl-max-ver" instead. + + Supported in default-server: No + +no-tlsv13 + This option disables support for TLSv1.3 when SSL is used to communicate with + the server. Note that SSLv2 is disabled in the code and cannot be enabled + using any configuration option. TLSv1 is more expensive than SSLv3 so it + often makes sense to disable it when communicating with local servers. This + option is also available on global statement "ssl-default-server-options". + Use "ssl-min-ver" and "ssl-max-ver" instead. + + Supported in default-server: No + +no-verifyhost + This option may be used as "server" setting to reset any "verifyhost" + setting which would have been inherited from "default-server" directive as + default value. + It may also be used as "default-server" setting to reset any previous + "default-server" "verifyhost" setting. + +no-tfo + This option may be used as "server" setting to reset any "tfo" + setting which would have been inherited from "default-server" directive as + default value. + It may also be used as "default-server" setting to reset any previous + "default-server" "tfo" setting. + +non-stick + Never add connections allocated to this sever to a stick-table. + This may be used in conjunction with backup to ensure that + stick-table persistence is disabled for backup servers. + +npn <protocols> + This enables the NPN TLS extension and advertises the specified protocol list + as supported on top of NPN. The protocol list consists in a comma-delimited + list of protocol names, for instance: "http/1.1,http/1.0" (without quotes). + This requires that the SSL library is built with support for TLS extensions + enabled (check with haproxy -vv). Note that the NPN extension has been + replaced with the ALPN extension (see the "alpn" keyword), though this one is + only available starting with OpenSSL 1.0.2. + +observe <mode> + This option enables health adjusting based on observing communication with + the server. By default this functionality is disabled and enabling it also + requires to enable health checks. There are two supported modes: "layer4" and + "layer7". In layer4 mode, only successful/unsuccessful tcp connections are + significant. In layer7, which is only allowed for http proxies, responses + received from server are verified, like valid/wrong http code, unparsable + headers, a timeout, etc. Valid status codes include 100 to 499, 501 and 505. + + See also the "check", "on-error" and "error-limit". + +on-error <mode> + Select what should happen when enough consecutive errors are detected. + Currently, four modes are available: + - fastinter: force fastinter + - fail-check: simulate a failed check, also forces fastinter (default) + - sudden-death: simulate a pre-fatal failed health check, one more failed + check will mark a server down, forces fastinter + - mark-down: mark the server immediately down and force fastinter + + See also the "check", "observe" and "error-limit". + +on-marked-down <action> + Modify what occurs when a server is marked down. + Currently one action is available: + - shutdown-sessions: Shutdown peer sessions. When this setting is enabled, + all connections to the server are immediately terminated when the server + goes down. It might be used if the health check detects more complex cases + than a simple connection status, and long timeouts would cause the service + to remain unresponsive for too long a time. For instance, a health check + might detect that a database is stuck and that there's no chance to reuse + existing connections anymore. Connections killed this way are logged with + a 'D' termination code (for "Down"). + + Actions are disabled by default + +on-marked-up <action> + Modify what occurs when a server is marked up. + Currently one action is available: + - shutdown-backup-sessions: Shutdown sessions on all backup servers. This is + done only if the server is not in backup state and if it is not disabled + (it must have an effective weight > 0). This can be used sometimes to force + an active server to take all the traffic back after recovery when dealing + with long sessions (e.g. LDAP, SQL, ...). Doing this can cause more trouble + than it tries to solve (e.g. incomplete transactions), so use this feature + with extreme care. Sessions killed because a server comes up are logged + with an 'U' termination code (for "Up"). + + Actions are disabled by default + +pool-low-conn <max> + Set a low threshold on the number of idling connections for a server, below + which a thread will not try to steal a connection from another thread. This + can be useful to improve CPU usage patterns in scenarios involving many very + fast servers, in order to ensure all threads will keep a few idle connections + all the time instead of letting them accumulate over one thread and migrating + them from thread to thread. Typical values of twice the number of threads + seem to show very good performance already with sub-millisecond response + times. The default is zero, indicating that any idle connection can be used + at any time. It is the recommended setting for normal use. This only applies + to connections that can be shared according to the same principles as those + applying to "http-reuse". In case connection sharing between threads would + be disabled via "tune.idle-pool.shared", it can become very important to use + this setting to make sure each thread always has a few connections, or the + connection reuse rate will decrease as thread count increases. + +pool-max-conn <max> + Set the maximum number of idling connections for a server. -1 means unlimited + connections, 0 means no idle connections. The default is -1. When idle + connections are enabled, orphaned idle connections which do not belong to any + client session anymore are moved to a dedicated pool so that they remain + usable by future clients. This only applies to connections that can be shared + according to the same principles as those applying to "http-reuse". + +pool-purge-delay <delay> + Sets the delay to start purging idle connections. Each <delay> interval, half + of the idle connections are closed. 0 means we don't keep any idle connection. + The default is 5s. + +port <port> + Using the "port" parameter, it becomes possible to use a different port to + send health-checks or to probe the agent-check. On some servers, it may be + desirable to dedicate a port to a specific component able to perform complex + tests which are more suitable to health-checks than the application. It is + common to run a simple script in inetd for instance. This parameter is + ignored if the "check" parameter is not set. See also the "addr" parameter. + +proto <name> + Forces the multiplexer's protocol to use for the outgoing connections to this + server. It must be compatible with the mode of the backend (TCP or HTTP). It + must also be usable on the backend side. The list of available protocols is + reported in haproxy -vv.The protocols properties are reported : the mode + (TCP/HTTP), the side (FE/BE), the mux name and its flags. + + Some protocols are subject to the head-of-line blocking on server side + (flag=HOL_RISK). Finally some protocols don't support upgrades (flag=NO_UPG). + The HTX compatibility is also reported (flag=HTX). + + Here are the protocols that may be used as argument to a "proto" directive on + a server line : + + h2 : mode=HTTP side=FE|BE mux=H2 flags=HTX|HOL_RISK|NO_UPG + fcgi : mode=HTTP side=BE mux=FCGI flags=HTX|HOL_RISK|NO_UPG + h1 : mode=HTTP side=FE|BE mux=H1 flags=HTX|NO_UPG + none : mode=TCP side=FE|BE mux=PASS flags=NO_UPG + + Idea behind this option is to bypass the selection of the best multiplexer's + protocol for all connections established to this server. + + See also "ws" to use an alternative protocol for websocket streams. + +redir <prefix> + The "redir" parameter enables the redirection mode for all GET and HEAD + requests addressing this server. This means that instead of having HAProxy + forward the request to the server, it will send an "HTTP 302" response with + the "Location" header composed of this prefix immediately followed by the + requested URI beginning at the leading '/' of the path component. That means + that no trailing slash should be used after <prefix>. All invalid requests + will be rejected, and all non-GET or HEAD requests will be normally served by + the server. Note that since the response is completely forged, no header + mangling nor cookie insertion is possible in the response. However, cookies in + requests are still analyzed, making this solution completely usable to direct + users to a remote location in case of local disaster. Main use consists in + increasing bandwidth for static servers by having the clients directly + connect to them. Note: never use a relative location here, it would cause a + loop between the client and HAProxy! + + Example : server srv1 192.168.1.1:80 redir http://image1.mydomain.com check + +rise <count> + The "rise" parameter states that a server will be considered as operational + after <count> consecutive successful health checks. This value defaults to 2 + if unspecified. See also the "check", "inter" and "fall" parameters. + +resolve-opts <option>,<option>,... + Comma separated list of options to apply to DNS resolution linked to this + server. + + Available options: + + * allow-dup-ip + By default, HAProxy prevents IP address duplication in a backend when DNS + resolution at runtime is in operation. + That said, for some cases, it makes sense that two servers (in the same + backend, being resolved by the same FQDN) have the same IP address. + For such case, simply enable this option. + This is the opposite of prevent-dup-ip. + + * ignore-weight + Ignore any weight that is set within an SRV record. This is useful when + you would like to control the weights using an alternate method, such as + using an "agent-check" or through the runtime api. + + * prevent-dup-ip + Ensure HAProxy's default behavior is enforced on a server: prevent re-using + an IP address already set to a server in the same backend and sharing the + same fqdn. + This is the opposite of allow-dup-ip. + + Example: + backend b_myapp + default-server init-addr none resolvers dns + server s1 myapp.example.com:80 check resolve-opts allow-dup-ip + server s2 myapp.example.com:81 check resolve-opts allow-dup-ip + + With the option allow-dup-ip set: + * if the nameserver returns a single IP address, then both servers will use + it + * If the nameserver returns 2 IP addresses, then each server will pick up a + different address + + Default value: not set + +resolve-prefer <family> + When DNS resolution is enabled for a server and multiple IP addresses from + different families are returned, HAProxy will prefer using an IP address + from the family mentioned in the "resolve-prefer" parameter. + Available families: "ipv4" and "ipv6" + + Default value: ipv6 + + Example: + + server s1 app1.domain.com:80 resolvers mydns resolve-prefer ipv6 + +resolve-net <network>[,<network[,...]] + This option prioritizes the choice of an ip address matching a network. This is + useful with clouds to prefer a local ip. In some cases, a cloud high + availability service can be announced with many ip addresses on many + different datacenters. The latency between datacenter is not negligible, so + this patch permits to prefer a local datacenter. If no address matches the + configured network, another address is selected. + + Example: + + server s1 app1.domain.com:80 resolvers mydns resolve-net 10.0.0.0/8 + +resolvers <id> + Points to an existing "resolvers" section to resolve current server's + hostname. + + Example: + + server s1 app1.domain.com:80 check resolvers mydns + + See also section 5.3 + +send-proxy + The "send-proxy" parameter enforces use of the PROXY protocol over any + connection established to this server. The PROXY protocol informs the other + end about the layer 3/4 addresses of the incoming connection, so that it can + know the client's address or the public address it accessed to, whatever the + upper layer protocol. For connections accepted by an "accept-proxy" or + "accept-netscaler-cip" listener, the advertised address will be used. Only + TCPv4 and TCPv6 address families are supported. Other families such as + Unix sockets, will report an UNKNOWN family. Servers using this option can + fully be chained to another instance of HAProxy listening with an + "accept-proxy" setting. This setting must not be used if the server isn't + aware of the protocol. When health checks are sent to the server, the PROXY + protocol is automatically used when this option is set, unless there is an + explicit "port" or "addr" directive, in which case an explicit + "check-send-proxy" directive would also be needed to use the PROXY protocol. + See also the "no-send-proxy" option of this section and "accept-proxy" and + "accept-netscaler-cip" option of the "bind" keyword. + +send-proxy-v2 + The "send-proxy-v2" parameter enforces use of the PROXY protocol version 2 + over any connection established to this server. The PROXY protocol informs + the other end about the layer 3/4 addresses of the incoming connection, so + that it can know the client's address or the public address it accessed to, + whatever the upper layer protocol. It also send ALPN information if an alpn + have been negotiated. This setting must not be used if the server isn't aware + of this version of the protocol. See also the "no-send-proxy-v2" option of + this section and send-proxy" option of the "bind" keyword. + +proxy-v2-options <option>[,<option>]* + The "proxy-v2-options" parameter add options to send in PROXY protocol + version 2 when "send-proxy-v2" is used. Options available are: + + - ssl : See also "send-proxy-v2-ssl". + - cert-cn : See also "send-proxy-v2-ssl-cn". + - ssl-cipher: Name of the used cipher. + - cert-sig : Signature algorithm of the used certificate. + - cert-key : Key algorithm of the used certificate + - authority : Host name value passed by the client (only SNI from a TLS + connection is supported). + - crc32c : Checksum of the PROXYv2 header. + - unique-id : Send a unique ID generated using the frontend's + "unique-id-format" within the PROXYv2 header. + This unique-id is primarily meant for "mode tcp". It can + lead to unexpected results in "mode http", because the + generated unique ID is also used for the first HTTP request + within a Keep-Alive connection. + +send-proxy-v2-ssl + The "send-proxy-v2-ssl" parameter enforces use of the PROXY protocol version + 2 over any connection established to this server. The PROXY protocol informs + the other end about the layer 3/4 addresses of the incoming connection, so + that it can know the client's address or the public address it accessed to, + whatever the upper layer protocol. In addition, the SSL information extension + of the PROXY protocol is added to the PROXY protocol header. This setting + must not be used if the server isn't aware of this version of the protocol. + See also the "no-send-proxy-v2-ssl" option of this section and the + "send-proxy-v2" option of the "bind" keyword. + +send-proxy-v2-ssl-cn + The "send-proxy-v2-ssl" parameter enforces use of the PROXY protocol version + 2 over any connection established to this server. The PROXY protocol informs + the other end about the layer 3/4 addresses of the incoming connection, so + that it can know the client's address or the public address it accessed to, + whatever the upper layer protocol. In addition, the SSL information extension + of the PROXY protocol, along along with the Common Name from the subject of + the client certificate (if any), is added to the PROXY protocol header. This + setting must not be used if the server isn't aware of this version of the + protocol. See also the "no-send-proxy-v2-ssl-cn" option of this section and + the "send-proxy-v2" option of the "bind" keyword. + +slowstart <start_time_in_ms> + The "slowstart" parameter for a server accepts a value in milliseconds which + indicates after how long a server which has just come back up will run at + full speed. Just as with every other time-based parameter, it can be entered + in any other explicit unit among { us, ms, s, m, h, d }. The speed grows + linearly from 0 to 100% during this time. The limitation applies to two + parameters : + + - maxconn: the number of connections accepted by the server will grow from 1 + to 100% of the usual dynamic limit defined by (minconn,maxconn,fullconn). + + - weight: when the backend uses a dynamic weighted algorithm, the weight + grows linearly from 1 to 100%. In this case, the weight is updated at every + health-check. For this reason, it is important that the "inter" parameter + is smaller than the "slowstart", in order to maximize the number of steps. + + The slowstart never applies when HAProxy starts, otherwise it would cause + trouble to running servers. It only applies when a server has been previously + seen as failed. + +sni <expression> + The "sni" parameter evaluates the sample fetch expression, converts it to a + string and uses the result as the host name sent in the SNI TLS extension to + the server. A typical use case is to send the SNI received from the client in + a bridged TCP/SSL scenario, using the "ssl_fc_sni" sample fetch for the + expression. THIS MUST NOT BE USED FOR HTTPS, where req.hdr(host) should be + used instead, since SNI in HTTPS must always match the Host field and clients + are allowed to use different host names over the same connection). If + "verify required" is set (which is the recommended setting), the resulting + name will also be matched against the server certificate's names. See the + "verify" directive for more details. If you want to set a SNI for health + checks, see the "check-sni" directive for more details. + +source <addr>[:<pl>[-<ph>]] [usesrc { <addr2>[:<port2>] | client | clientip } ] +source <addr>[:<port>] [usesrc { <addr2>[:<port2>] | hdr_ip(<hdr>[,<occ>]) } ] +source <addr>[:<pl>[-<ph>]] [interface <name>] ... + The "source" parameter sets the source address which will be used when + connecting to the server. It follows the exact same parameters and principle + as the backend "source" keyword, except that it only applies to the server + referencing it. Please consult the "source" keyword for details. + + Additionally, the "source" statement on a server line allows one to specify a + source port range by indicating the lower and higher bounds delimited by a + dash ('-'). Some operating systems might require a valid IP address when a + source port range is specified. It is permitted to have the same IP/range for + several servers. Doing so makes it possible to bypass the maximum of 64k + total concurrent connections. The limit will then reach 64k connections per + server. + + Since Linux 4.2/libc 2.23 IP_BIND_ADDRESS_NO_PORT is set for connections + specifying the source address without port(s). + +ssl + This option enables SSL ciphering on outgoing connections to the server. It + is critical to verify server certificates using "verify" when using SSL to + connect to servers, otherwise the communication is prone to trivial man in + the-middle attacks rendering SSL useless. When this option is used, health + checks are automatically sent in SSL too unless there is a "port" or an + "addr" directive indicating the check should be sent to a different location. + See the "no-ssl" to disable "ssl" option and "check-ssl" option to force + SSL health checks. + +ssl-max-ver [ SSLv3 | TLSv1.0 | TLSv1.1 | TLSv1.2 | TLSv1.3 ] + This option enforces use of <version> or lower when SSL is used to communicate + with the server. This option is also available on global statement + "ssl-default-server-options". See also "ssl-min-ver". + +ssl-min-ver [ SSLv3 | TLSv1.0 | TLSv1.1 | TLSv1.2 | TLSv1.3 ] + This option enforces use of <version> or upper when SSL is used to communicate + with the server. This option is also available on global statement + "ssl-default-server-options". See also "ssl-max-ver". + +ssl-reuse + This option may be used as "server" setting to reset any "no-ssl-reuse" + setting which would have been inherited from "default-server" directive as + default value. + It may also be used as "default-server" setting to reset any previous + "default-server" "no-ssl-reuse" setting. + +stick + This option may be used as "server" setting to reset any "non-stick" + setting which would have been inherited from "default-server" directive as + default value. + It may also be used as "default-server" setting to reset any previous + "default-server" "non-stick" setting. + +socks4 <addr>:<port> + This option enables upstream socks4 tunnel for outgoing connections to the + server. Using this option won't force the health check to go via socks4 by + default. You will have to use the keyword "check-via-socks4" to enable it. + +tcp-ut <delay> + Sets the TCP User Timeout for all outgoing connections to this server. This + option is available on Linux since version 2.6.37. It allows HAProxy to + configure a timeout for sockets which contain data not receiving an + acknowledgment for the configured delay. This is especially useful on + long-lived connections experiencing long idle periods such as remote + terminals or database connection pools, where the client and server timeouts + must remain high to allow a long period of idle, but where it is important to + detect that the server has disappeared in order to release all resources + associated with its connection (and the client's session). One typical use + case is also to force dead server connections to die when health checks are + too slow or during a soft reload since health checks are then disabled. The + argument is a delay expressed in milliseconds by default. This only works for + regular TCP connections, and is ignored for other protocols. + +tfo + This option enables using TCP fast open when connecting to servers, on + systems that support it (currently only the Linux kernel >= 4.11). + See the "tfo" bind option for more information about TCP fast open. + Please note that when using tfo, you should also use the "conn-failure", + "empty-response" and "response-timeout" keywords for "retry-on", or HAProxy + won't be able to retry the connection on failure. See also "no-tfo". + +track [<proxy>/]<server> + This option enables ability to set the current state of the server by tracking + another one. It is possible to track a server which itself tracks another + server, provided that at the end of the chain, a server has health checks + enabled. If <proxy> is omitted the current one is used. If disable-on-404 is + used, it has to be enabled on both proxies. + +tls-tickets + This option may be used as "server" setting to reset any "no-tls-tickets" + setting which would have been inherited from "default-server" directive as + default value. + The TLS ticket mechanism is only used up to TLS 1.2. + Forward Secrecy is compromised with TLS tickets, unless ticket keys + are periodically rotated (via reload or by using "tls-ticket-keys"). + It may also be used as "default-server" setting to reset any previous + "default-server" "no-tls-tickets" setting. + +verify [none|required] + This setting is only available when support for OpenSSL was built in. If set + to 'none', server certificate is not verified. In the other case, The + certificate provided by the server is verified using CAs from 'ca-file' and + optional CRLs from 'crl-file' after having checked that the names provided in + the certificate's subject and subjectAlternateNames attributes match either + the name passed using the "sni" directive, or if not provided, the static + host name passed using the "verifyhost" directive. When no name is found, the + certificate's names are ignored. For this reason, without SNI it's important + to use "verifyhost". On verification failure the handshake is aborted. It is + critically important to verify server certificates when using SSL to connect + to servers, otherwise the communication is prone to trivial man-in-the-middle + attacks rendering SSL totally useless. Unless "ssl_server_verify" appears in + the global section, "verify" is set to "required" by default. + +verifyhost <hostname> + This setting is only available when support for OpenSSL was built in, and + only takes effect if 'verify required' is also specified. This directive sets + a default static hostname to check the server's certificate against when no + SNI was used to connect to the server. If SNI is not used, this is the only + way to enable hostname verification. This static hostname, when set, will + also be used for health checks (which cannot provide an SNI value). If none + of the hostnames in the certificate match the specified hostname, the + handshake is aborted. The hostnames in the server-provided certificate may + include wildcards. See also "verify", "sni" and "no-verifyhost" options. + +weight <weight> + The "weight" parameter is used to adjust the server's weight relative to + other servers. All servers will receive a load proportional to their weight + relative to the sum of all weights, so the higher the weight, the higher the + load. The default weight is 1, and the maximal value is 256. A value of 0 + means the server will not participate in load-balancing but will still accept + persistent connections. If this parameter is used to distribute the load + according to server's capacity, it is recommended to start with values which + can both grow and shrink, for instance between 10 and 100 to leave enough + room above and below for later adjustments. + +ws { auto | h1 | h2 } + This option allows to configure the protocol used when relaying websocket + streams. This is most notably useful when using an HTTP/2 backend without the + support for H2 websockets through the RFC8441. + + The default mode is "auto". This will reuse the same protocol as the main + one. The only difference is when using ALPN. In this case, it can try to + downgrade the ALPN to "http/1.1" only for websocket streams if the configured + server ALPN contains it. + + The value "h1" is used to force HTTP/1.1 for websockets streams, through ALPN + if SSL ALPN is activated for the server. Similarly, "h2" can be used to + force HTTP/2.0 websockets. Use this value with care : the server must support + RFC8441 or an error will be reported by haproxy when relaying websockets. + + Note that NPN is not taken into account as its usage has been deprecated in + favor of the ALPN extension. + + See also "alpn" and "proto". + + +5.3. Server IP address resolution using DNS +------------------------------------------- + +HAProxy allows using a host name on the server line to retrieve its IP address +using name servers. By default, HAProxy resolves the name when parsing the +configuration file, at startup and cache the result for the process's life. +This is not sufficient in some cases, such as in Amazon where a server's IP +can change after a reboot or an ELB Virtual IP can change based on current +workload. +This chapter describes how HAProxy can be configured to process server's name +resolution at run time. +Whether run time server name resolution has been enable or not, HAProxy will +carry on doing the first resolution when parsing the configuration. + + +5.3.1. Global overview +---------------------- + +As we've seen in introduction, name resolution in HAProxy occurs at two +different steps of the process life: + + 1. when starting up, HAProxy parses the server line definition and matches a + host name. It uses libc functions to get the host name resolved. This + resolution relies on /etc/resolv.conf file. + + 2. at run time, HAProxy performs periodically name resolutions for servers + requiring DNS resolutions. + +A few other events can trigger a name resolution at run time: + - when a server's health check ends up in a connection timeout: this may be + because the server has a new IP address. So we need to trigger a name + resolution to know this new IP. + +When using resolvers, the server name can either be a hostname, or a SRV label. +HAProxy considers anything that starts with an underscore as a SRV label. If a +SRV label is specified, then the corresponding SRV records will be retrieved +from the DNS server, and the provided hostnames will be used. The SRV label +will be checked periodically, and if any server are added or removed, HAProxy +will automatically do the same. + +A few things important to notice: + - all the name servers are queried in the meantime. HAProxy will process the + first valid response. + + - a resolution is considered as invalid (NX, timeout, refused), when all the + servers return an error. + + +5.3.2. The resolvers section +---------------------------- + +This section is dedicated to host information related to name resolution in +HAProxy. There can be as many as resolvers section as needed. Each section can +contain many name servers. + +At startup, HAProxy tries to generate a resolvers section named "default", if +no section was named this way in the configuration. This section is used by +default by the httpclient and uses the parse-resolv-conf keyword. If HAProxy +failed to generate automatically this section, no error or warning are emitted. + +When multiple name servers are configured in a resolvers section, then HAProxy +uses the first valid response. In case of invalid responses, only the last one +is treated. Purpose is to give the chance to a slow server to deliver a valid +answer after a fast faulty or outdated server. + +When each server returns a different error type, then only the last error is +used by HAProxy. The following processing is applied on this error: + + 1. HAProxy retries the same DNS query with a new query type. The A queries are + switch to AAAA or the opposite. SRV queries are not concerned here. Timeout + errors are also excluded. + + 2. When the fallback on the query type was done (or not applicable), HAProxy + retries the original DNS query, with the preferred query type. + + 3. HAProxy retries previous steps <resolve_retries> times. If no valid + response is received after that, it stops the DNS resolution and reports + the error. + +For example, with 2 name servers configured in a resolvers section, the +following scenarios are possible: + + - First response is valid and is applied directly, second response is + ignored + + - First response is invalid and second one is valid, then second response is + applied + + - First response is a NX domain and second one a truncated response, then + HAProxy retries the query with a new type + + - First response is a NX domain and second one is a timeout, then HAProxy + retries the query with a new type + + - Query timed out for both name servers, then HAProxy retries it with the + same query type + +As a DNS server may not answer all the IPs in one DNS request, HAProxy keeps +a cache of previous answers, an answer will be considered obsolete after +<hold obsolete> seconds without the IP returned. + + +resolvers <resolvers id> + Creates a new name server list labeled <resolvers id> + +A resolvers section accept the following parameters: + +accepted_payload_size <nb> + Defines the maximum payload size accepted by HAProxy and announced to all the + name servers configured in this resolvers section. + <nb> is in bytes. If not set, HAProxy announces 512. (minimal value defined + by RFC 6891) + + Note: the maximum allowed value is 65535. Recommended value for UDP is + 4096 and it is not recommended to exceed 8192 except if you are sure + that your system and network can handle this (over 65507 makes no sense + since is the maximum UDP payload size). If you are using only TCP + nameservers to handle huge DNS responses, you should put this value + to the max: 65535. + +nameserver <name> <address>[:port] [param*] + Used to configure a nameserver. <name> of the nameserver should ne unique. + By default the <address> is considered of type datagram. This means if an + IPv4 or IPv6 is configured without special address prefixes (paragraph 11.) + the UDP protocol will be used. If an stream protocol address prefix is used, + the nameserver will be considered as a stream server (TCP for instance) and + "server" parameters found in 5.2 paragraph which are relevant for DNS + resolving will be considered. Note: currently, in TCP mode, 4 queries are + pipelined on the same connections. A batch of idle connections are removed + every 5 seconds. "maxconn" can be configured to limit the amount of those + concurrent connections and TLS should also usable if the server supports. + +parse-resolv-conf + Adds all nameservers found in /etc/resolv.conf to this resolvers nameservers + list. Ordered as if each nameserver in /etc/resolv.conf was individually + placed in the resolvers section in place of this directive. + +hold <status> <period> + Upon receiving the DNS response <status>, determines whether a server's state + should change from UP to DOWN. To make that determination, it checks whether + any valid status has been received during the past <period> in order to + counteract the just received invalid status. + + <status> : last name resolution status. + nx After receiving an NXDOMAIN status, check for any valid + status during the concluding period. + + refused After receiving a REFUSED status, check for any valid + status during the concluding period. + + timeout After the "timeout retry" has struck, check for any + valid status during the concluding period. + + other After receiving any other invalid status, check for any + valid status during the concluding period. + + valid Applies only to "http-request do-resolve" and + "tcp-request content do-resolve" actions. It defines the + period for which the server will maintain a valid response + before triggering another resolution. It does not affect + dynamic resolution of servers. + + obsolete Defines how long to wait before removing obsolete DNS + records after an updated answer record is received. It + applies to SRV records. + + <period> : Amount of time into the past during which a valid response must + have been received. It follows the HAProxy time format and is in + milliseconds by default. + + For a server that relies on dynamic DNS resolution to determine its IP + address, receiving an invalid DNS response, such as NXDOMAIN, will lead to + changing the server's state from UP to DOWN. The hold directives define how + far into the past to look for a valid response. If a valid response has been + received within <period>, the just received invalid status will be ignored. + + Unless a valid response has been receiving during the concluding period, the + server will be marked as DOWN. For example, if "hold nx 30s" is set and the + last received DNS response was NXDOMAIN, the server will be marked DOWN + unless a valid response has been received during the last 30 seconds. + + A server in the DOWN state will be marked UP immediately upon receiving a + valid status from the DNS server. + + A separate behavior exists for "hold valid" and "hold obsolete". + +resolve_retries <nb> + Defines the number <nb> of queries to send to resolve a server name before + giving up. + Default value: 3 + + A retry occurs on name server timeout or when the full sequence of DNS query + type failover is over and we need to start up from the default ANY query + type. + +timeout <event> <time> + Defines timeouts related to name resolution + <event> : the event on which the <time> timeout period applies to. + events available are: + - resolve : default time to trigger name resolutions when no + other time applied. + Default value: 1s + - retry : time between two DNS queries, when no valid response + have been received. + Default value: 1s + <time> : time related to the event. It follows the HAProxy time format. + <time> is expressed in milliseconds. + + Example: + + resolvers mydns + nameserver dns1 10.0.0.1:53 + nameserver dns2 10.0.0.2:53 + nameserver dns3 tcp@10.0.0.3:53 + parse-resolv-conf + resolve_retries 3 + timeout resolve 1s + timeout retry 1s + hold other 30s + hold refused 30s + hold nx 30s + hold timeout 30s + hold valid 10s + hold obsolete 30s + + +6. Cache +--------- + +HAProxy provides a cache, which was designed to perform cache on small objects +(favicon, css...). This is a minimalist low-maintenance cache which runs in +RAM. + +The cache is based on a memory area shared between all threads, and split in 1kB +blocks. + +If an object is not used anymore, it can be deleted to store a new object +independently of its expiration date. The oldest objects are deleted first +when we try to allocate a new one. + +The cache uses a hash of the host header and the URI as the key. + +It's possible to view the status of a cache using the Unix socket command +"show cache" consult section 9.3 "Unix Socket commands" of Management Guide +for more details. + +When an object is delivered from the cache, the server name in the log is +replaced by "<CACHE>". + + +6.1. Limitation +---------------- + +The cache won't store and won't deliver objects in these cases: + +- If the response is not a 200 +- If the response contains a Vary header and either the process-vary option is + disabled, or a currently unmanaged header is specified in the Vary value (only + accept-encoding and referer are managed for now) +- If the Content-Length + the headers size is greater than "max-object-size" +- If the response is not cacheable +- If the response does not have an explicit expiration time (s-maxage or max-age + Cache-Control directives or Expires header) or a validator (ETag or Last-Modified + headers) +- If the process-vary option is enabled and there are already max-secondary-entries + entries with the same primary key as the current response +- If the process-vary option is enabled and the response has an unknown encoding (not + mentioned in https://www.iana.org/assignments/http-parameters/http-parameters.xhtml) + while varying on the accept-encoding client header + +- If the request is not a GET +- If the HTTP version of the request is smaller than 1.1 +- If the request contains an Authorization header + + +6.2. Setup +----------- + +To setup a cache, you must define a cache section and use it in a proxy with +the corresponding http-request and response actions. + + +6.2.1. Cache section +--------------------- + +cache <name> + Declare a cache section, allocate a shared cache memory named <name>, the + size of cache is mandatory. + +total-max-size <megabytes> + Define the size in RAM of the cache in megabytes. This size is split in + blocks of 1kB which are used by the cache entries. Its maximum value is 4095. + +max-object-size <bytes> + Define the maximum size of the objects to be cached. Must not be greater than + an half of "total-max-size". If not set, it equals to a 256th of the cache size. + All objects with sizes larger than "max-object-size" will not be cached. + +max-age <seconds> + Define the maximum expiration duration. The expiration is set as the lowest + value between the s-maxage or max-age (in this order) directive in the + Cache-Control response header and this value. The default value is 60 + seconds, which means that you can't cache an object more than 60 seconds by + default. + +process-vary <on/off> + Enable or disable the processing of the Vary header. When disabled, a response + containing such a header will never be cached. When enabled, we need to calculate + a preliminary hash for a subset of request headers on all the incoming requests + (which might come with a cpu cost) which will be used to build a secondary key + for a given request (see RFC 7234#4.1). The default value is off (disabled). + +max-secondary-entries <number> + Define the maximum number of simultaneous secondary entries with the same primary + key in the cache. This needs the vary support to be enabled. Its default value is 10 + and should be passed a strictly positive integer. + + +6.2.2. Proxy section +--------------------- + +http-request cache-use <name> [ { if | unless } <condition> ] + Try to deliver a cached object from the cache <name>. This directive is also + mandatory to store the cache as it calculates the cache hash. If you want to + use a condition for both storage and delivering that's a good idea to put it + after this one. + +http-response cache-store <name> [ { if | unless } <condition> ] + Store an http-response within the cache. The storage of the response headers + is done at this step, which means you can use others http-response actions + to modify headers before or after the storage of the response. This action + is responsible for the setup of the cache storage filter. + + +Example: + + backend bck1 + mode http + + http-request cache-use foobar + http-response cache-store foobar + server srv1 127.0.0.1:80 + + cache foobar + total-max-size 4 + max-age 240 + + +7. Using ACLs and fetching samples +---------------------------------- + +HAProxy is capable of extracting data from request or response streams, from +client or server information, from tables, environmental information etc... +The action of extracting such data is called fetching a sample. Once retrieved, +these samples may be used for various purposes such as a key to a stick-table, +but most common usages consist in matching them against predefined constant +data called patterns. + + +7.1. ACL basics +--------------- + +The use of Access Control Lists (ACL) provides a flexible solution to perform +content switching and generally to take decisions based on content extracted +from the request, the response or any environmental status. The principle is +simple : + + - extract a data sample from a stream, table or the environment + - optionally apply some format conversion to the extracted sample + - apply one or multiple pattern matching methods on this sample + - perform actions only when a pattern matches the sample + +The actions generally consist in blocking a request, selecting a backend, or +adding a header. + +In order to define a test, the "acl" keyword is used. The syntax is : + + acl <aclname> <criterion> [flags] [operator] [<value>] ... + +This creates a new ACL <aclname> or completes an existing one with new tests. +Those tests apply to the portion of request/response specified in <criterion> +and may be adjusted with optional flags [flags]. Some criteria also support +an operator which may be specified before the set of values. Optionally some +conversion operators may be applied to the sample, and they will be specified +as a comma-delimited list of keywords just after the first keyword. The values +are of the type supported by the criterion, and are separated by spaces. + +ACL names must be formed from upper and lower case letters, digits, '-' (dash), +'_' (underscore) , '.' (dot) and ':' (colon). ACL names are case-sensitive, +which means that "my_acl" and "My_Acl" are two different ACLs. + +There is no enforced limit to the number of ACLs. The unused ones do not affect +performance, they just consume a small amount of memory. + +The criterion generally is the name of a sample fetch method, or one of its ACL +specific declinations. The default test method is implied by the output type of +this sample fetch method. The ACL declinations can describe alternate matching +methods of a same sample fetch method. The sample fetch methods are the only +ones supporting a conversion. + +Sample fetch methods return data which can be of the following types : + - boolean + - integer (signed or unsigned) + - IPv4 or IPv6 address + - string + - data block + +Converters transform any of these data into any of these. For example, some +converters might convert a string to a lower-case string while other ones +would turn a string to an IPv4 address, or apply a netmask to an IP address. +The resulting sample is of the type of the last converter applied to the list, +which defaults to the type of the sample fetch method. + +Each sample or converter returns data of a specific type, specified with its +keyword in this documentation. When an ACL is declared using a standard sample +fetch method, certain types automatically involved a default matching method +which are summarized in the table below : + + +---------------------+-----------------+ + | Sample or converter | Default | + | output type | matching method | + +---------------------+-----------------+ + | boolean | bool | + +---------------------+-----------------+ + | integer | int | + +---------------------+-----------------+ + | ip | ip | + +---------------------+-----------------+ + | string | str | + +---------------------+-----------------+ + | binary | none, use "-m" | + +---------------------+-----------------+ + +Note that in order to match a binary samples, it is mandatory to specify a +matching method, see below. + +The ACL engine can match these types against patterns of the following types : + - boolean + - integer or integer range + - IP address / network + - string (exact, substring, suffix, prefix, subdir, domain) + - regular expression + - hex block + +The following ACL flags are currently supported : + + -i : ignore case during matching of all subsequent patterns. + -f : load patterns from a file. + -m : use a specific pattern matching method + -n : forbid the DNS resolutions + -M : load the file pointed by -f like a map file. + -u : force the unique id of the ACL + -- : force end of flags. Useful when a string looks like one of the flags. + +The "-f" flag is followed by the name of a file from which all lines will be +read as individual values. It is even possible to pass multiple "-f" arguments +if the patterns are to be loaded from multiple files. Empty lines as well as +lines beginning with a sharp ('#') will be ignored. All leading spaces and tabs +will be stripped. If it is absolutely necessary to insert a valid pattern +beginning with a sharp, just prefix it with a space so that it is not taken for +a comment. Depending on the data type and match method, HAProxy may load the +lines into a binary tree, allowing very fast lookups. This is true for IPv4 and +exact string matching. In this case, duplicates will automatically be removed. + +The "-M" flag allows an ACL to use a map file. If this flag is set, the file is +parsed as two column file. The first column contains the patterns used by the +ACL, and the second column contain the samples. The sample can be used later by +a map. This can be useful in some rare cases where an ACL would just be used to +check for the existence of a pattern in a map before a mapping is applied. + +The "-u" flag forces the unique id of the ACL. This unique id is used with the +socket interface to identify ACL and dynamically change its values. Note that a +file is always identified by its name even if an id is set. + +Also, note that the "-i" flag applies to subsequent entries and not to entries +loaded from files preceding it. For instance : + + acl valid-ua hdr(user-agent) -f exact-ua.lst -i -f generic-ua.lst test + +In this example, each line of "exact-ua.lst" will be exactly matched against +the "user-agent" header of the request. Then each line of "generic-ua" will be +case-insensitively matched. Then the word "test" will be insensitively matched +as well. + +The "-m" flag is used to select a specific pattern matching method on the input +sample. All ACL-specific criteria imply a pattern matching method and generally +do not need this flag. However, this flag is useful with generic sample fetch +methods to describe how they're going to be matched against the patterns. This +is required for sample fetches which return data type for which there is no +obvious matching method (e.g. string or binary). When "-m" is specified and +followed by a pattern matching method name, this method is used instead of the +default one for the criterion. This makes it possible to match contents in ways +that were not initially planned, or with sample fetch methods which return a +string. The matching method also affects the way the patterns are parsed. + +The "-n" flag forbids the dns resolutions. It is used with the load of ip files. +By default, if the parser cannot parse ip address it considers that the parsed +string is maybe a domain name and try dns resolution. The flag "-n" disable this +resolution. It is useful for detecting malformed ip lists. Note that if the DNS +server is not reachable, the HAProxy configuration parsing may last many minutes +waiting for the timeout. During this time no error messages are displayed. The +flag "-n" disable this behavior. Note also that during the runtime, this +function is disabled for the dynamic acl modifications. + +There are some restrictions however. Not all methods can be used with all +sample fetch methods. Also, if "-m" is used in conjunction with "-f", it must +be placed first. The pattern matching method must be one of the following : + + - "found" : only check if the requested sample could be found in the stream, + but do not compare it against any pattern. It is recommended not + to pass any pattern to avoid confusion. This matching method is + particularly useful to detect presence of certain contents such + as headers, cookies, etc... even if they are empty and without + comparing them to anything nor counting them. + + - "bool" : check the value as a boolean. It can only be applied to fetches + which return a boolean or integer value, and takes no pattern. + Value zero or false does not match, all other values do match. + + - "int" : match the value as an integer. It can be used with integer and + boolean samples. Boolean false is integer 0, true is integer 1. + + - "ip" : match the value as an IPv4 or IPv6 address. It is compatible + with IP address samples only, so it is implied and never needed. + + - "bin" : match the contents against a hexadecimal string representing a + binary sequence. This may be used with binary or string samples. + + - "len" : match the sample's length as an integer. This may be used with + binary or string samples. + + - "str" : exact match : match the contents against a string. This may be + used with binary or string samples. + + - "sub" : substring match : check that the contents contain at least one of + the provided string patterns. This may be used with binary or + string samples. + + - "reg" : regex match : match the contents against a list of regular + expressions. This may be used with binary or string samples. + + - "beg" : prefix match : check that the contents begin like the provided + string patterns. This may be used with binary or string samples. + + - "end" : suffix match : check that the contents end like the provided + string patterns. This may be used with binary or string samples. + + - "dir" : subdir match : check that a slash-delimited portion of the + contents exactly matches one of the provided string patterns. + This may be used with binary or string samples. + + - "dom" : domain match : check that a dot-delimited portion of the contents + exactly match one of the provided string patterns. This may be + used with binary or string samples. + +For example, to quickly detect the presence of cookie "JSESSIONID" in an HTTP +request, it is possible to do : + + acl jsess_present req.cook(JSESSIONID) -m found + +In order to apply a regular expression on the 500 first bytes of data in the +buffer, one would use the following acl : + + acl script_tag req.payload(0,500) -m reg -i <script> + +On systems where the regex library is much slower when using "-i", it is +possible to convert the sample to lowercase before matching, like this : + + acl script_tag req.payload(0,500),lower -m reg <script> + +All ACL-specific criteria imply a default matching method. Most often, these +criteria are composed by concatenating the name of the original sample fetch +method and the matching method. For example, "hdr_beg" applies the "beg" match +to samples retrieved using the "hdr" fetch method. This matching method is only +usable when the keyword is used alone, without any converter. In case any such +converter were to be applied after such an ACL keyword, the default matching +method from the ACL keyword is simply ignored since what will matter for the +matching is the output type of the last converter. Since all ACL-specific +criteria rely on a sample fetch method, it is always possible instead to use +the original sample fetch method and the explicit matching method using "-m". + +If an alternate match is specified using "-m" on an ACL-specific criterion, +the matching method is simply applied to the underlying sample fetch method. +For example, all ACLs below are exact equivalent : + + acl short_form hdr_beg(host) www. + acl alternate1 hdr_beg(host) -m beg www. + acl alternate2 hdr_dom(host) -m beg www. + acl alternate3 hdr(host) -m beg www. + + +The table below summarizes the compatibility matrix between sample or converter +types and the pattern types to fetch against. It indicates for each compatible +combination the name of the matching method to be used, surrounded with angle +brackets ">" and "<" when the method is the default one and will work by +default without "-m". + + +-------------------------------------------------+ + | Input sample type | + +----------------------+---------+---------+---------+---------+---------+ + | pattern type | boolean | integer | ip | string | binary | + +----------------------+---------+---------+---------+---------+---------+ + | none (presence only) | found | found | found | found | found | + +----------------------+---------+---------+---------+---------+---------+ + | none (boolean value) |> bool <| bool | | bool | | + +----------------------+---------+---------+---------+---------+---------+ + | integer (value) | int |> int <| int | int | | + +----------------------+---------+---------+---------+---------+---------+ + | integer (length) | len | len | len | len | len | + +----------------------+---------+---------+---------+---------+---------+ + | IP address | | |> ip <| ip | ip | + +----------------------+---------+---------+---------+---------+---------+ + | exact string | str | str | str |> str <| str | + +----------------------+---------+---------+---------+---------+---------+ + | prefix | beg | beg | beg | beg | beg | + +----------------------+---------+---------+---------+---------+---------+ + | suffix | end | end | end | end | end | + +----------------------+---------+---------+---------+---------+---------+ + | substring | sub | sub | sub | sub | sub | + +----------------------+---------+---------+---------+---------+---------+ + | subdir | dir | dir | dir | dir | dir | + +----------------------+---------+---------+---------+---------+---------+ + | domain | dom | dom | dom | dom | dom | + +----------------------+---------+---------+---------+---------+---------+ + | regex | reg | reg | reg | reg | reg | + +----------------------+---------+---------+---------+---------+---------+ + | hex block | | | | bin | bin | + +----------------------+---------+---------+---------+---------+---------+ + + +7.1.1. Matching booleans +------------------------ + +In order to match a boolean, no value is needed and all values are ignored. +Boolean matching is used by default for all fetch methods of type "boolean". +When boolean matching is used, the fetched value is returned as-is, which means +that a boolean "true" will always match and a boolean "false" will never match. + +Boolean matching may also be enforced using "-m bool" on fetch methods which +return an integer value. Then, integer value 0 is converted to the boolean +"false" and all other values are converted to "true". + + +7.1.2. Matching integers +------------------------ + +Integer matching applies by default to integer fetch methods. It can also be +enforced on boolean fetches using "-m int". In this case, "false" is converted +to the integer 0, and "true" is converted to the integer 1. + +Integer matching also supports integer ranges and operators. Note that integer +matching only applies to positive values. A range is a value expressed with a +lower and an upper bound separated with a colon, both of which may be omitted. + +For instance, "1024:65535" is a valid range to represent a range of +unprivileged ports, and "1024:" would also work. "0:1023" is a valid +representation of privileged ports, and ":1023" would also work. + +As a special case, some ACL functions support decimal numbers which are in fact +two integers separated by a dot. This is used with some version checks for +instance. All integer properties apply to those decimal numbers, including +ranges and operators. + +For an easier usage, comparison operators are also supported. Note that using +operators with ranges does not make much sense and is strongly discouraged. +Similarly, it does not make much sense to perform order comparisons with a set +of values. + +Available operators for integer matching are : + + eq : true if the tested value equals at least one value + ge : true if the tested value is greater than or equal to at least one value + gt : true if the tested value is greater than at least one value + le : true if the tested value is less than or equal to at least one value + lt : true if the tested value is less than at least one value + +For instance, the following ACL matches any negative Content-Length header : + + acl negative-length req.hdr_val(content-length) lt 0 + +This one matches SSL versions between 3.0 and 3.1 (inclusive) : + + acl sslv3 req.ssl_ver 3:3.1 + + +7.1.3. Matching strings +----------------------- + +String matching applies to string or binary fetch methods, and exists in 6 +different forms : + + - exact match (-m str) : the extracted string must exactly match the + patterns; + + - substring match (-m sub) : the patterns are looked up inside the + extracted string, and the ACL matches if any of them is found inside; + + - prefix match (-m beg) : the patterns are compared with the beginning of + the extracted string, and the ACL matches if any of them matches. + + - suffix match (-m end) : the patterns are compared with the end of the + extracted string, and the ACL matches if any of them matches. + + - subdir match (-m dir) : the patterns are looked up anywhere inside the + extracted string, delimited with slashes ("/"), the beginning or the end + of the string. The ACL matches if any of them matches. As such, the string + "/images/png/logo/32x32.png", would match "/images", "/images/png", + "images/png", "/png/logo", "logo/32x32.png" or "32x32.png" but not "png" + nor "32x32". + + - domain match (-m dom) : the patterns are looked up anywhere inside the + extracted string, delimited with dots ("."), colons (":"), slashes ("/"), + question marks ("?"), the beginning or the end of the string. This is made + to be used with URLs. Leading and trailing delimiters in the pattern are + ignored. The ACL matches if any of them matches. As such, in the example + string "http://www1.dc-eu.example.com:80/blah", the patterns "http", + "www1", ".www1", "dc-eu", "example", "com", "80", "dc-eu.example", + "blah", ":www1:", "dc-eu.example:80" would match, but not "eu" nor "dc". + Using it to match domain suffixes for filtering or routing is generally + not a good idea, as the routing could easily be fooled by prepending the + matching prefix in front of another domain for example. + +String matching applies to verbatim strings as they are passed, with the +exception of the backslash ("\") which makes it possible to escape some +characters such as the space. If the "-i" flag is passed before the first +string, then the matching will be performed ignoring the case. In order +to match the string "-i", either set it second, or pass the "--" flag +before the first string. Same applies of course to match the string "--". + +Do not use string matches for binary fetches which might contain null bytes +(0x00), as the comparison stops at the occurrence of the first null byte. +Instead, convert the binary fetch to a hex string with the hex converter first. + +Example: + # matches if the string <tag> is present in the binary sample + acl tag_found req.payload(0,0),hex -m sub 3C7461673E + + +7.1.4. Matching regular expressions (regexes) +--------------------------------------------- + +Just like with string matching, regex matching applies to verbatim strings as +they are passed, with the exception of the backslash ("\") which makes it +possible to escape some characters such as the space. If the "-i" flag is +passed before the first regex, then the matching will be performed ignoring +the case. In order to match the string "-i", either set it second, or pass +the "--" flag before the first string. Same principle applies of course to +match the string "--". + + +7.1.5. Matching arbitrary data blocks +------------------------------------- + +It is possible to match some extracted samples against a binary block which may +not safely be represented as a string. For this, the patterns must be passed as +a series of hexadecimal digits in an even number, when the match method is set +to binary. Each sequence of two digits will represent a byte. The hexadecimal +digits may be used upper or lower case. + +Example : + # match "Hello\n" in the input stream (\x48 \x65 \x6c \x6c \x6f \x0a) + acl hello req.payload(0,6) -m bin 48656c6c6f0a + + +7.1.6. Matching IPv4 and IPv6 addresses +--------------------------------------- + +IPv4 addresses values can be specified either as plain addresses or with a +netmask appended, in which case the IPv4 address matches whenever it is +within the network. Plain addresses may also be replaced with a resolvable +host name, but this practice is generally discouraged as it makes it more +difficult to read and debug configurations. If hostnames are used, you should +at least ensure that they are present in /etc/hosts so that the configuration +does not depend on any random DNS match at the moment the configuration is +parsed. + +The dotted IPv4 address notation is supported in both regular as well as the +abbreviated form with all-0-octets omitted: + + +------------------+------------------+------------------+ + | Example 1 | Example 2 | Example 3 | + +------------------+------------------+------------------+ + | 192.168.0.1 | 10.0.0.12 | 127.0.0.1 | + | 192.168.1 | 10.12 | 127.1 | + | 192.168.0.1/22 | 10.0.0.12/8 | 127.0.0.1/8 | + | 192.168.1/22 | 10.12/8 | 127.1/8 | + +------------------+------------------+------------------+ + +Notice that this is different from RFC 4632 CIDR address notation in which +192.168.42/24 would be equivalent to 192.168.42.0/24. + +IPv6 may be entered in their usual form, with or without a netmask appended. +Only bit counts are accepted for IPv6 netmasks. In order to avoid any risk of +trouble with randomly resolved IP addresses, host names are never allowed in +IPv6 patterns. + +HAProxy is also able to match IPv4 addresses with IPv6 addresses in the +following situations : + - tested address is IPv4, pattern address is IPv4, the match applies + in IPv4 using the supplied mask if any. + - tested address is IPv6, pattern address is IPv6, the match applies + in IPv6 using the supplied mask if any. + - tested address is IPv6, pattern address is IPv4, the match applies in IPv4 + using the pattern's mask if the IPv6 address matches with 2002:IPV4::, + ::IPV4 or ::ffff:IPV4, otherwise it fails. + - tested address is IPv4, pattern address is IPv6, the IPv4 address is first + converted to IPv6 by prefixing ::ffff: in front of it, then the match is + applied in IPv6 using the supplied IPv6 mask. + + +7.2. Using ACLs to form conditions +---------------------------------- + +Some actions are only performed upon a valid condition. A condition is a +combination of ACLs with operators. 3 operators are supported : + + - AND (implicit) + - OR (explicit with the "or" keyword or the "||" operator) + - Negation with the exclamation mark ("!") + +A condition is formed as a disjunctive form: + + [!]acl1 [!]acl2 ... [!]acln { or [!]acl1 [!]acl2 ... [!]acln } ... + +Such conditions are generally used after an "if" or "unless" statement, +indicating when the condition will trigger the action. + +For instance, to block HTTP requests to the "*" URL with methods other than +"OPTIONS", as well as POST requests without content-length, and GET or HEAD +requests with a content-length greater than 0, and finally every request which +is not either GET/HEAD/POST/OPTIONS ! + + acl missing_cl req.hdr_cnt(Content-length) eq 0 + http-request deny if HTTP_URL_STAR !METH_OPTIONS || METH_POST missing_cl + http-request deny if METH_GET HTTP_CONTENT + http-request deny unless METH_GET or METH_POST or METH_OPTIONS + +To select a different backend for requests to static contents on the "www" site +and to every request on the "img", "video", "download" and "ftp" hosts : + + acl url_static path_beg /static /images /img /css + acl url_static path_end .gif .png .jpg .css .js + acl host_www hdr_beg(host) -i www + acl host_static hdr_beg(host) -i img. video. download. ftp. + + # now use backend "static" for all static-only hosts, and for static URLs + # of host "www". Use backend "www" for the rest. + use_backend static if host_static or host_www url_static + use_backend www if host_www + +It is also possible to form rules using "anonymous ACLs". Those are unnamed ACL +expressions that are built on the fly without needing to be declared. They must +be enclosed between braces, with a space before and after each brace (because +the braces must be seen as independent words). Example : + + The following rule : + + acl missing_cl req.hdr_cnt(Content-length) eq 0 + http-request deny if METH_POST missing_cl + + Can also be written that way : + + http-request deny if METH_POST { req.hdr_cnt(Content-length) eq 0 } + +It is generally not recommended to use this construct because it's a lot easier +to leave errors in the configuration when written that way. However, for very +simple rules matching only one source IP address for instance, it can make more +sense to use them than to declare ACLs with random names. Another example of +good use is the following : + + With named ACLs : + + acl site_dead nbsrv(dynamic) lt 2 + acl site_dead nbsrv(static) lt 2 + monitor fail if site_dead + + With anonymous ACLs : + + monitor fail if { nbsrv(dynamic) lt 2 } || { nbsrv(static) lt 2 } + +See section 4.2 for detailed help on the "http-request deny" and "use_backend" +keywords. + + +7.3. Fetching samples +--------------------- + +Historically, sample fetch methods were only used to retrieve data to match +against patterns using ACLs. With the arrival of stick-tables, a new class of +sample fetch methods was created, most often sharing the same syntax as their +ACL counterpart. These sample fetch methods are also known as "fetches". As +of now, ACLs and fetches have converged. All ACL fetch methods have been made +available as fetch methods, and ACLs may use any sample fetch method as well. + +This section details all available sample fetch methods and their output type. +Some sample fetch methods have deprecated aliases that are used to maintain +compatibility with existing configurations. They are then explicitly marked as +deprecated and should not be used in new setups. + +The ACL derivatives are also indicated when available, with their respective +matching methods. These ones all have a well defined default pattern matching +method, so it is never necessary (though allowed) to pass the "-m" option to +indicate how the sample will be matched using ACLs. + +As indicated in the sample type versus matching compatibility matrix above, +when using a generic sample fetch method in an ACL, the "-m" option is +mandatory unless the sample type is one of boolean, integer, IPv4 or IPv6. When +the same keyword exists as an ACL keyword and as a standard fetch method, the +ACL engine will automatically pick the ACL-only one by default. + +Some of these keywords support one or multiple mandatory arguments, and one or +multiple optional arguments. These arguments are strongly typed and are checked +when the configuration is parsed so that there is no risk of running with an +incorrect argument (e.g. an unresolved backend name). Fetch function arguments +are passed between parenthesis and are delimited by commas. When an argument +is optional, it will be indicated below between square brackets ('[ ]'). When +all arguments are optional, the parenthesis may be omitted. + +Thus, the syntax of a standard sample fetch method is one of the following : + - name + - name(arg1) + - name(arg1,arg2) + + +7.3.1. Converters +----------------- + +Sample fetch methods may be combined with transformations to be applied on top +of the fetched sample (also called "converters"). These combinations form what +is called "sample expressions" and the result is a "sample". Initially this +was only supported by "stick on" and "stick store-request" directives but this +has now be extended to all places where samples may be used (ACLs, log-format, +unique-id-format, add-header, ...). + +These transformations are enumerated as a series of specific keywords after the +sample fetch method. These keywords may equally be appended immediately after +the fetch keyword's argument, delimited by a comma. These keywords can also +support some arguments (e.g. a netmask) which must be passed in parenthesis. + +A certain category of converters are bitwise and arithmetic operators which +support performing basic operations on integers. Some bitwise operations are +supported (and, or, xor, cpl) and some arithmetic operations are supported +(add, sub, mul, div, mod, neg). Some comparators are provided (odd, even, not, +bool) which make it possible to report a match without having to write an ACL. + +The currently available list of transformation keywords include : + +51d.single(<prop>[,<prop>*]) + Returns values for the properties requested as a string, where values are + separated by the delimiter specified with "51degrees-property-separator". + The device is identified using the User-Agent header passed to the + converter. The function can be passed up to five property names, and if a + property name can't be found, the value "NoData" is returned. + + Example : + # Here the header "X-51D-DeviceTypeMobileTablet" is added to the request, + # containing values for the three properties requested by using the + # User-Agent passed to the converter. + frontend http-in + bind *:8081 + default_backend servers + http-request set-header X-51D-DeviceTypeMobileTablet \ + %[req.fhdr(User-Agent),51d.single(DeviceType,IsMobile,IsTablet)] + +add(<value>) + Adds <value> to the input value of type signed integer, and returns the + result as a signed integer. <value> can be a numeric value or a variable + name. The name of the variable starts with an indication about its scope. The + scopes allowed are: + "proc" : the variable is shared with the whole process + "sess" : the variable is shared with the whole session + "txn" : the variable is shared with the transaction (request and response) + "req" : the variable is shared only during request processing + "res" : the variable is shared only during response processing + This prefix is followed by a name. The separator is a '.'. The name may only + contain characters 'a-z', 'A-Z', '0-9', '.' and '_'. + +add_item(<delim>,[<var>][,<suff>]]) + Concatenates a minimum of 2 and up to 3 fields after the current sample which + is then turned into a string. The first one, <delim>, is a constant string, + that will be appended immediately after the existing sample if an existing + sample is not empty and either the <var> or the <suff> is not empty. The + second one, <var>, is a variable name. The variable will be looked up, its + contents converted to a string, and it will be appended immediately after + the <delim> part. If the variable is not found, nothing is appended. It is + optional and may optionally be followed by a constant string <suff>, however + if <var> is omitted, then <suff> is mandatory. This converter is similar to + the concat converter and can be used to build new variables made of a + succession of other variables but the main difference is that it does the + checks if adding a delimiter makes sense as wouldn't be the case if e.g. the + current sample is empty. That situation would require 2 separate rules using + concat converter where the first rule would have to check if the current + sample string is empty before adding a delimiter. If commas or closing + parenthesis are needed as delimiters, they must be protected by quotes or + backslashes, themselves protected so that they are not stripped by the first + level parser (please see section 2.2 for quoting and escaping). See examples + below. + + Example: + http-request set-var(req.tagged) 'var(req.tagged),add_item(",",req.score1,"(site1)") if src,in_table(site1)' + http-request set-var(req.tagged) 'var(req.tagged),add_item(",",req.score2,"(site2)") if src,in_table(site2)' + http-request set-var(req.tagged) 'var(req.tagged),add_item(",",req.score3,"(site3)") if src,in_table(site3)' + http-request set-header x-tagged %[var(req.tagged)] + + http-request set-var(req.tagged) 'var(req.tagged),add_item(",",req.score1),add_item(",",req.score2)' + http-request set-var(req.tagged) 'var(req.tagged),add_item(",",,(site1))' if src,in_table(site1) + +aes_gcm_dec(<bits>,<nonce>,<key>,<aead_tag>) + Decrypts the raw byte input using the AES128-GCM, AES192-GCM or + AES256-GCM algorithm, depending on the <bits> parameter. All other parameters + need to be base64 encoded and the returned result is in raw byte format. + If the <aead_tag> validation fails, the converter doesn't return any data. + The <nonce>, <key> and <aead_tag> can either be strings or variables. This + converter requires at least OpenSSL 1.0.1. + + Example: + http-response set-header X-Decrypted-Text %[var(txn.enc),\ + aes_gcm_dec(128,txn.nonce,Zm9vb2Zvb29mb29wZm9vbw==,txn.aead_tag)] + +and(<value>) + Performs a bitwise "AND" between <value> and the input value of type signed + integer, and returns the result as an signed integer. <value> can be a + numeric value or a variable name. The name of the variable starts with an + indication about its scope. The scopes allowed are: + "proc" : the variable is shared with the whole process + "sess" : the variable is shared with the whole session + "txn" : the variable is shared with the transaction (request and response) + "req" : the variable is shared only during request processing + "res" : the variable is shared only during response processing + This prefix is followed by a name. The separator is a '.'. The name may only + contain characters 'a-z', 'A-Z', '0-9', '.' and '_'. + +b64dec + Converts (decodes) a base64 encoded input string to its binary + representation. It performs the inverse operation of base64(). + For base64url("URL and Filename Safe Alphabet" (RFC 4648)) variant + see "ub64dec". + +base64 + Converts a binary input sample to a base64 string. It is used to log or + transfer binary content in a way that can be reliably transferred (e.g. + an SSL ID can be copied in a header). For base64url("URL and Filename + Safe Alphabet" (RFC 4648)) variant see "ub64enc". + +be2dec(<separator>,<chunk_size>,[<truncate>]) + Converts big-endian binary input sample to a string containing an unsigned + integer number per <chunk_size> input bytes. <separator> is put every + <chunk_size> binary input bytes if specified. <truncate> flag indicates + whatever binary input is truncated at <chunk_size> boundaries. <chunk_size> + maximum value is limited by the size of long long int (8 bytes). + + Example: + bin(01020304050607),be2dec(:,2) # 258:772:1286:7 + bin(01020304050607),be2dec(-,2,1) # 258-772-1286 + bin(01020304050607),be2dec(,2,1) # 2587721286 + bin(7f000001),be2dec(.,1) # 127.0.0.1 + +be2hex([<separator>],[<chunk_size>],[<truncate>]) + Converts big-endian binary input sample to a hex string containing two hex + digits per input byte. It is used to log or transfer hex dumps of some + binary input data in a way that can be reliably transferred (e.g. an SSL ID + can be copied in a header). <separator> is put every <chunk_size> binary + input bytes if specified. <truncate> flag indicates whatever binary input is + truncated at <chunk_size> boundaries. + + Example: + bin(01020304050607),be2hex # 01020304050607 + bin(01020304050607),be2hex(:,2) # 0102:0304:0506:07 + bin(01020304050607),be2hex(--,2,1) # 0102--0304--0506 + bin(0102030405060708),be2hex(,3,1) # 010203040506 + +bool + Returns a boolean TRUE if the input value of type signed integer is + non-null, otherwise returns FALSE. Used in conjunction with and(), it can be + used to report true/false for bit testing on input values (e.g. verify the + presence of a flag). + +bytes(<offset>[,<length>]) + Extracts some bytes from an input binary sample. The result is a binary + sample starting at an offset (in bytes) of the original sample and + optionally truncated at the given length. + +concat([<start>],[<var>],[<end>]) + Concatenates up to 3 fields after the current sample which is then turned to + a string. The first one, <start>, is a constant string, that will be appended + immediately after the existing sample. It may be omitted if not used. The + second one, <var>, is a variable name. The variable will be looked up, its + contents converted to a string, and it will be appended immediately after the + <first> part. If the variable is not found, nothing is appended. It may be + omitted as well. The third field, <end> is a constant string that will be + appended after the variable. It may also be omitted. Together, these elements + allow to concatenate variables with delimiters to an existing set of + variables. This can be used to build new variables made of a succession of + other variables, such as colon-delimited values. If commas or closing + parenthesis are needed as delimiters, they must be protected by quotes or + backslashes, themselves protected so that they are not stripped by the first + level parser. This is often used to build composite variables from other + ones, but sometimes using a format string with multiple fields may be more + convenient. See examples below. + + Example: + tcp-request session set-var(sess.src) src + tcp-request session set-var(sess.dn) ssl_c_s_dn + tcp-request session set-var(txn.sig) str(),concat(<ip=,sess.ip,>),concat(<dn=,sess.dn,>) + tcp-request session set-var(txn.ipport) "str(),concat('addr=(',sess.ip),concat(',',sess.port,')')" + tcp-request session set-var-fmt(txn.ipport) "addr=(%[sess.ip],%[sess.port])" ## does the same + http-request set-header x-hap-sig %[var(txn.sig)] + +cpl + Takes the input value of type signed integer, applies a ones-complement + (flips all bits) and returns the result as an signed integer. + +crc32([<avalanche>]) + Hashes a binary input sample into an unsigned 32-bit quantity using the CRC32 + hash function. Optionally, it is possible to apply a full avalanche hash + function to the output if the optional <avalanche> argument equals 1. This + converter uses the same functions as used by the various hash-based load + balancing algorithms, so it will provide exactly the same results. It is + provided for compatibility with other software which want a CRC32 to be + computed on some input keys, so it follows the most common implementation as + found in Ethernet, Gzip, PNG, etc... It is slower than the other algorithms + but may provide a better or at least less predictable distribution. It must + not be used for security purposes as a 32-bit hash is trivial to break. See + also "djb2", "sdbm", "wt6", "crc32c" and the "hash-type" directive. + +crc32c([<avalanche>]) + Hashes a binary input sample into an unsigned 32-bit quantity using the CRC32C + hash function. Optionally, it is possible to apply a full avalanche hash + function to the output if the optional <avalanche> argument equals 1. This + converter uses the same functions as described in RFC4960, Appendix B [8]. + It is provided for compatibility with other software which want a CRC32C to be + computed on some input keys. It is slower than the other algorithms and it must + not be used for security purposes as a 32-bit hash is trivial to break. See + also "djb2", "sdbm", "wt6", "crc32" and the "hash-type" directive. + +cut_crlf + Cuts the string representation of the input sample on the first carriage + return ('\r') or newline ('\n') character found. Only the string length is + updated. + +da-csv-conv(<prop>[,<prop>*]) + Asks the DeviceAtlas converter to identify the User Agent string passed on + input, and to emit a string made of the concatenation of the properties + enumerated in argument, delimited by the separator defined by the global + keyword "deviceatlas-property-separator", or by default the pipe character + ('|'). There's a limit of 12 different properties imposed by the HAProxy + configuration language. + + Example: + frontend www + bind *:8881 + default_backend servers + http-request set-header X-DeviceAtlas-Data %[req.fhdr(User-Agent),da-csv(primaryHardwareType,osName,osVersion,browserName,browserVersion,browserRenderingEngine)] + +debug([<prefix][,<destination>]) + This converter is used as debug tool. It takes a capture of the input sample + and sends it to event sink <destination>, which may designate a ring buffer + such as "buf0", as well as "stdout", or "stderr". Available sinks may be + checked at run time by issuing "show events" on the CLI. When not specified, + the output will be "buf0", which may be consulted via the CLI's "show events" + command. An optional prefix <prefix> may be passed to help distinguish + outputs from multiple expressions. It will then appear before the colon in + the output message. The input sample is passed as-is on the output, so that + it is safe to insert the debug converter anywhere in a chain, even with non- + printable sample types. + + Example: + tcp-request connection track-sc0 src,debug(track-sc) + +digest(<algorithm>) + Converts a binary input sample to a message digest. The result is a binary + sample. The <algorithm> must be an OpenSSL message digest name (e.g. sha256). + + Please note that this converter is only available when HAProxy has been + compiled with USE_OPENSSL. + +div(<value>) + Divides the input value of type signed integer by <value>, and returns the + result as an signed integer. If <value> is null, the largest unsigned + integer is returned (typically 2^63-1). <value> can be a numeric value or a + variable name. The name of the variable starts with an indication about its + scope. The scopes allowed are: + "proc" : the variable is shared with the whole process + "sess" : the variable is shared with the whole session + "txn" : the variable is shared with the transaction (request and response) + "req" : the variable is shared only during request processing + "res" : the variable is shared only during response processing + This prefix is followed by a name. The separator is a '.'. The name may only + contain characters 'a-z', 'A-Z', '0-9', '.' and '_'. + +djb2([<avalanche>]) + Hashes a binary input sample into an unsigned 32-bit quantity using the DJB2 + hash function. Optionally, it is possible to apply a full avalanche hash + function to the output if the optional <avalanche> argument equals 1. This + converter uses the same functions as used by the various hash-based load + balancing algorithms, so it will provide exactly the same results. It is + mostly intended for debugging, but can be used as a stick-table entry to + collect rough statistics. It must not be used for security purposes as a + 32-bit hash is trivial to break. See also "crc32", "sdbm", "wt6", "crc32c", + and the "hash-type" directive. + +even + Returns a boolean TRUE if the input value of type signed integer is even + otherwise returns FALSE. It is functionally equivalent to "not,and(1),bool". + +field(<index>,<delimiters>[,<count>]) + Extracts the substring at the given index counting from the beginning + (positive index) or from the end (negative index) considering given delimiters + from an input string. Indexes start at 1 or -1 and delimiters are a string + formatted list of chars. Optionally you can specify <count> of fields to + extract (default: 1). Value of 0 indicates extraction of all remaining + fields. + + Example : + str(f1_f2_f3__f5),field(5,_) # f5 + str(f1_f2_f3__f5),field(2,_,0) # f2_f3__f5 + str(f1_f2_f3__f5),field(2,_,2) # f2_f3 + str(f1_f2_f3__f5),field(-2,_,3) # f2_f3_ + str(f1_f2_f3__f5),field(-3,_,0) # f1_f2_f3 + +fix_is_valid + Parses a binary payload and performs sanity checks regarding FIX (Financial + Information eXchange): + + - checks that all tag IDs and values are not empty and the tags IDs are well + numeric + - checks the BeginString tag is the first tag with a valid FIX version + - checks the BodyLength tag is the second one with the right body length + - checks the MsgType tag is the third tag. + - checks that last tag in the message is the CheckSum tag with a valid + checksum + + Due to current HAProxy design, only the first message sent by the client and + the server can be parsed. + + This converter returns a boolean, true if the payload contains a valid FIX + message, false if not. + + See also the fix_tag_value converter. + + Example: + tcp-request inspect-delay 10s + tcp-request content reject unless { req.payload(0,0),fix_is_valid } + +fix_tag_value(<tag>) + Parses a FIX (Financial Information eXchange) message and extracts the value + from the tag <tag>. <tag> can be a string or an integer pointing to the + desired tag. Any integer value is accepted, but only the following strings + are translated into their integer equivalent: BeginString, BodyLength, + MsgType, SenderCompID, TargetCompID, CheckSum. More tag names can be easily + added. + + Due to current HAProxy design, only the first message sent by the client and + the server can be parsed. No message validation is performed by this + converter. It is highly recommended to validate the message first using + fix_is_valid converter. + + See also the fix_is_valid converter. + + Example: + tcp-request inspect-delay 10s + tcp-request content reject unless { req.payload(0,0),fix_is_valid } + # MsgType tag ID is 35, so both lines below will return the same content + tcp-request content set-var(txn.foo) req.payload(0,0),fix_tag_value(35) + tcp-request content set-var(txn.bar) req.payload(0,0),fix_tag_value(MsgType) + +hex + Converts a binary input sample to a hex string containing two hex digits per + input byte. It is used to log or transfer hex dumps of some binary input data + in a way that can be reliably transferred (e.g. an SSL ID can be copied in a + header). + +hex2i + Converts a hex string containing two hex digits per input byte to an + integer. If the input value cannot be converted, then zero is returned. + +htonl + Converts the input integer value to its 32-bit binary representation in the + network byte order. Because sample fetches own signed 64-bit integer, when + this converter is used, the input integer value is first casted to an + unsigned 32-bit integer. + +hmac(<algorithm>,<key>) + Converts a binary input sample to a message authentication code with the given + key. The result is a binary sample. The <algorithm> must be one of the + registered OpenSSL message digest names (e.g. sha256). The <key> parameter must + be base64 encoded and can either be a string or a variable. + + Please note that this converter is only available when HAProxy has been + compiled with USE_OPENSSL. + +host_only + Converts a string which contains a Host header value and removes its port. + The input must respect the format of the host header value + (rfc9110#section-7.2). It will support that kind of input: hostname, + hostname:80, 127.0.0.1, 127.0.0.1:80, [::1], [::1]:80. + + This converter also sets the string in lowercase. + + See also: "port_only" converter which will return the port. + +http_date([<offset],[<unit>]) + Converts an integer supposed to contain a date since epoch to a string + representing this date in a format suitable for use in HTTP header fields. If + an offset value is specified, then it is added to the date before the + conversion is operated. This is particularly useful to emit Date header fields, + Expires values in responses when combined with a positive offset, or + Last-Modified values when the offset is negative. + If a unit value is specified, then consider the timestamp as either + "s" for seconds (default behavior), "ms" for milliseconds, or "us" for + microseconds since epoch. Offset is assumed to have the same unit as + input timestamp. + +iif(<true>,<false>) + Returns the <true> string if the input value is true. Returns the <false> + string otherwise. + + Example: + http-request set-header x-forwarded-proto %[ssl_fc,iif(https,http)] + +in_table(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, a boolean false + is returned. Otherwise a boolean true is returned. This can be used to verify + the presence of a certain key in a table tracking some elements (e.g. whether + or not a source IP address or an Authorization header was already seen). + +ipmask(<mask4>,[<mask6>]) + Apply a mask to an IP address, and use the result for lookups and storage. + This can be used to make all hosts within a certain mask to share the same + table entries and as such use the same server. The mask4 can be passed in + dotted form (e.g. 255.255.255.0) or in CIDR form (e.g. 24). The mask6 can + be passed in quadruplet form (e.g. ffff:ffff::) or in CIDR form (e.g. 64). + If no mask6 is given IPv6 addresses will fail to convert for backwards + compatibility reasons. + +json([<input-code>]) + Escapes the input string and produces an ASCII output string ready to use as a + JSON string. The converter tries to decode the input string according to the + <input-code> parameter. It can be "ascii", "utf8", "utf8s", "utf8p" or + "utf8ps". The "ascii" decoder never fails. The "utf8" decoder detects 3 types + of errors: + - bad UTF-8 sequence (lone continuation byte, bad number of continuation + bytes, ...) + - invalid range (the decoded value is within a UTF-8 prohibited range), + - code overlong (the value is encoded with more bytes than necessary). + + The UTF-8 JSON encoding can produce a "too long value" error when the UTF-8 + character is greater than 0xffff because the JSON string escape specification + only authorizes 4 hex digits for the value encoding. The UTF-8 decoder exists + in 4 variants designated by a combination of two suffix letters : "p" for + "permissive" and "s" for "silently ignore". The behaviors of the decoders + are : + - "ascii" : never fails; + - "utf8" : fails on any detected errors; + - "utf8s" : never fails, but removes characters corresponding to errors; + - "utf8p" : accepts and fixes the overlong errors, but fails on any other + error; + - "utf8ps" : never fails, accepts and fixes the overlong errors, but removes + characters corresponding to the other errors. + + This converter is particularly useful for building properly escaped JSON for + logging to servers which consume JSON-formatted traffic logs. + + Example: + capture request header Host len 15 + capture request header user-agent len 150 + log-format '{"ip":"%[src]","user-agent":"%[capture.req.hdr(1),json(utf8s)]"}' + + Input request from client 127.0.0.1: + GET / HTTP/1.0 + User-Agent: Very "Ugly" UA 1/2 + + Output log: + {"ip":"127.0.0.1","user-agent":"Very \"Ugly\" UA 1\/2"} + +json_query(<json_path>,[<output_type>]) + The json_query converter supports the JSON types string, boolean and + number. Floating point numbers will be returned as a string. By + specifying the output_type 'int' the value will be converted to an + Integer. If conversion is not possible the json_query converter fails. + + <json_path> must be a valid JSON Path string as defined in + https://datatracker.ietf.org/doc/draft-ietf-jsonpath-base/ + + Example: + # get a integer value from the request body + # "{"integer":4}" => 5 + http-request set-var(txn.pay_int) req.body,json_query('$.integer','int'),add(1) + + # get a key with '.' in the name + # {"my.key":"myvalue"} => myvalue + http-request set-var(txn.pay_mykey) req.body,json_query('$.my\\.key') + + # {"boolean-false":false} => 0 + http-request set-var(txn.pay_boolean_false) req.body,json_query('$.boolean-false') + + # get the value of the key 'iss' from a JWT Bearer token + http-request set-var(txn.token_payload) req.hdr(Authorization),word(2,.),ub64dec,json_query('$.iss') + +jwt_header_query([<json_path>],[<output_type>]) + When given a JSON Web Token (JWT) in input, either returns the decoded header + part of the token (the first base64-url encoded part of the JWT) if no + parameter is given, or performs a json_query on the decoded header part of + the token. See "json_query" converter for details about the accepted + json_path and output_type parameters. + + Please note that this converter is only available when HAProxy has been + compiled with USE_OPENSSL. + +jwt_payload_query([<json_path>],[<output_type>]) + When given a JSON Web Token (JWT) in input, either returns the decoded + payload part of the token (the second base64-url encoded part of the JWT) if + no parameter is given, or performs a json_query on the decoded payload part + of the token. See "json_query" converter for details about the accepted + json_path and output_type parameters. + + Please note that this converter is only available when HAProxy has been + compiled with USE_OPENSSL. + +jwt_verify(<alg>,<key>) + Performs a signature verification for the JSON Web Token (JWT) given in input + by using the <alg> algorithm and the <key> parameter, which should either + hold a secret or a path to a public certificate. Returns 1 in case of + verification success, 0 in case of verification error and a strictly negative + value for any other error. Because of all those non-null error return values, + the result of this converter should never be converted to a boolean. See + below for a full list of the possible return values. + + For now, only JWS tokens using the Compact Serialization format can be + processed (three dot-separated base64-url encoded strings). Among the + accepted algorithms for a JWS (see section 3.1 of RFC7518), the PSXXX ones + are not managed yet. + + If the used algorithm is of the HMAC family, <key> should be the secret used + in the HMAC signature calculation. Otherwise, <key> should be the path to the + public certificate that can be used to validate the token's signature. All + the certificates that might be used to verify JWTs must be known during init + in order to be added into a dedicated certificate cache so that no disk + access is required during runtime. For this reason, any used certificate must + be mentioned explicitly at least once in a jwt_verify call. Passing an + intermediate variable as second parameter is then not advised. + + This converter only verifies the signature of the token and does not perform + a full JWT validation as specified in section 7.2 of RFC7519. We do not + ensure that the header and payload contents are fully valid JSON's once + decoded for instance, and no checks are performed regarding their respective + contents. + + The possible return values are the following : + + +----+----------------------------------------------------------------------+ + | ID | message | + +----+----------------------------------------------------------------------+ + | 0 | "Verification failure" | + | 1 | "Verification success" | + | -1 | "Unknown algorithm (not mentioned in RFC7518)" | + | -2 | "Unmanaged algorithm (PSXXX algorithm family)" | + | -3 | "Invalid token" | + | -4 | "Out of memory" | + | -5 | "Unknown certificate" | + +----+----------------------------------------------------------------------+ + + Please note that this converter is only available when HAProxy has been + compiled with USE_OPENSSL. + + Example: + # Get a JWT from the authorization header, extract the "alg" field of its + # JOSE header and use a public certificate to verify a signature + http-request set-var(txn.bearer) http_auth_bearer + http-request set-var(txn.jwt_alg) var(txn.bearer),jwt_header_query('$.alg') + http-request deny unless { var(txn.jwt_alg) "RS256" } + http-request deny unless { var(txn.bearer),jwt_verify(txn.jwt_alg,"/path/to/crt.pem") 1 } + +language(<value>[,<default>]) + Returns the value with the highest q-factor from a list as extracted from the + "accept-language" header using "req.fhdr". Values with no q-factor have a + q-factor of 1. Values with a q-factor of 0 are dropped. Only values which + belong to the list of semi-colon delimited <values> will be considered. The + argument <value> syntax is "lang[;lang[;lang[;...]]]". If no value matches the + given list and a default value is provided, it is returned. Note that language + names may have a variant after a dash ('-'). If this variant is present in the + list, it will be matched, but if it is not, only the base language is checked. + The match is case-sensitive, and the output string is always one of those + provided in arguments. The ordering of arguments is meaningless, only the + ordering of the values in the request counts, as the first value among + multiple sharing the same q-factor is used. + + Example : + + # this configuration switches to the backend matching a + # given language based on the request : + + acl es req.fhdr(accept-language),language(es;fr;en) -m str es + acl fr req.fhdr(accept-language),language(es;fr;en) -m str fr + acl en req.fhdr(accept-language),language(es;fr;en) -m str en + use_backend spanish if es + use_backend french if fr + use_backend english if en + default_backend choose_your_language + +length + Get the length of the string. This can only be placed after a string + sample fetch function or after a transformation keyword returning a string + type. The result is of type integer. + +lower + Convert a string sample to lower case. This can only be placed after a string + sample fetch function or after a transformation keyword returning a string + type. The result is of type string. + +ltime(<format>[,<offset>]) + Converts an integer supposed to contain a date since epoch to a string + representing this date in local time using a format defined by the <format> + string using strftime(3). The purpose is to allow any date format to be used + in logs. An optional <offset> in seconds may be applied to the input date + (positive or negative). See the strftime() man page for the format supported + by your operating system. See also the utime converter. + + Example : + + # Emit two colons, one with the local time and another with ip:port + # e.g. 20140710162350 127.0.0.1:57325 + log-format %[date,ltime(%Y%m%d%H%M%S)]\ %ci:%cp + +ltrim(<chars>) + Skips any characters from <chars> from the beginning of the string + representation of the input sample. + +map(<map_file>[,<default_value>]) +map_<match_type>(<map_file>[,<default_value>]) +map_<match_type>_<output_type>(<map_file>[,<default_value>]) + Search the input value from <map_file> using the <match_type> matching method, + and return the associated value converted to the type <output_type>. If the + input value cannot be found in the <map_file>, the converter returns the + <default_value>. If the <default_value> is not set, the converter fails and + acts as if no input value could be fetched. If the <match_type> is not set, it + defaults to "str". Likewise, if the <output_type> is not set, it defaults to + "str". For convenience, the "map" keyword is an alias for "map_str" and maps a + string to another string. + + It is important to avoid overlapping between the keys : IP addresses and + strings are stored in trees, so the first of the finest match will be used. + Other keys are stored in lists, so the first matching occurrence will be used. + + The following array contains the list of all map functions available sorted by + input type, match type and output type. + + input type | match method | output type str | output type int | output type ip + -----------+--------------+-----------------+-----------------+--------------- + str | str | map_str | map_str_int | map_str_ip + -----------+--------------+-----------------+-----------------+--------------- + str | beg | map_beg | map_beg_int | map_end_ip + -----------+--------------+-----------------+-----------------+--------------- + str | sub | map_sub | map_sub_int | map_sub_ip + -----------+--------------+-----------------+-----------------+--------------- + str | dir | map_dir | map_dir_int | map_dir_ip + -----------+--------------+-----------------+-----------------+--------------- + str | dom | map_dom | map_dom_int | map_dom_ip + -----------+--------------+-----------------+-----------------+--------------- + str | end | map_end | map_end_int | map_end_ip + -----------+--------------+-----------------+-----------------+--------------- + str | reg | map_reg | map_reg_int | map_reg_ip + -----------+--------------+-----------------+-----------------+--------------- + str | reg | map_regm | map_reg_int | map_reg_ip + -----------+--------------+-----------------+-----------------+--------------- + int | int | map_int | map_int_int | map_int_ip + -----------+--------------+-----------------+-----------------+--------------- + ip | ip | map_ip | map_ip_int | map_ip_ip + -----------+--------------+-----------------+-----------------+--------------- + + The special map called "map_regm" expect matching zone in the regular + expression and modify the output replacing back reference (like "\1") by + the corresponding match text. + + The file contains one key + value per line. Lines which start with '#' are + ignored, just like empty lines. Leading tabs and spaces are stripped. The key + is then the first "word" (series of non-space/tabs characters), and the value + is what follows this series of space/tab till the end of the line excluding + trailing spaces/tabs. + + Example : + + # this is a comment and is ignored + 2.22.246.0/23 United Kingdom \n + <-><-----------><--><------------><----> + | | | | `- trailing spaces ignored + | | | `---------- value + | | `-------------------- middle spaces ignored + | `---------------------------- key + `------------------------------------ leading spaces ignored + +mod(<value>) + Divides the input value of type signed integer by <value>, and returns the + remainder as an signed integer. If <value> is null, then zero is returned. + <value> can be a numeric value or a variable name. The name of the variable + starts with an indication about its scope. The scopes allowed are: + "proc" : the variable is shared with the whole process + "sess" : the variable is shared with the whole session + "txn" : the variable is shared with the transaction (request and response) + "req" : the variable is shared only during request processing + "res" : the variable is shared only during response processing + This prefix is followed by a name. The separator is a '.'. The name may only + contain characters 'a-z', 'A-Z', '0-9', '.' and '_'. + +mqtt_field_value(<packettype>,<fieldname_or_property_ID>) + Returns value of <fieldname> found in input MQTT payload of type + <packettype>. + <packettype> can be either a string (case insensitive matching) or a numeric + value corresponding to the type of packet we're supposed to extract data + from. + Supported string and integers can be found here: + https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718021 + https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901022 + + <fieldname> depends on <packettype> and can be any of the following below. + (note that <fieldname> matching is case insensitive). + <property id> can only be found in MQTT v5.0 streams. check this table: + https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901029 + + - CONNECT (or 1): flags, protocol_name, protocol_version, client_identifier, + will_topic, will_payload, username, password, keepalive + OR any property ID as a numeric value (for MQTT v5.0 + packets only): + 17: Session Expiry Interval + 33: Receive Maximum + 39: Maximum Packet Size + 34: Topic Alias Maximum + 25: Request Response Information + 23: Request Problem Information + 21: Authentication Method + 22: Authentication Data + 18: Will Delay Interval + 1: Payload Format Indicator + 2: Message Expiry Interval + 3: Content Type + 8: Response Topic + 9: Correlation Data + Not supported yet: + 38: User Property + + - CONNACK (or 2): flags, protocol_version, reason_code + OR any property ID as a numeric value (for MQTT v5.0 + packets only): + 17: Session Expiry Interval + 33: Receive Maximum + 36: Maximum QoS + 37: Retain Available + 39: Maximum Packet Size + 18: Assigned Client Identifier + 34: Topic Alias Maximum + 31: Reason String + 40; Wildcard Subscription Available + 41: Subscription Identifiers Available + 42: Shared Subscription Available + 19: Server Keep Alive + 26: Response Information + 28: Server Reference + 21: Authentication Method + 22: Authentication Data + Not supported yet: + 38: User Property + + Due to current HAProxy design, only the first message sent by the client and + the server can be parsed. Thus this converter can extract data only from + CONNECT and CONNACK packet types. CONNECT is the first message sent by the + client and CONNACK is the first response sent by the server. + + Example: + + acl data_in_buffer req.len ge 4 + tcp-request content set-var(txn.username) \ + req.payload(0,0),mqtt_field_value(connect,protocol_name) \ + if data_in_buffer + # do the same as above + tcp-request content set-var(txn.username) \ + req.payload(0,0),mqtt_field_value(1,protocol_name) \ + if data_in_buffer + +mqtt_is_valid + Checks that the binary input is a valid MQTT packet. It returns a boolean. + + Due to current HAProxy design, only the first message sent by the client and + the server can be parsed. Thus this converter can extract data only from + CONNECT and CONNACK packet types. CONNECT is the first message sent by the + client and CONNACK is the first response sent by the server. + + Only MQTT 3.1, 3.1.1 and 5.0 are supported. + + Example: + + acl data_in_buffer req.len ge 4 + tcp-request content reject unless { req.payload(0,0),mqtt_is_valid } + +mul(<value>) + Multiplies the input value of type signed integer by <value>, and returns + the product as an signed integer. In case of overflow, the largest possible + value for the sign is returned so that the operation doesn't wrap around. + <value> can be a numeric value or a variable name. The name of the variable + starts with an indication about its scope. The scopes allowed are: + "proc" : the variable is shared with the whole process + "sess" : the variable is shared with the whole session + "txn" : the variable is shared with the transaction (request and response) + "req" : the variable is shared only during request processing + "res" : the variable is shared only during response processing + This prefix is followed by a name. The separator is a '.'. The name may only + contain characters 'a-z', 'A-Z', '0-9', '.' and '_'. + +nbsrv + Takes an input value of type string, interprets it as a backend name and + returns the number of usable servers in that backend. Can be used in places + where we want to look up a backend from a dynamic name, like a result of a + map lookup. + +neg + Takes the input value of type signed integer, computes the opposite value, + and returns the remainder as an signed integer. 0 is identity. This operator + is provided for reversed subtracts : in order to subtract the input from a + constant, simply perform a "neg,add(value)". + +not + Returns a boolean FALSE if the input value of type signed integer is + non-null, otherwise returns TRUE. Used in conjunction with and(), it can be + used to report true/false for bit testing on input values (e.g. verify the + absence of a flag). + +odd + Returns a boolean TRUE if the input value of type signed integer is odd + otherwise returns FALSE. It is functionally equivalent to "and(1),bool". + +or(<value>) + Performs a bitwise "OR" between <value> and the input value of type signed + integer, and returns the result as an signed integer. <value> can be a + numeric value or a variable name. The name of the variable starts with an + indication about its scope. The scopes allowed are: + "proc" : the variable is shared with the whole process + "sess" : the variable is shared with the whole session + "txn" : the variable is shared with the transaction (request and response) + "req" : the variable is shared only during request processing + "res" : the variable is shared only during response processing + This prefix is followed by a name. The separator is a '.'. The name may only + contain characters 'a-z', 'A-Z', '0-9', '.' and '_'. + +port_only + Converts a string which contains a Host header value into an integer by + returning its port. + The input must respect the format of the host header value + (rfc9110#section-7.2). It will support that kind of input: hostname, + hostname:80, 127.0.0.1, 127.0.0.1:80, [::1], [::1]:80. + + If no port were provided in the input, it will return 0. + + See also: "host_only" converter which will return the host. + +protobuf(<field_number>,[<field_type>]) + This extracts the protocol buffers message field in raw mode of an input binary + sample representation of a protocol buffer message with <field_number> as field + number (dotted notation) if <field_type> is not present, or as an integer sample + if this field is present (see also "ungrpc" below). + The list of the authorized types is the following one: "int32", "int64", "uint32", + "uint64", "sint32", "sint64", "bool", "enum" for the "varint" wire type 0 + "fixed64", "sfixed64", "double" for the 64bit wire type 1, "fixed32", "sfixed32", + "float" for the wire type 5. Note that "string" is considered as a length-delimited + type, so it does not require any <field_type> argument to be extracted. + More information may be found here about the protocol buffers message field types: + https://developers.google.com/protocol-buffers/docs/encoding + +regsub(<regex>,<subst>[,<flags>]) + Applies a regex-based substitution to the input string. It does the same + operation as the well-known "sed" utility with "s/<regex>/<subst>/". By + default it will replace in the input string the first occurrence of the + largest part matching the regular expression <regex> with the substitution + string <subst>. It is possible to replace all occurrences instead by adding + the flag "g" in the third argument <flags>. It is also possible to make the + regex case insensitive by adding the flag "i" in <flags>. Since <flags> is a + string, it is made up from the concatenation of all desired flags. Thus if + both "i" and "g" are desired, using "gi" or "ig" will have the same effect. + The first use of this converter is to replace certain characters or sequence + of characters with other ones. + + It is highly recommended to enclose the regex part using protected quotes to + improve clarity and never have a closing parenthesis from the regex mixed up + with the parenthesis from the function. Just like in Bourne shell, the first + level of quotes is processed when delimiting word groups on the line, a + second level is usable for argument. It is recommended to use single quotes + outside since these ones do not try to resolve backslashes nor dollar signs. + + Examples: + + # de-duplicate "/" in header "x-path". + # input: x-path: /////a///b/c/xzxyz/ + # output: x-path: /a/b/c/xzxyz/ + http-request set-header x-path "%[hdr(x-path),regsub('/+','/','g')]" + + # copy query string to x-query and drop all leading '?', ';' and '&' + http-request set-header x-query "%[query,regsub([?;&]*,'')]" + + # capture groups and backreferences + # both lines do the same. + http-request redirect location %[url,'regsub("(foo|bar)([0-9]+)?","\2\1",i)'] + http-request redirect location %[url,regsub(\"(foo|bar)([0-9]+)?\",\"\2\1\",i)] + +capture-req(<id>) + Capture the string entry in the request slot <id> and returns the entry as + is. If the slot doesn't exist, the capture fails silently. + + See also: "declare capture", "http-request capture", + "http-response capture", "capture.req.hdr" and + "capture.res.hdr" (sample fetches). + +capture-res(<id>) + Capture the string entry in the response slot <id> and returns the entry as + is. If the slot doesn't exist, the capture fails silently. + + See also: "declare capture", "http-request capture", + "http-response capture", "capture.req.hdr" and + "capture.res.hdr" (sample fetches). + +rtrim(<chars>) + Skips any characters from <chars> from the end of the string representation + of the input sample. + +sdbm([<avalanche>]) + Hashes a binary input sample into an unsigned 32-bit quantity using the SDBM + hash function. Optionally, it is possible to apply a full avalanche hash + function to the output if the optional <avalanche> argument equals 1. This + converter uses the same functions as used by the various hash-based load + balancing algorithms, so it will provide exactly the same results. It is + mostly intended for debugging, but can be used as a stick-table entry to + collect rough statistics. It must not be used for security purposes as a + 32-bit hash is trivial to break. See also "crc32", "djb2", "wt6", "crc32c", + and the "hash-type" directive. + +secure_memcmp(<var>) + Compares the contents of <var> with the input value. Both values are treated + as a binary string. Returns a boolean indicating whether both binary strings + match. + + If both binary strings have the same length then the comparison will be + performed in constant time. + + Please note that this converter is only available when HAProxy has been + compiled with USE_OPENSSL. + + Example : + + http-request set-var(txn.token) hdr(token) + # Check whether the token sent by the client matches the secret token + # value, without leaking the contents using a timing attack. + acl token_given str(my_secret_token),secure_memcmp(txn.token) + +set-var(<var>[,<cond>...]) + Sets a variable with the input content and returns the content on the output + as-is if all of the specified conditions are true (see below for a list of + possible conditions). The variable keeps the value and the associated input + type. The name of the variable starts with an indication about its scope. The + scopes allowed are: + "proc" : the variable is shared with the whole process + "sess" : the variable is shared with the whole session + "txn" : the variable is shared with the transaction (request and + response), + "req" : the variable is shared only during request processing, + "res" : the variable is shared only during response processing. + This prefix is followed by a name. The separator is a '.'. The name may only + contain characters 'a-z', 'A-Z', '0-9', '.' and '_'. + + You can pass at most four conditions to the converter among the following + possible conditions : + - "ifexists"/"ifnotexists": + Checks if the variable already existed before the current set-var call. + A variable is usually created through a successful set-var call. + Note that variables of scope "proc" are created during configuration + parsing so the "ifexists" condition will always be true for them. + - "ifempty"/"ifnotempty": + Checks if the input is empty or not. + Scalar types are never empty so the ifempty condition will be false for + them regardless of the input's contents (integers, booleans, IPs ...). + - "ifset"/"ifnotset": + Checks if the variable was previously set or not, or if unset-var was + called on the variable. + A variable that does not exist yet is considered as not set. A "proc" + variable can exist while not being set since they are created during + configuration parsing. + - "ifgt"/"iflt": + Checks if the content of the variable is "greater than" or "less than" + the input. This check can only be performed if both the input and + the variable are of type integer. Otherwise, the check is considered as + true by default. + +sha1 + Converts a binary input sample to a SHA-1 digest. The result is a binary + sample with length of 20 bytes. + +sha2([<bits>]) + Converts a binary input sample to a digest in the SHA-2 family. The result + is a binary sample with length of <bits>/8 bytes. + + Valid values for <bits> are 224, 256, 384, 512, each corresponding to + SHA-<bits>. The default value is 256. + + Please note that this converter is only available when HAProxy has been + compiled with USE_OPENSSL. + +srv_queue + Takes an input value of type string, either a server name or <backend>/<server> + format and returns the number of queued sessions on that server. Can be used + in places where we want to look up queued sessions from a dynamic name, like a + cookie value (e.g. req.cook(SRVID),srv_queue) and then make a decision to break + persistence or direct a request elsewhere. + +strcmp(<var>) + Compares the contents of <var> with the input value of type string. Returns + the result as a signed integer compatible with strcmp(3): 0 if both strings + are identical. A value less than 0 if the left string is lexicographically + smaller than the right string or if the left string is shorter. A value greater + than 0 otherwise (right string greater than left string or the right string is + shorter). + + See also the secure_memcmp converter if you need to compare two binary + strings in constant time. + + Example : + + http-request set-var(txn.host) hdr(host) + # Check whether the client is attempting domain fronting. + acl ssl_sni_http_host_match ssl_fc_sni,strcmp(txn.host) eq 0 + + +sub(<value>) + Subtracts <value> from the input value of type signed integer, and returns + the result as an signed integer. Note: in order to subtract the input from + a constant, simply perform a "neg,add(value)". <value> can be a numeric value + or a variable name. The name of the variable starts with an indication about + its scope. The scopes allowed are: + "proc" : the variable is shared with the whole process + "sess" : the variable is shared with the whole session + "txn" : the variable is shared with the transaction (request and + response), + "req" : the variable is shared only during request processing, + "res" : the variable is shared only during response processing. + This prefix is followed by a name. The separator is a '.'. The name may only + contain characters 'a-z', 'A-Z', '0-9', '.' and '_'. + +table_bytes_in_rate(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the average client-to-server + bytes rate associated with the input sample in the designated table, measured + in amount of bytes over the period configured in the table. See also the + sc_bytes_in_rate sample fetch keyword. + + +table_bytes_out_rate(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the average server-to-client + bytes rate associated with the input sample in the designated table, measured + in amount of bytes over the period configured in the table. See also the + sc_bytes_out_rate sample fetch keyword. + +table_conn_cnt(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the cumulative number of incoming + connections associated with the input sample in the designated table. See + also the sc_conn_cnt sample fetch keyword. + +table_conn_cur(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the current amount of concurrent + tracked connections associated with the input sample in the designated table. + See also the sc_conn_cur sample fetch keyword. + +table_conn_rate(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the average incoming connection + rate associated with the input sample in the designated table. See also the + sc_conn_rate sample fetch keyword. + +table_expire(<table>[,<default_value>]) + Uses the input sample to perform a look up in the specified table. If the key + is not found in the table, the converter fails except if <default_value> is + set: this makes the converter succeed and return <default_value>. If the key + is found the converter returns the key expiration delay associated with the + input sample in the designated table. + See also the table_idle sample fetch keyword. + +table_gpt(<idx>,<table>) + Uses the string representation of the input sample to perform a lookup in + the specified table. If the key is not found in the table, boolean value zero + is returned. Otherwise the converter returns the current value of the general + purpose tag at the index <idx> of the array associated to the input sample + in the designated <table>. <idx> is an integer between 0 and 99. + If there is no GPT stored at this index, it also returns the boolean value 0. + This applies only to the 'gpt' array data_type (and not on the legacy 'gpt0' + data-type). + See also the sc_get_gpt sample fetch keyword. + +table_gpt0(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, boolean value zero + is returned. Otherwise the converter returns the current value of the first + general purpose tag associated with the input sample in the designated table. + See also the sc_get_gpt0 sample fetch keyword. + +table_gpc(<idx>,<table>) + Uses the string representation of the input sample to perform a lookup in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the current value of the + General Purpose Counter at the index <idx> of the array associated + to the input sample in the designated <table>. <idx> is an integer + between 0 and 99. + If there is no GPC stored at this index, it also returns the boolean value 0. + This applies only to the 'gpc' array data_type (and not to the legacy + 'gpc0' nor 'gpc1' data_types). + See also the sc_get_gpc sample fetch keyword. + +table_gpc_rate(<idx>,<table>) + Uses the string representation of the input sample to perform a lookup in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the frequency which the Global + Purpose Counter at index <idx> of the array (associated to the input sample + in the designated stick-table <table>) was incremented over the + configured period. <idx> is an integer between 0 and 99. + If there is no gpc_rate stored at this index, it also returns the boolean + value 0. + This applies only to the 'gpc_rate' array data_type (and not to the + legacy 'gpc0_rate' nor 'gpc1_rate' data_types). + See also the sc_gpc_rate sample fetch keyword. + +table_gpc0(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the current value of the first + general purpose counter associated with the input sample in the designated + table. See also the sc_get_gpc0 sample fetch keyword. + +table_gpc0_rate(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the frequency which the gpc0 + counter was incremented over the configured period in the table, associated + with the input sample in the designated table. See also the sc_get_gpc0_rate + sample fetch keyword. + +table_gpc1(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the current value of the second + general purpose counter associated with the input sample in the designated + table. See also the sc_get_gpc1 sample fetch keyword. + +table_gpc1_rate(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the frequency which the gpc1 + counter was incremented over the configured period in the table, associated + with the input sample in the designated table. See also the sc_get_gpc1_rate + sample fetch keyword. + +table_http_err_cnt(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the cumulative number of HTTP + errors associated with the input sample in the designated table. See also the + sc_http_err_cnt sample fetch keyword. + +table_http_err_rate(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the average rate of HTTP errors associated with the + input sample in the designated table, measured in amount of errors over the + period configured in the table. See also the sc_http_err_rate sample fetch + keyword. + +table_http_fail_cnt(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the cumulative number of HTTP + failures associated with the input sample in the designated table. See also + the sc_http_fail_cnt sample fetch keyword. + +table_http_fail_rate(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the average rate of HTTP failures associated with the + input sample in the designated table, measured in amount of failures over the + period configured in the table. See also the sc_http_fail_rate sample fetch + keyword. + +table_http_req_cnt(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the cumulative number of HTTP + requests associated with the input sample in the designated table. See also + the sc_http_req_cnt sample fetch keyword. + +table_http_req_rate(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the average rate of HTTP requests associated with the + input sample in the designated table, measured in amount of requests over the + period configured in the table. See also the sc_http_req_rate sample fetch + keyword. + +table_idle(<table>[,<default_value>]) + Uses the input sample to perform a look up in the specified table. If the key + is not found in the table, the converter fails except if <default_value> is + set: this makes the converter succeed and return <default_value>. If the key + is found the converter returns the time the key entry associated with the + input sample in the designated table remained idle since the last time it was + updated. + See also the table_expire sample fetch keyword. + +table_kbytes_in(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the cumulative number of client- + to-server data associated with the input sample in the designated table, + measured in kilobytes. The test is currently performed on 32-bit integers, + which limits values to 4 terabytes. See also the sc_kbytes_in sample fetch + keyword. + +table_kbytes_out(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the cumulative number of server- + to-client data associated with the input sample in the designated table, + measured in kilobytes. The test is currently performed on 32-bit integers, + which limits values to 4 terabytes. See also the sc_kbytes_out sample fetch + keyword. + +table_server_id(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the server ID associated with + the input sample in the designated table. A server ID is associated to a + sample by a "stick" rule when a connection to a server succeeds. A server ID + zero means that no server is associated with this key. + +table_sess_cnt(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the cumulative number of incoming + sessions associated with the input sample in the designated table. Note that + a session here refers to an incoming connection being accepted by the + "tcp-request connection" rulesets. See also the sc_sess_cnt sample fetch + keyword. + +table_sess_rate(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the average incoming session + rate associated with the input sample in the designated table. Note that a + session here refers to an incoming connection being accepted by the + "tcp-request connection" rulesets. See also the sc_sess_rate sample fetch + keyword. + +table_trackers(<table>) + Uses the string representation of the input sample to perform a look up in + the specified table. If the key is not found in the table, integer value zero + is returned. Otherwise the converter returns the current amount of concurrent + connections tracking the same key as the input sample in the designated + table. It differs from table_conn_cur in that it does not rely on any stored + information but on the table's reference count (the "use" value which is + returned by "show table" on the CLI). This may sometimes be more suited for + layer7 tracking. It can be used to tell a server how many concurrent + connections there are from a given address for example. See also the + sc_trackers sample fetch keyword. + +ub64dec + This converter is the base64url variant of b64dec converter. base64url + encoding is the "URL and Filename Safe Alphabet" variant of base64 encoding. + It is also the encoding used in JWT (JSON Web Token) standard. + + Example: + # Decoding a JWT payload: + http-request set-var(txn.token_payload) req.hdr(Authorization),word(2,.),ub64dec + +ub64enc + This converter is the base64url variant of base64 converter. + +upper + Convert a string sample to upper case. This can only be placed after a string + sample fetch function or after a transformation keyword returning a string + type. The result is of type string. + +url_dec([<in_form>]) + Takes an url-encoded string provided as input and returns the decoded version + as output. The input and the output are of type string. If the <in_form> + argument is set to a non-zero integer value, the input string is assumed to + be part of a form or query string and the '+' character will be turned into a + space (' '). Otherwise this will only happen after a question mark indicating + a query string ('?'). + +url_enc([<enc_type>]) + Takes a string provided as input and returns the encoded version as output. + The input and the output are of type string. By default the type of encoding + is meant for `query` type. There is no other type supported for now but the + optional argument is here for future changes. + +ungrpc(<field_number>,[<field_type>]) + This extracts the protocol buffers message field in raw mode of an input binary + sample representation of a gRPC message with <field_number> as field number + (dotted notation) if <field_type> is not present, or as an integer sample if this + field is present. + The list of the authorized types is the following one: "int32", "int64", "uint32", + "uint64", "sint32", "sint64", "bool", "enum" for the "varint" wire type 0 + "fixed64", "sfixed64", "double" for the 64bit wire type 1, "fixed32", "sfixed32", + "float" for the wire type 5. Note that "string" is considered as a length-delimited + type, so it does not require any <field_type> argument to be extracted. + More information may be found here about the protocol buffers message field types: + https://developers.google.com/protocol-buffers/docs/encoding + + Example: + // with such a protocol buffer .proto file content adapted from + // https://github.com/grpc/grpc/blob/master/examples/protos/route_guide.proto + + message Point { + int32 latitude = 1; + int32 longitude = 2; + } + + message PPoint { + Point point = 59; + } + + message Rectangle { + // One corner of the rectangle. + PPoint lo = 48; + // The other corner of the rectangle. + PPoint hi = 49; + } + + let's say a body request is made of a "Rectangle" object value (two PPoint + protocol buffers messages), the four protocol buffers fields could be + extracted with these "ungrpc" directives: + + req.body,ungrpc(48.59.1,int32) # "latitude" of "lo" first PPoint + req.body,ungrpc(48.59.2,int32) # "longitude" of "lo" first PPoint + req.body,ungrpc(49.59.1,int32) # "latitude" of "hi" second PPoint + req.body,ungrpc(49.59.2,int32) # "longitude" of "hi" second PPoint + + We could also extract the intermediary 48.59 field as a binary sample as follows: + + req.body,ungrpc(48.59) + + As a gRPC message is always made of a gRPC header followed by protocol buffers + messages, in the previous example the "latitude" of "lo" first PPoint + could be extracted with these equivalent directives: + + req.body,ungrpc(48.59),protobuf(1,int32) + req.body,ungrpc(48),protobuf(59.1,int32) + req.body,ungrpc(48),protobuf(59),protobuf(1,int32) + + Note that the first convert must be "ungrpc", the remaining ones must be + "protobuf" and only the last one may have or not a second argument to + interpret the previous binary sample. + + +unset-var(<var>) + Unsets a variable if the input content is defined. The name of the variable + starts with an indication about its scope. The scopes allowed are: + "proc" : the variable is shared with the whole process + "sess" : the variable is shared with the whole session + "txn" : the variable is shared with the transaction (request and + response), + "req" : the variable is shared only during request processing, + "res" : the variable is shared only during response processing. + This prefix is followed by a name. The separator is a '.'. The name may only + contain characters 'a-z', 'A-Z', '0-9', '.' and '_'. + +utime(<format>[,<offset>]) + Converts an integer supposed to contain a date since epoch to a string + representing this date in UTC time using a format defined by the <format> + string using strftime(3). The purpose is to allow any date format to be used + in logs. An optional <offset> in seconds may be applied to the input date + (positive or negative). See the strftime() man page for the format supported + by your operating system. See also the ltime converter. + + Example : + + # Emit two colons, one with the UTC time and another with ip:port + # e.g. 20140710162350 127.0.0.1:57325 + log-format %[date,utime(%Y%m%d%H%M%S)]\ %ci:%cp + +word(<index>,<delimiters>[,<count>]) + Extracts the nth word counting from the beginning (positive index) or from + the end (negative index) considering given delimiters from an input string. + Indexes start at 1 or -1 and delimiters are a string formatted list of chars. + Delimiters at the beginning or end of the input string are ignored. + Optionally you can specify <count> of words to extract (default: 1). + Value of 0 indicates extraction of all remaining words. + + Example : + str(f1_f2_f3__f5),word(4,_) # f5 + str(f1_f2_f3__f5),word(2,_,0) # f2_f3__f5 + str(f1_f2_f3__f5),word(3,_,2) # f3__f5 + str(f1_f2_f3__f5),word(-2,_,3) # f1_f2_f3 + str(f1_f2_f3__f5),word(-3,_,0) # f1_f2 + str(/f1/f2/f3/f4),word(1,/) # f1 + +wt6([<avalanche>]) + Hashes a binary input sample into an unsigned 32-bit quantity using the WT6 + hash function. Optionally, it is possible to apply a full avalanche hash + function to the output if the optional <avalanche> argument equals 1. This + converter uses the same functions as used by the various hash-based load + balancing algorithms, so it will provide exactly the same results. It is + mostly intended for debugging, but can be used as a stick-table entry to + collect rough statistics. It must not be used for security purposes as a + 32-bit hash is trivial to break. See also "crc32", "djb2", "sdbm", "crc32c", + and the "hash-type" directive. + +xor(<value>) + Performs a bitwise "XOR" (exclusive OR) between <value> and the input value + of type signed integer, and returns the result as an signed integer. + <value> can be a numeric value or a variable name. The name of the variable + starts with an indication about its scope. The scopes allowed are: + "proc" : the variable is shared with the whole process + "sess" : the variable is shared with the whole session + "txn" : the variable is shared with the transaction (request and + response), + "req" : the variable is shared only during request processing, + "res" : the variable is shared only during response processing. + This prefix is followed by a name. The separator is a '.'. The name may only + contain characters 'a-z', 'A-Z', '0-9', '.' and '_'. + +xxh3([<seed>]) + Hashes a binary input sample into a signed 64-bit quantity using the XXH3 + 64-bit variant of the XXhash hash function. This hash supports a seed which + defaults to zero but a different value maybe passed as the <seed> argument. + This hash is known to be very good and very fast so it can be used to hash + URLs and/or URL parameters for use as stick-table keys to collect statistics + with a low collision rate, though care must be taken as the algorithm is not + considered as cryptographically secure. + +xxh32([<seed>]) + Hashes a binary input sample into an unsigned 32-bit quantity using the 32-bit + variant of the XXHash hash function. This hash supports a seed which defaults + to zero but a different value maybe passed as the <seed> argument. This hash + is known to be very good and very fast so it can be used to hash URLs and/or + URL parameters for use as stick-table keys to collect statistics with a low + collision rate, though care must be taken as the algorithm is not considered + as cryptographically secure. + +xxh64([<seed>]) + Hashes a binary input sample into a signed 64-bit quantity using the 64-bit + variant of the XXHash hash function. This hash supports a seed which defaults + to zero but a different value maybe passed as the <seed> argument. This hash + is known to be very good and very fast so it can be used to hash URLs and/or + URL parameters for use as stick-table keys to collect statistics with a low + collision rate, though care must be taken as the algorithm is not considered + as cryptographically secure. + + +7.3.2. Fetching samples from internal states +-------------------------------------------- + +A first set of sample fetch methods applies to internal information which does +not even relate to any client information. These ones are sometimes used with +"monitor-fail" directives to report an internal status to external watchers. +The sample fetch methods described in this section are usable anywhere. + +always_false : boolean + Always returns the boolean "false" value. It may be used with ACLs as a + temporary replacement for another one when adjusting configurations. + +always_true : boolean + Always returns the boolean "true" value. It may be used with ACLs as a + temporary replacement for another one when adjusting configurations. + +avg_queue([<backend>]) : integer + Returns the total number of queued connections of the designated backend + divided by the number of active servers. The current backend is used if no + backend is specified. This is very similar to "queue" except that the size of + the farm is considered, in order to give a more accurate measurement of the + time it may take for a new connection to be processed. The main usage is with + ACL to return a sorry page to new users when it becomes certain they will get + a degraded service, or to pass to the backend servers in a header so that + they decide to work in degraded mode or to disable some functions to speed up + the processing a bit. Note that in the event there would not be any active + server anymore, twice the number of queued connections would be considered as + the measured value. This is a fair estimate, as we expect one server to get + back soon anyway, but we still prefer to send new traffic to another backend + if in better shape. See also the "queue", "be_conn", and "be_sess_rate" + sample fetches. + +be_conn([<backend>]) : integer + Applies to the number of currently established connections on the backend, + possibly including the connection being evaluated. If no backend name is + specified, the current one is used. But it is also possible to check another + backend. It can be used to use a specific farm when the nominal one is full. + See also the "fe_conn", "queue", "be_conn_free", and "be_sess_rate" criteria. + +be_conn_free([<backend>]) : integer + Returns an integer value corresponding to the number of available connections + across available servers in the backend. Queue slots are not included. Backup + servers are also not included, unless all other servers are down. If no + backend name is specified, the current one is used. But it is also possible + to check another backend. It can be used to use a specific farm when the + nominal one is full. See also the "be_conn", "connslots", and "srv_conn_free" + criteria. + + OTHER CAVEATS AND NOTES: if any of the server maxconn, or maxqueue is 0 + (meaning unlimited), then this fetch clearly does not make sense, in which + case the value returned will be -1. + +be_sess_rate([<backend>]) : integer + Returns an integer value corresponding to the sessions creation rate on the + backend, in number of new sessions per second. This is used with ACLs to + switch to an alternate backend when an expensive or fragile one reaches too + high a session rate, or to limit abuse of service (e.g. prevent sucking of an + online dictionary). It can also be useful to add this element to logs using a + log-format directive. + + Example : + # Redirect to an error page if the dictionary is requested too often + backend dynamic + mode http + acl being_scanned be_sess_rate gt 100 + redirect location /denied.html if being_scanned + +bin(<hex>) : bin + Returns a binary chain. The input is the hexadecimal representation + of the string. + +bool(<bool>) : bool + Returns a boolean value. <bool> can be 'true', 'false', '1' or '0'. + 'false' and '0' are the same. 'true' and '1' are the same. + +connslots([<backend>]) : integer + Returns an integer value corresponding to the number of connection slots + still available in the backend, by totaling the maximum amount of + connections on all servers and the maximum queue size. This is probably only + used with ACLs. + + The basic idea here is to be able to measure the number of connection "slots" + still available (connection + queue), so that anything beyond that (intended + usage; see "use_backend" keyword) can be redirected to a different backend. + + 'connslots' = number of available server connection slots, + number of + available server queue slots. + + Note that while "fe_conn" may be used, "connslots" comes in especially + useful when you have a case of traffic going to one single ip, splitting into + multiple backends (perhaps using ACLs to do name-based load balancing) and + you want to be able to differentiate between different backends, and their + available "connslots". Also, whereas "nbsrv" only measures servers that are + actually *down*, this fetch is more fine-grained and looks into the number of + available connection slots as well. See also "queue" and "avg_queue". + + OTHER CAVEATS AND NOTES: at this point in time, the code does not take care + of dynamic connections. Also, if any of the server maxconn, or maxqueue is 0, + then this fetch clearly does not make sense, in which case the value returned + will be -1. + +cpu_calls : integer + Returns the number of calls to the task processing the stream or current + request since it was allocated. This number is reset for each new request on + the same connections in case of HTTP keep-alive. This value should usually be + low and stable (around 2 calls for a typically simple request) but may become + high if some processing (compression, caching or analysis) is performed. This + is purely for performance monitoring purposes. + +cpu_ns_avg : integer + Returns the average number of nanoseconds spent in each call to the task + processing the stream or current request. This number is reset for each new + request on the same connections in case of HTTP keep-alive. This value + indicates the overall cost of processing the request or the connection for + each call. There is no good nor bad value but the time spent in a call + automatically causes latency for other processing (see lat_ns_avg below), + and may affect other connection's apparent response time. Certain operations + like compression, complex regex matching or heavy Lua operations may directly + affect this value, and having it in the logs will make it easier to spot the + faulty processing that needs to be fixed to recover decent performance. + Note: this value is exactly cpu_ns_tot divided by cpu_calls. + +cpu_ns_tot : integer + Returns the total number of nanoseconds spent in each call to the task + processing the stream or current request. This number is reset for each new + request on the same connections in case of HTTP keep-alive. This value + indicates the overall cost of processing the request or the connection for + each call. There is no good nor bad value but the time spent in a call + automatically causes latency for other processing (see lat_ns_avg below), + induces CPU costs on the machine, and may affect other connection's apparent + response time. Certain operations like compression, complex regex matching or + heavy Lua operations may directly affect this value, and having it in the + logs will make it easier to spot the faulty processing that needs to be fixed + to recover decent performance. The value may be artificially high due to a + high cpu_calls count, for example when processing many HTTP chunks, and for + this reason it is often preferred to log cpu_ns_avg instead. + +date([<offset>],[<unit>]) : integer + Returns the current date as the epoch (number of seconds since 01/01/1970). + + If an offset value is specified, then it is added to the current date before + returning the value. This is particularly useful to compute relative dates, + as both positive and negative offsets are allowed. + It is useful combined with the http_date converter. + + <unit> is facultative, and can be set to "s" for seconds (default behavior), + "ms" for milliseconds or "us" for microseconds. + If unit is set, return value is an integer reflecting either seconds, + milliseconds or microseconds since epoch, plus offset. + It is useful when a time resolution of less than a second is needed. + + Example : + + # set an expires header to now+1 hour in every response + http-response set-header Expires %[date(3600),http_date] + + # set an expires header to now+1 hour in every response, with + # millisecond granularity + http-response set-header Expires %[date(3600000,ms),http_date(0,ms)] + +date_us : integer + Return the microseconds part of the date (the "second" part is returned by + date sample). This sample is coherent with the date sample as it is comes + from the same timeval structure. + +env(<name>) : string + Returns a string containing the value of environment variable <name>. As a + reminder, environment variables are per-process and are sampled when the + process starts. This can be useful to pass some information to a next hop + server, or with ACLs to take specific action when the process is started a + certain way. + + Examples : + # Pass the Via header to next hop with the local hostname in it + http-request add-header Via 1.1\ %[env(HOSTNAME)] + + # reject cookie-less requests when the STOP environment variable is set + http-request deny if !{ req.cook(SESSIONID) -m found } { env(STOP) -m found } + +fe_conn([<frontend>]) : integer + Returns the number of currently established connections on the frontend, + possibly including the connection being evaluated. If no frontend name is + specified, the current one is used. But it is also possible to check another + frontend. It can be used to return a sorry page before hard-blocking, or to + use a specific backend to drain new requests when the farm is considered + full. This is mostly used with ACLs but can also be used to pass some + statistics to servers in HTTP headers. See also the "dst_conn", "be_conn", + "fe_sess_rate" fetches. + +fe_req_rate([<frontend>]) : integer + Returns an integer value corresponding to the number of HTTP requests per + second sent to a frontend. This number can differ from "fe_sess_rate" in + situations where client-side keep-alive is enabled. + +fe_sess_rate([<frontend>]) : integer + Returns an integer value corresponding to the sessions creation rate on the + frontend, in number of new sessions per second. This is used with ACLs to + limit the incoming session rate to an acceptable range in order to prevent + abuse of service at the earliest moment, for example when combined with other + layer 4 ACLs in order to force the clients to wait a bit for the rate to go + down below the limit. It can also be useful to add this element to logs using + a log-format directive. See also the "rate-limit sessions" directive for use + in frontends. + + Example : + # This frontend limits incoming mails to 10/s with a max of 100 + # concurrent connections. We accept any connection below 10/s, and + # force excess clients to wait for 100 ms. Since clients are limited to + # 100 max, there cannot be more than 10 incoming mails per second. + frontend mail + bind :25 + mode tcp + maxconn 100 + acl too_fast fe_sess_rate ge 10 + tcp-request inspect-delay 100ms + tcp-request content accept if ! too_fast + tcp-request content accept if WAIT_END + +hostname : string + Returns the system hostname. + +int(<integer>) : signed integer + Returns a signed integer. + +ipv4(<ipv4>) : ipv4 + Returns an ipv4. + +ipv6(<ipv6>) : ipv6 + Returns an ipv6. + +last_rule_file : string + This returns the name of the configuration file containing the last final + rule that was matched during stream analysis. A final rule is one that + terminates the evaluation of the rule set (like an "accept", "deny" or + "redirect"). This works for TCP request and response rules acting on the + "content" rulesets, and on HTTP rules from "http-request", "http-response" + and "http-after-response" rule sets. The legacy "redirect" rulesets are not + supported (such information is not stored there), and neither "tcp-request + connection" nor "tcp-request session" rulesets are supported because the + information is stored at the stream level and streams do not exist during + these rules. The main purpose of this function is to be able to report in + logs where was the rule that gave the final verdict, in order to help + figure why a request was denied for example. See also "last_rule_line". + +last_rule_line : integer + This returns the line number in the configuration file where is located the + last final rule that was matched during stream analysis. A final rule is one + that terminates the evaluation of the rule set (like an "accept", "deny" or + "redirect"). This works for TCP request and response rules acting on the + "content" rulesets, and on HTTP rules from "http-request", "http-response" + and "http-after-response" rule sets. The legacy "redirect" rulesets are not + supported (such information is not stored there), and neither "tcp-request + connection" nor "tcp-request session" rulesets are supported because the + information is stored at the stream level and streams do not exist during + these rules. The main purpose of this function is to be able to report in + logs where was the rule that gave the final verdict, in order to help + figure why a request was denied for example. See also "last_rule_file". + +lat_ns_avg : integer + Returns the average number of nanoseconds spent between the moment the task + handling the stream is woken up and the moment it is effectively called. This + number is reset for each new request on the same connections in case of HTTP + keep-alive. This value indicates the overall latency inflicted to the current + request by all other requests being processed in parallel, and is a direct + indicator of perceived performance due to noisy neighbours. In order to keep + the value low, it is possible to reduce the scheduler's run queue depth using + "tune.runqueue-depth", to reduce the number of concurrent events processed at + once using "tune.maxpollevents", to decrease the stream's nice value using + the "nice" option on the "bind" lines or in the frontend, to enable low + latency scheduling using "tune.sched.low-latency", or to look for other heavy + requests in logs (those exhibiting large values of "cpu_ns_avg"), whose + processing needs to be adjusted or fixed. Compression of large buffers could + be a culprit, like heavy regex or long lists of regex. Note: this value is + exactly lat_ns_tot divided by cpu_calls. + +lat_ns_tot : integer + Returns the total number of nanoseconds spent between the moment the task + handling the stream is woken up and the moment it is effectively called. This + number is reset for each new request on the same connections in case of HTTP + keep-alive. This value indicates the overall latency inflicted to the current + request by all other requests being processed in parallel, and is a direct + indicator of perceived performance due to noisy neighbours. In order to keep + the value low, it is possible to reduce the scheduler's run queue depth using + "tune.runqueue-depth", to reduce the number of concurrent events processed at + once using "tune.maxpollevents", to decrease the stream's nice value using + the "nice" option on the "bind" lines or in the frontend, to enable low + latency scheduling using "tune.sched.low-latency", or to look for other heavy + requests in logs (those exhibiting large values of "cpu_ns_avg"), whose + processing needs to be adjusted or fixed. Compression of large buffers could + be a culprit, like heavy regex or long lists of regex. Note: while it + may intuitively seem that the total latency adds to a transfer time, it is + almost never true because while a task waits for the CPU, network buffers + continue to fill up and the next call will process more at once. The value + may be artificially high due to a high cpu_calls count, for example when + processing many HTTP chunks, and for this reason it is often preferred to log + lat_ns_avg instead, which is a more relevant performance indicator. + +meth(<method>) : method + Returns a method. + +nbsrv([<backend>]) : integer + Returns an integer value corresponding to the number of usable servers of + either the current backend or the named backend. This is mostly used with + ACLs but can also be useful when added to logs. This is normally used to + switch to an alternate backend when the number of servers is too low to + to handle some load. It is useful to report a failure when combined with + "monitor fail". + +prio_class : integer + Returns the priority class of the current session for http mode or connection + for tcp mode. The value will be that set by the last call to "http-request + set-priority-class" or "tcp-request content set-priority-class". + +prio_offset : integer + Returns the priority offset of the current session for http mode or + connection for tcp mode. The value will be that set by the last call to + "http-request set-priority-offset" or "tcp-request content + set-priority-offset". + +proc : integer + Always returns value 1 (historically it would return the calling process + number). + +queue([<backend>]) : integer + Returns the total number of queued connections of the designated backend, + including all the connections in server queues. If no backend name is + specified, the current one is used, but it is also possible to check another + one. This is useful with ACLs or to pass statistics to backend servers. This + can be used to take actions when queuing goes above a known level, generally + indicating a surge of traffic or a massive slowdown on the servers. One + possible action could be to reject new users but still accept old ones. See + also the "avg_queue", "be_conn", and "be_sess_rate" fetches. + +rand([<range>]) : integer + Returns a random integer value within a range of <range> possible values, + starting at zero. If the range is not specified, it defaults to 2^32, which + gives numbers between 0 and 4294967295. It can be useful to pass some values + needed to take some routing decisions for example, or just for debugging + purposes. This random must not be used for security purposes. + +srv_conn([<backend>/]<server>) : integer + Returns an integer value corresponding to the number of currently established + connections on the designated server, possibly including the connection being + evaluated. If <backend> is omitted, then the server is looked up in the + current backend. It can be used to use a specific farm when one server is + full, or to inform the server about our view of the number of active + connections with it. See also the "fe_conn", "be_conn", "queue", and + "srv_conn_free" fetch methods. + +srv_conn_free([<backend>/]<server>) : integer + Returns an integer value corresponding to the number of available connections + on the designated server, possibly including the connection being evaluated. + The value does not include queue slots. If <backend> is omitted, then the + server is looked up in the current backend. It can be used to use a specific + farm when one server is full, or to inform the server about our view of the + number of active connections with it. See also the "be_conn_free" and + "srv_conn" fetch methods. + + OTHER CAVEATS AND NOTES: If the server maxconn is 0, then this fetch clearly + does not make sense, in which case the value returned will be -1. + +srv_is_up([<backend>/]<server>) : boolean + Returns true when the designated server is UP, and false when it is either + DOWN or in maintenance mode. If <backend> is omitted, then the server is + looked up in the current backend. It is mainly used to take action based on + an external status reported via a health check (e.g. a geographical site's + availability). Another possible use which is more of a hack consists in + using dummy servers as boolean variables that can be enabled or disabled from + the CLI, so that rules depending on those ACLs can be tweaked in realtime. + +srv_queue([<backend>/]<server>) : integer + Returns an integer value corresponding to the number of connections currently + pending in the designated server's queue. If <backend> is omitted, then the + server is looked up in the current backend. It can sometimes be used together + with the "use-server" directive to force to use a known faster server when it + is not much loaded. See also the "srv_conn", "avg_queue" and "queue" sample + fetch methods. + +srv_sess_rate([<backend>/]<server>) : integer + Returns an integer corresponding to the sessions creation rate on the + designated server, in number of new sessions per second. If <backend> is + omitted, then the server is looked up in the current backend. This is mostly + used with ACLs but can make sense with logs too. This is used to switch to an + alternate backend when an expensive or fragile one reaches too high a session + rate, or to limit abuse of service (e.g. prevent latent requests from + overloading servers). + + Example : + # Redirect to a separate back + acl srv1_full srv_sess_rate(be1/srv1) gt 50 + acl srv2_full srv_sess_rate(be1/srv2) gt 50 + use_backend be2 if srv1_full or srv2_full + +srv_iweight([<backend>/]<server>) : integer + Returns an integer corresponding to the server's initial weight. If <backend> + is omitted, then the server is looked up in the current backend. See also + "srv_weight" and "srv_uweight". + +srv_uweight([<backend>/]<server>) : integer + Returns an integer corresponding to the user visible server's weight. If + <backend> is omitted, then the server is looked up in the current + backend. See also "srv_weight" and "srv_iweight". + +srv_weight([<backend>/]<server>) : integer + Returns an integer corresponding to the current (or effective) server's + weight. If <backend> is omitted, then the server is looked up in the current + backend. See also "srv_iweight" and "srv_uweight". + +stopping : boolean + Returns TRUE if the process calling the function is currently stopping. This + can be useful for logging, or for relaxing certain checks or helping close + certain connections upon graceful shutdown. + +str(<string>) : string + Returns a string. + +table_avl([<table>]) : integer + Returns the total number of available entries in the current proxy's + stick-table or in the designated stick-table. See also table_cnt. + +table_cnt([<table>]) : integer + Returns the total number of entries currently in use in the current proxy's + stick-table or in the designated stick-table. See also src_conn_cnt and + table_avl for other entry counting methods. + +thread : integer + Returns an integer value corresponding to the position of the thread calling + the function, between 0 and (global.nbthread-1). This is useful for logging + and debugging purposes. + +uuid([<version>]) : string + Returns a UUID following the RFC4122 standard. If the version is not + specified, a UUID version 4 (fully random) is returned. + Currently, only version 4 is supported. + +var(<var-name>[,<default>]) : undefined + Returns a variable with the stored type. If the variable is not set, the + sample fetch fails, unless a default value is provided, in which case it will + return it as a string. Empty strings are permitted. The name of the variable + starts with an indication about its scope. The scopes allowed are: + "proc" : the variable is shared with the whole process + "sess" : the variable is shared with the whole session + "txn" : the variable is shared with the transaction (request and + response), + "req" : the variable is shared only during request processing, + "res" : the variable is shared only during response processing. + This prefix is followed by a name. The separator is a '.'. The name may only + contain characters 'a-z', 'A-Z', '0-9', '.' and '_'. + +7.3.3. Fetching samples at Layer 4 +---------------------------------- + +The layer 4 usually describes just the transport layer which in HAProxy is +closest to the connection, where no content is yet made available. The fetch +methods described here are usable as low as the "tcp-request connection" rule +sets unless they require some future information. Those generally include +TCP/IP addresses and ports, as well as elements from stick-tables related to +the incoming connection. For retrieving a value from a sticky counters, the +counter number can be explicitly set as 0, 1, or 2 using the pre-defined +"sc0_", "sc1_", or "sc2_" prefix. These three pre-defined prefixes can only be +used if MAX_SESS_STKCTR value does not exceed 3, otherwise the counter number +can be specified as the first integer argument when using the "sc_" prefix. +Starting from "sc_0" to "sc_N" where N is (MAX_SESS_STKCTR-1). An optional +table may be specified with the "sc*" form, in which case the currently +tracked key will be looked up into this alternate table instead of the table +currently being tracked. + +bc_dst : ip + This is the destination ip address of the connection on the server side, + which is the server address HAProxy connected to. It is of type IP and works + on both IPv4 and IPv6 tables. On IPv6 tables, IPv4 address is mapped to its + IPv6 equivalent, according to RFC 4291. + +bc_dst_port : integer + Returns an integer value corresponding to the destination TCP port of the + connection on the server side, which is the port HAProxy connected to. + +bc_err : integer + Returns the ID of the error that might have occurred on the current backend + connection. See the "fc_err_str" fetch for a full list of error codes + and their corresponding error message. + +bc_err_str : string + Returns an error message describing what problem happened on the current + backend connection, resulting in a connection failure. See the + "fc_err_str" fetch for a full list of error codes and their + corresponding error message. + +bc_http_major : integer + Returns the backend connection's HTTP major version encoding, which may be 1 + for HTTP/0.9 to HTTP/1.1 or 2 for HTTP/2. Note, this is based on the on-wire + encoding and not the version present in the request header. + +bc_src : ip + This is the source ip address of the connection on the server side, which is + the server address HAProxy connected from. It is of type IP and works on both + IPv4 and IPv6 tables. On IPv6 tables, IPv4 addresses are mapped to their IPv6 + equivalent, according to RFC 4291. + +bc_src_port : integer + Returns an integer value corresponding to the TCP source port of the + connection on the server side, which is the port HAProxy connected from. + +be_id : integer + Returns an integer containing the current backend's id. It can be used in + frontends with responses to check which backend processed the request. It can + also be used in a tcp-check or an http-check ruleset. + +be_name : string + Returns a string containing the current backend's name. It can be used in + frontends with responses to check which backend processed the request. It can + also be used in a tcp-check or an http-check ruleset. + +be_server_timeout : integer + Returns the configuration value in millisecond for the server timeout of the + current backend. This timeout can be overwritten by a "set-timeout" rule. See + also the "cur_server_timeout". + +be_tunnel_timeout : integer + Returns the configuration value in millisecond for the tunnel timeout of the + current backend. This timeout can be overwritten by a "set-timeout" rule. See + also the "cur_tunnel_timeout". + +cur_server_timeout : integer + Returns the currently applied server timeout in millisecond for the stream. + In the default case, this will be equal to be_server_timeout unless a + "set-timeout" rule has been applied. See also "be_server_timeout". + +cur_tunnel_timeout : integer + Returns the currently applied tunnel timeout in millisecond for the stream. + In the default case, this will be equal to be_tunnel_timeout unless a + "set-timeout" rule has been applied. See also "be_tunnel_timeout". + +dst : ip + This is the destination IP address of the connection on the client side, + which is the address the client connected to. Any tcp/http rules may alter + this address. It can be useful when running in transparent mode. It is of + type IP and works on both IPv4 and IPv6 tables. On IPv6 tables, IPv4 address + is mapped to its IPv6 equivalent, according to RFC 4291. When the incoming + connection passed through address translation or redirection involving + connection tracking, the original destination address before the redirection + will be reported. On Linux systems, the source and destination may seldom + appear reversed if the nf_conntrack_tcp_loose sysctl is set, because a late + response may reopen a timed out connection and switch what is believed to be + the source and the destination. + +dst_conn : integer + Returns an integer value corresponding to the number of currently established + connections on the same socket including the one being evaluated. It is + normally used with ACLs but can as well be used to pass the information to + servers in an HTTP header or in logs. It can be used to either return a sorry + page before hard-blocking, or to use a specific backend to drain new requests + when the socket is considered saturated. This offers the ability to assign + different limits to different listening ports or addresses. See also the + "fe_conn" and "be_conn" fetches. + +dst_is_local : boolean + Returns true if the destination address of the incoming connection is local + to the system, or false if the address doesn't exist on the system, meaning + that it was intercepted in transparent mode. It can be useful to apply + certain rules by default to forwarded traffic and other rules to the traffic + targeting the real address of the machine. For example the stats page could + be delivered only on this address, or SSH access could be locally redirected. + Please note that the check involves a few system calls, so it's better to do + it only once per connection. + +dst_port : integer + Returns an integer value corresponding to the destination TCP port of the + connection on the client side, which is the port the client connected to. + Any tcp/http rules may alter this address. This might be used when running in + transparent mode, when assigning dynamic ports to some clients for a whole + application session, to stick all users to a same server, or to pass the + destination port information to a server using an HTTP header. + +fc_dst : ip + This is the original destination IP address of the connection on the client + side. Only "tcp-request connection" rules may alter this address. See "dst" + for details. + +fc_dst_is_local : boolean + Returns true if the original destination address of the incoming connection + is local to the system, or false if the address doesn't exist on the + system. See "dst_is_local" for details. + +fc_dst_port : integer + Returns an integer value corresponding to the original destination TCP port + of the connection on the client side. Only "tcp-request connection" rules may + alter this address. See "dst-port" for details. + +fc_err : integer + Returns the ID of the error that might have occurred on the current + connection. Any strictly positive value of this fetch indicates that the + connection did not succeed and would result in an error log being output (as + described in section 8.2.6). See the "fc_err_str" fetch for a full list of + error codes and their corresponding error message. + +fc_err_str : string + Returns an error message describing what problem happened on the current + connection, resulting in a connection failure. This string corresponds to the + "message" part of the error log format (see section 8.2.6). See below for a + full list of error codes and their corresponding error messages : + + +----+---------------------------------------------------------------------------+ + | ID | message | + +----+---------------------------------------------------------------------------+ + | 0 | "Success" | + | 1 | "Reached configured maxconn value" | + | 2 | "Too many sockets on the process" | + | 3 | "Too many sockets on the system" | + | 4 | "Out of system buffers" | + | 5 | "Protocol or address family not supported" | + | 6 | "General socket error" | + | 7 | "Source port range exhausted" | + | 8 | "Can't bind to source address" | + | 9 | "Out of local source ports on the system" | + | 10 | "Local source address already in use" | + | 11 | "Connection closed while waiting for PROXY protocol header" | + | 12 | "Connection error while waiting for PROXY protocol header" | + | 13 | "Timeout while waiting for PROXY protocol header" | + | 14 | "Truncated PROXY protocol header received" | + | 15 | "Received something which does not look like a PROXY protocol header" | + | 16 | "Received an invalid PROXY protocol header" | + | 17 | "Received an unhandled protocol in the PROXY protocol header" | + | 18 | "Connection closed while waiting for NetScaler Client IP header" | + | 19 | "Connection error while waiting for NetScaler Client IP header" | + | 20 | "Timeout while waiting for a NetScaler Client IP header" | + | 21 | "Truncated NetScaler Client IP header received" | + | 22 | "Received an invalid NetScaler Client IP magic number" | + | 23 | "Received an unhandled protocol in the NetScaler Client IP header" | + | 24 | "Connection closed during SSL handshake" | + | 25 | "Connection error during SSL handshake" | + | 26 | "Timeout during SSL handshake" | + | 27 | "Too many SSL connections" | + | 28 | "Out of memory when initializing an SSL connection" | + | 29 | "Rejected a client-initiated SSL renegotiation attempt" | + | 30 | "SSL client CA chain cannot be verified" | + | 31 | "SSL client certificate not trusted" | + | 32 | "Server presented an SSL certificate different from the configured one" | + | 33 | "Server presented an SSL certificate different from the expected one" | + | 34 | "SSL handshake failure" | + | 35 | "SSL handshake failure after heartbeat" | + | 36 | "Stopped a TLSv1 heartbeat attack (CVE-2014-0160)" | + | 37 | "Attempt to use SSL on an unknown target (internal error)" | + | 38 | "Server refused early data" | + | 39 | "SOCKS4 Proxy write error during handshake" | + | 40 | "SOCKS4 Proxy read error during handshake" | + | 41 | "SOCKS4 Proxy deny the request" | + | 42 | "SOCKS4 Proxy handshake aborted by server" | + | 43 | "SSL fatal error" | + +----+---------------------------------------------------------------------------+ + +fc_fackets : integer + Returns the fack counter measured by the kernel for the client + connection. If the server connection is not established, if the connection is + not TCP or if the operating system does not support TCP_INFO, for example + Linux kernels before 2.4, the sample fetch fails. + +fc_http_major : integer + Reports the front connection's HTTP major version encoding, which may be 1 + for HTTP/0.9 to HTTP/1.1 or 2 for HTTP/2. Note, this is based on the on-wire + encoding and not on the version present in the request header. + +fc_lost : integer + Returns the lost counter measured by the kernel for the client + connection. If the server connection is not established, if the connection is + not TCP or if the operating system does not support TCP_INFO, for example + Linux kernels before 2.4, the sample fetch fails. + +fc_pp_authority : string + Returns the authority TLV sent by the client in the PROXY protocol header, + if any. + +fc_pp_unique_id : string + Returns the unique ID TLV sent by the client in the PROXY protocol header, + if any. + +fc_rcvd_proxy : boolean + Returns true if the client initiated the connection with a PROXY protocol + header. + +fc_reordering : integer + Returns the reordering counter measured by the kernel for the client + connection. If the server connection is not established, if the connection is + not TCP or if the operating system does not support TCP_INFO, for example + Linux kernels before 2.4, the sample fetch fails. + +fc_retrans : integer + Returns the retransmits counter measured by the kernel for the client + connection. If the server connection is not established, if the connection is + not TCP or if the operating system does not support TCP_INFO, for example + Linux kernels before 2.4, the sample fetch fails. + +fc_rtt(<unit>) : integer + Returns the Round Trip Time (RTT) measured by the kernel for the client + connection. <unit> is facultative, by default the unit is milliseconds. <unit> + can be set to "ms" for milliseconds or "us" for microseconds. If the server + connection is not established, if the connection is not TCP or if the + operating system does not support TCP_INFO, for example Linux kernels before + 2.4, the sample fetch fails. + +fc_rttvar(<unit>) : integer + Returns the Round Trip Time (RTT) variance measured by the kernel for the + client connection. <unit> is facultative, by default the unit is milliseconds. + <unit> can be set to "ms" for milliseconds or "us" for microseconds. If the + server connection is not established, if the connection is not TCP or if the + operating system does not support TCP_INFO, for example Linux kernels before + 2.4, the sample fetch fails. + +fc_sacked : integer + Returns the sacked counter measured by the kernel for the client connection. + If the server connection is not established, if the connection is not TCP or + if the operating system does not support TCP_INFO, for example Linux kernels + before 2.4, the sample fetch fails. + +fc_src : ip + This is the original destination IP address of the connection on the client + side. Only "tcp-request connection" rules may alter this address. See "src" + for details. + +fc_src_is_local : boolean + Returns true if the source address of incoming connection is local to the + system, or false if the address doesn't exist on the system. See + "src_is_local" for details. + +fc_src_port : integer + + Returns an integer value corresponding to the TCP source port of the + connection on the client side. Only "tcp-request connection" rules may alter + this address. See "src-port" for details. + + +fc_unacked : integer + Returns the unacked counter measured by the kernel for the client connection. + If the server connection is not established, if the connection is not TCP or + if the operating system does not support TCP_INFO, for example Linux kernels + before 2.4, the sample fetch fails. + +fe_defbe : string + Returns a string containing the frontend's default backend name. It can be + used in frontends to check which backend will handle requests by default. + +fe_id : integer + Returns an integer containing the current frontend's id. It can be used in + backends to check from which frontend it was called, or to stick all users + coming via a same frontend to the same server. + +fe_name : string + Returns a string containing the current frontend's name. It can be used in + backends to check from which frontend it was called, or to stick all users + coming via a same frontend to the same server. + +fe_client_timeout : integer + Returns the configuration value in millisecond for the client timeout of the + current frontend. + +sc_bytes_in_rate(<ctr>[,<table>]) : integer +sc0_bytes_in_rate([<table>]) : integer +sc1_bytes_in_rate([<table>]) : integer +sc2_bytes_in_rate([<table>]) : integer + Returns the average client-to-server bytes rate from the currently tracked + counters, measured in amount of bytes over the period configured in the + table. See also src_bytes_in_rate. + +sc_bytes_out_rate(<ctr>[,<table>]) : integer +sc0_bytes_out_rate([<table>]) : integer +sc1_bytes_out_rate([<table>]) : integer +sc2_bytes_out_rate([<table>]) : integer + Returns the average server-to-client bytes rate from the currently tracked + counters, measured in amount of bytes over the period configured in the + table. See also src_bytes_out_rate. + +sc_clr_gpc(<idx>,<ctr>[,<table>]) : integer + Clears the General Purpose Counter at the index <idx> of the array + associated to the designated tracked counter of ID <ctr> from current + proxy's stick table or from the designated stick-table <table>, and + returns its previous value. <idx> is an integer between 0 and 99 and + <ctr> an integer between 0 and 2. + Before the first invocation, the stored value is zero, so first invocation + will always return zero. + This fetch applies only to the 'gpc' array data_type (and not to the legacy + 'gpc0' nor 'gpc1' data_types). + +sc_clr_gpc0(<ctr>[,<table>]) : integer +sc0_clr_gpc0([<table>]) : integer +sc1_clr_gpc0([<table>]) : integer +sc2_clr_gpc0([<table>]) : integer + Clears the first General Purpose Counter associated to the currently tracked + counters, and returns its previous value. Before the first invocation, the + stored value is zero, so first invocation will always return zero. This is + typically used as a second ACL in an expression in order to mark a connection + when a first ACL was verified : + + Example: + # block if 5 consecutive requests continue to come faster than 10 sess + # per second, and reset the counter as soon as the traffic slows down. + acl abuse sc0_http_req_rate gt 10 + acl kill sc0_inc_gpc0 gt 5 + acl save sc0_clr_gpc0 ge 0 + tcp-request connection accept if !abuse save + tcp-request connection reject if abuse kill + +sc_clr_gpc1(<ctr>[,<table>]) : integer +sc0_clr_gpc1([<table>]) : integer +sc1_clr_gpc1([<table>]) : integer +sc2_clr_gpc1([<table>]) : integer + Clears the second General Purpose Counter associated to the currently tracked + counters, and returns its previous value. Before the first invocation, the + stored value is zero, so first invocation will always return zero. This is + typically used as a second ACL in an expression in order to mark a connection + when a first ACL was verified. + +sc_conn_cnt(<ctr>[,<table>]) : integer +sc0_conn_cnt([<table>]) : integer +sc1_conn_cnt([<table>]) : integer +sc2_conn_cnt([<table>]) : integer + Returns the cumulative number of incoming connections from currently tracked + counters. See also src_conn_cnt. + +sc_conn_cur(<ctr>[,<table>]) : integer +sc0_conn_cur([<table>]) : integer +sc1_conn_cur([<table>]) : integer +sc2_conn_cur([<table>]) : integer + Returns the current amount of concurrent connections tracking the same + tracked counters. This number is automatically incremented when tracking + begins and decremented when tracking stops. See also src_conn_cur. + +sc_conn_rate(<ctr>[,<table>]) : integer +sc0_conn_rate([<table>]) : integer +sc1_conn_rate([<table>]) : integer +sc2_conn_rate([<table>]) : integer + Returns the average connection rate from the currently tracked counters, + measured in amount of connections over the period configured in the table. + See also src_conn_rate. + +sc_get_gpc(<idx>,<ctr>[,<table>]) : integer + Returns the value of the General Purpose Counter at the index <idx> + in the GPC array and associated to the currently tracked counter of + ID <ctr> from the current proxy's stick-table or from the designated + stick-table <table>. <idx> is an integer between 0 and 99 and + <ctr> an integer between 0 and 2. If there is not gpc stored at this + index, zero is returned. + This fetch applies only to the 'gpc' array data_type (and not to the legacy + 'gpc0' nor 'gpc1' data_types). See also src_get_gpc and sc_inc_gpc. + +sc_get_gpc0(<ctr>[,<table>]) : integer +sc0_get_gpc0([<table>]) : integer +sc1_get_gpc0([<table>]) : integer +sc2_get_gpc0([<table>]) : integer + Returns the value of the first General Purpose Counter associated to the + currently tracked counters. See also src_get_gpc0 and sc/sc0/sc1/sc2_inc_gpc0. + +sc_get_gpc1(<ctr>[,<table>]) : integer +sc0_get_gpc1([<table>]) : integer +sc1_get_gpc1([<table>]) : integer +sc2_get_gpc1([<table>]) : integer + Returns the value of the second General Purpose Counter associated to the + currently tracked counters. See also src_get_gpc1 and sc/sc0/sc1/sc2_inc_gpc1. + +sc_get_gpt(<idx>,<ctr>[,<table>]) : integer + Returns the value of the first General Purpose Tag at the index <idx> of + the array associated to the tracked counter of ID <ctr> and from the + current proxy's sitck-table or the designated stick-table <table>. <idx> + is an integer between 0 and 99 and <ctr> an integer between 0 and 2. + If there is no GPT stored at this index, zero is returned. + This fetch applies only to the 'gpt' array data_type (and not on + the legacy 'gpt0' data-type). See also src_get_gpt. + +sc_get_gpt0(<ctr>[,<table>]) : integer +sc0_get_gpt0([<table>]) : integer +sc1_get_gpt0([<table>]) : integer +sc2_get_gpt0([<table>]) : integer + Returns the value of the first General Purpose Tag associated to the + currently tracked counters. See also src_get_gpt0. + +sc_gpc_rate(<idx>,<ctr>[,<table>]) : integer + Returns the average increment rate of the General Purpose Counter at the + index <idx> of the array associated to the tracked counter of ID <ctr> from + the current proxy's table or from the designated stick-table <table>. + It reports the frequency which the gpc counter was incremented over the + configured period. <idx> is an integer between 0 and 99 and <ctr> an integer + between 0 and 2. + Note that the 'gpc_rate' counter array must be stored in the stick-table + for a value to be returned, as 'gpc' only holds the event count. + This fetch applies only to the 'gpc_rate' array data_type (and not to + the legacy 'gpc0_rate' nor 'gpc1_rate' data_types). + See also src_gpc_rate, sc_get_gpc, and sc_inc_gpc. + +sc_gpc0_rate(<ctr>[,<table>]) : integer +sc0_gpc0_rate([<table>]) : integer +sc1_gpc0_rate([<table>]) : integer +sc2_gpc0_rate([<table>]) : integer + Returns the average increment rate of the first General Purpose Counter + associated to the currently tracked counters. It reports the frequency + which the gpc0 counter was incremented over the configured period. See also + src_gpc0_rate, sc/sc0/sc1/sc2_get_gpc0, and sc/sc0/sc1/sc2_inc_gpc0. Note + that the "gpc0_rate" counter must be stored in the stick-table for a value to + be returned, as "gpc0" only holds the event count. + +sc_gpc1_rate(<ctr>[,<table>]) : integer +sc0_gpc1_rate([<table>]) : integer +sc1_gpc1_rate([<table>]) : integer +sc2_gpc1_rate([<table>]) : integer + Returns the average increment rate of the second General Purpose Counter + associated to the currently tracked counters. It reports the frequency + which the gpc1 counter was incremented over the configured period. See also + src_gpcA_rate, sc/sc0/sc1/sc2_get_gpc1, and sc/sc0/sc1/sc2_inc_gpc1. Note + that the "gpc1_rate" counter must be stored in the stick-table for a value to + be returned, as "gpc1" only holds the event count. + +sc_http_err_cnt(<ctr>[,<table>]) : integer +sc0_http_err_cnt([<table>]) : integer +sc1_http_err_cnt([<table>]) : integer +sc2_http_err_cnt([<table>]) : integer + Returns the cumulative number of HTTP errors from the currently tracked + counters. This includes the both request errors and 4xx error responses. + See also src_http_err_cnt. + +sc_http_err_rate(<ctr>[,<table>]) : integer +sc0_http_err_rate([<table>]) : integer +sc1_http_err_rate([<table>]) : integer +sc2_http_err_rate([<table>]) : integer + Returns the average rate of HTTP errors from the currently tracked counters, + measured in amount of errors over the period configured in the table. This + includes the both request errors and 4xx error responses. See also + src_http_err_rate. + +sc_http_fail_cnt(<ctr>[,<table>]) : integer +sc0_http_fail_cnt([<table>]) : integer +sc1_http_fail_cnt([<table>]) : integer +sc2_http_fail_cnt([<table>]) : integer + Returns the cumulative number of HTTP response failures from the currently + tracked counters. This includes the both response errors and 5xx status codes + other than 501 and 505. See also src_http_fail_cnt. + +sc_http_fail_rate(<ctr>[,<table>]) : integer +sc0_http_fail_rate([<table>]) : integer +sc1_http_fail_rate([<table>]) : integer +sc2_http_fail_rate([<table>]) : integer + Returns the average rate of HTTP response failures from the currently tracked + counters, measured in amount of failures over the period configured in the + table. This includes the both response errors and 5xx status codes other than + 501 and 505. See also src_http_fail_rate. + +sc_http_req_cnt(<ctr>[,<table>]) : integer +sc0_http_req_cnt([<table>]) : integer +sc1_http_req_cnt([<table>]) : integer +sc2_http_req_cnt([<table>]) : integer + Returns the cumulative number of HTTP requests from the currently tracked + counters. This includes every started request, valid or not. See also + src_http_req_cnt. + +sc_http_req_rate(<ctr>[,<table>]) : integer +sc0_http_req_rate([<table>]) : integer +sc1_http_req_rate([<table>]) : integer +sc2_http_req_rate([<table>]) : integer + Returns the average rate of HTTP requests from the currently tracked + counters, measured in amount of requests over the period configured in + the table. This includes every started request, valid or not. See also + src_http_req_rate. + +sc_inc_gpc(<idx>,<ctr>[,<table>]) : integer + Increments the General Purpose Counter at the index <idx> of the array + associated to the designated tracked counter of ID <ctr> from current + proxy's stick table or from the designated stick-table <table>, and + returns its new value. <idx> is an integer between 0 and 99 and + <ctr> an integer between 0 and 2. + Before the first invocation, the stored value is zero, so first invocation + will increase it to 1 and will return 1. + This fetch applies only to the 'gpc' array data_type (and not to the legacy + 'gpc0' nor 'gpc1' data_types). + +sc_inc_gpc0(<ctr>[,<table>]) : integer +sc0_inc_gpc0([<table>]) : integer +sc1_inc_gpc0([<table>]) : integer +sc2_inc_gpc0([<table>]) : integer + Increments the first General Purpose Counter associated to the currently + tracked counters, and returns its new value. Before the first invocation, + the stored value is zero, so first invocation will increase it to 1 and will + return 1. This is typically used as a second ACL in an expression in order + to mark a connection when a first ACL was verified : + + Example: + acl abuse sc0_http_req_rate gt 10 + acl kill sc0_inc_gpc0 gt 0 + tcp-request connection reject if abuse kill + +sc_inc_gpc1(<ctr>[,<table>]) : integer +sc0_inc_gpc1([<table>]) : integer +sc1_inc_gpc1([<table>]) : integer +sc2_inc_gpc1([<table>]) : integer + Increments the second General Purpose Counter associated to the currently + tracked counters, and returns its new value. Before the first invocation, + the stored value is zero, so first invocation will increase it to 1 and will + return 1. This is typically used as a second ACL in an expression in order + to mark a connection when a first ACL was verified. + +sc_kbytes_in(<ctr>[,<table>]) : integer +sc0_kbytes_in([<table>]) : integer +sc1_kbytes_in([<table>]) : integer +sc2_kbytes_in([<table>]) : integer + Returns the total amount of client-to-server data from the currently tracked + counters, measured in kilobytes. The test is currently performed on 32-bit + integers, which limits values to 4 terabytes. See also src_kbytes_in. + +sc_kbytes_out(<ctr>[,<table>]) : integer +sc0_kbytes_out([<table>]) : integer +sc1_kbytes_out([<table>]) : integer +sc2_kbytes_out([<table>]) : integer + Returns the total amount of server-to-client data from the currently tracked + counters, measured in kilobytes. The test is currently performed on 32-bit + integers, which limits values to 4 terabytes. See also src_kbytes_out. + +sc_sess_cnt(<ctr>[,<table>]) : integer +sc0_sess_cnt([<table>]) : integer +sc1_sess_cnt([<table>]) : integer +sc2_sess_cnt([<table>]) : integer + Returns the cumulative number of incoming connections that were transformed + into sessions, which means that they were accepted by a "tcp-request + connection" rule, from the currently tracked counters. A backend may count + more sessions than connections because each connection could result in many + backend sessions if some HTTP keep-alive is performed over the connection + with the client. See also src_sess_cnt. + +sc_sess_rate(<ctr>[,<table>]) : integer +sc0_sess_rate([<table>]) : integer +sc1_sess_rate([<table>]) : integer +sc2_sess_rate([<table>]) : integer + Returns the average session rate from the currently tracked counters, + measured in amount of sessions over the period configured in the table. A + session is a connection that got past the early "tcp-request connection" + rules. A backend may count more sessions than connections because each + connection could result in many backend sessions if some HTTP keep-alive is + performed over the connection with the client. See also src_sess_rate. + +sc_tracked(<ctr>[,<table>]) : boolean +sc0_tracked([<table>]) : boolean +sc1_tracked([<table>]) : boolean +sc2_tracked([<table>]) : boolean + Returns true if the designated session counter is currently being tracked by + the current session. This can be useful when deciding whether or not we want + to set some values in a header passed to the server. + +sc_trackers(<ctr>[,<table>]) : integer +sc0_trackers([<table>]) : integer +sc1_trackers([<table>]) : integer +sc2_trackers([<table>]) : integer + Returns the current amount of concurrent connections tracking the same + tracked counters. This number is automatically incremented when tracking + begins and decremented when tracking stops. It differs from sc0_conn_cur in + that it does not rely on any stored information but on the table's reference + count (the "use" value which is returned by "show table" on the CLI). This + may sometimes be more suited for layer7 tracking. It can be used to tell a + server how many concurrent connections there are from a given address for + example. + +so_id : integer + Returns an integer containing the current listening socket's id. It is useful + in frontends involving many "bind" lines, or to stick all users coming via a + same socket to the same server. + +so_name : string + Returns a string containing the current listening socket's name, as defined + with name on a "bind" line. It can serve the same purposes as so_id but with + strings instead of integers. + +src : ip + This is the source IP address of the client of the session. Any tcp/http + rules may alter this address. It is of type IP and works on both IPv4 and + IPv6 tables. On IPv6 tables, IPv4 addresses are mapped to their IPv6 + equivalent, according to RFC 4291. Note that it is the TCP-level source + address which is used, and not the address of a client behind a + proxy. However if the "accept-proxy" or "accept-netscaler-cip" bind directive + is used, it can be the address of a client behind another PROXY-protocol + compatible component for all rule sets except "tcp-request connection" which + sees the real address. When the incoming connection passed through address + translation or redirection involving connection tracking, the original + destination address before the redirection will be reported. On Linux + systems, the source and destination may seldom appear reversed if the + nf_conntrack_tcp_loose sysctl is set, because a late response may reopen a + timed out connection and switch what is believed to be the source and the + destination. + + Example: + # add an HTTP header in requests with the originating address' country + http-request set-header X-Country %[src,map_ip(geoip.lst)] + +src_bytes_in_rate([<table>]) : integer + Returns the average bytes rate from the incoming connection's source address + in the current proxy's stick-table or in the designated stick-table, measured + in amount of bytes over the period configured in the table. If the address is + not found, zero is returned. See also sc/sc0/sc1/sc2_bytes_in_rate. + +src_bytes_out_rate([<table>]) : integer + Returns the average bytes rate to the incoming connection's source address in + the current proxy's stick-table or in the designated stick-table, measured in + amount of bytes over the period configured in the table. If the address is + not found, zero is returned. See also sc/sc0/sc1/sc2_bytes_out_rate. + +src_clr_gpc(<idx>,[<table>]) : integer + Clears the General Purpose Counter at the index <idx> of the array + associated to the incoming connection's source address in the current proxy's + stick-table or in the designated stick-table <table>, and returns its + previous value. <idx> is an integer between 0 and 99. + If the address is not found, an entry is created and 0 is returned. + This fetch applies only to the 'gpc' array data_type (and not to the legacy + 'gpc0' nor 'gpc1' data_types). + See also sc_clr_gpc. + +src_clr_gpc0([<table>]) : integer + Clears the first General Purpose Counter associated to the incoming + connection's source address in the current proxy's stick-table or in the + designated stick-table, and returns its previous value. If the address is not + found, an entry is created and 0 is returned. This is typically used as a + second ACL in an expression in order to mark a connection when a first ACL + was verified : + + Example: + # block if 5 consecutive requests continue to come faster than 10 sess + # per second, and reset the counter as soon as the traffic slows down. + acl abuse src_http_req_rate gt 10 + acl kill src_inc_gpc0 gt 5 + acl save src_clr_gpc0 ge 0 + tcp-request connection accept if !abuse save + tcp-request connection reject if abuse kill + +src_clr_gpc1([<table>]) : integer + Clears the second General Purpose Counter associated to the incoming + connection's source address in the current proxy's stick-table or in the + designated stick-table, and returns its previous value. If the address is not + found, an entry is created and 0 is returned. This is typically used as a + second ACL in an expression in order to mark a connection when a first ACL + was verified. + +src_conn_cnt([<table>]) : integer + Returns the cumulative number of connections initiated from the current + incoming connection's source address in the current proxy's stick-table or in + the designated stick-table. If the address is not found, zero is returned. + See also sc/sc0/sc1/sc2_conn_cnt. + +src_conn_cur([<table>]) : integer + Returns the current amount of concurrent connections initiated from the + current incoming connection's source address in the current proxy's + stick-table or in the designated stick-table. If the address is not found, + zero is returned. See also sc/sc0/sc1/sc2_conn_cur. + +src_conn_rate([<table>]) : integer + Returns the average connection rate from the incoming connection's source + address in the current proxy's stick-table or in the designated stick-table, + measured in amount of connections over the period configured in the table. If + the address is not found, zero is returned. See also sc/sc0/sc1/sc2_conn_rate. + +src_get_gpc(<idx>,[<table>]) : integer + Returns the value of the General Purpose Counter at the index <idx> of the + array associated to the incoming connection's source address in the + current proxy's stick-table or in the designated stick-table <table>. <idx> + is an integer between 0 and 99. + If the address is not found or there is no gpc stored at this index, zero + is returned. + This fetch applies only to the 'gpc' array data_type (and not on the legacy + 'gpc0' nor 'gpc1' data_types). + See also sc_get_gpc and src_inc_gpc. + +src_get_gpc0([<table>]) : integer + Returns the value of the first General Purpose Counter associated to the + incoming connection's source address in the current proxy's stick-table or in + the designated stick-table. If the address is not found, zero is returned. + See also sc/sc0/sc1/sc2_get_gpc0 and src_inc_gpc0. + +src_get_gpc1([<table>]) : integer + Returns the value of the second General Purpose Counter associated to the + incoming connection's source address in the current proxy's stick-table or in + the designated stick-table. If the address is not found, zero is returned. + See also sc/sc0/sc1/sc2_get_gpc1 and src_inc_gpc1. + +src_get_gpt(<idx>[,<table>]) : integer + Returns the value of the first General Purpose Tag at the index <idx> of + the array associated to the incoming connection's source address in the + current proxy's stick-table or in the designated stick-table <table>. + <idx> is an integer between 0 and 99. + If the address is not found or the GPT is not stored, zero is returned. + See also the sc_get_gpt sample fetch keyword. + +src_get_gpt0([<table>]) : integer + Returns the value of the first General Purpose Tag associated to the + incoming connection's source address in the current proxy's stick-table or in + the designated stick-table. If the address is not found, zero is returned. + See also sc/sc0/sc1/sc2_get_gpt0. + +src_gpc_rate(<idx>[,<table>]) : integer + Returns the average increment rate of the General Purpose Counter at the + index <idx> of the array associated to the incoming connection's + source address in the current proxy's stick-table or in the designated + stick-table <table>. It reports the frequency which the gpc counter was + incremented over the configured period. <idx> is an integer between 0 and 99. + Note that the 'gpc_rate' counter must be stored in the stick-table for a + value to be returned, as 'gpc' only holds the event count. + This fetch applies only to the 'gpc_rate' array data_type (and not to + the legacy 'gpc0_rate' nor 'gpc1_rate' data_types). + See also sc_gpc_rate, src_get_gpc, and sc_inc_gpc. + +src_gpc0_rate([<table>]) : integer + Returns the average increment rate of the first General Purpose Counter + associated to the incoming connection's source address in the current proxy's + stick-table or in the designated stick-table. It reports the frequency + which the gpc0 counter was incremented over the configured period. See also + sc/sc0/sc1/sc2_gpc0_rate, src_get_gpc0, and sc/sc0/sc1/sc2_inc_gpc0. Note + that the "gpc0_rate" counter must be stored in the stick-table for a value to + be returned, as "gpc0" only holds the event count. + +src_gpc1_rate([<table>]) : integer + Returns the average increment rate of the second General Purpose Counter + associated to the incoming connection's source address in the current proxy's + stick-table or in the designated stick-table. It reports the frequency + which the gpc1 counter was incremented over the configured period. See also + sc/sc0/sc1/sc2_gpc1_rate, src_get_gpc1, and sc/sc0/sc1/sc2_inc_gpc1. Note + that the "gpc1_rate" counter must be stored in the stick-table for a value to + be returned, as "gpc1" only holds the event count. + +src_http_err_cnt([<table>]) : integer + Returns the cumulative number of HTTP errors from the incoming connection's + source address in the current proxy's stick-table or in the designated + stick-table. This includes the both request errors and 4xx error responses. + See also sc/sc0/sc1/sc2_http_err_cnt. If the address is not found, zero is + returned. + +src_http_err_rate([<table>]) : integer + Returns the average rate of HTTP errors from the incoming connection's source + address in the current proxy's stick-table or in the designated stick-table, + measured in amount of errors over the period configured in the table. This + includes the both request errors and 4xx error responses. If the address is + not found, zero is returned. See also sc/sc0/sc1/sc2_http_err_rate. + +src_http_fail_cnt([<table>]) : integer + Returns the cumulative number of HTTP response failures triggered by the + incoming connection's source address in the current proxy's stick-table or in + the designated stick-table. This includes the both response errors and 5xx + status codes other than 501 and 505. See also sc/sc0/sc1/sc2_http_fail_cnt. + If the address is not found, zero is returned. + +src_http_fail_rate([<table>]) : integer + Returns the average rate of HTTP response failures triggered by the incoming + connection's source address in the current proxy's stick-table or in the + designated stick-table, measured in amount of failures over the period + configured in the table. This includes the both response errors and 5xx + status codes other than 501 and 505. If the address is not found, zero is + returned. See also sc/sc0/sc1/sc2_http_fail_rate. + +src_http_req_cnt([<table>]) : integer + Returns the cumulative number of HTTP requests from the incoming connection's + source address in the current proxy's stick-table or in the designated stick- + table. This includes every started request, valid or not. If the address is + not found, zero is returned. See also sc/sc0/sc1/sc2_http_req_cnt. + +src_http_req_rate([<table>]) : integer + Returns the average rate of HTTP requests from the incoming connection's + source address in the current proxy's stick-table or in the designated stick- + table, measured in amount of requests over the period configured in the + table. This includes every started request, valid or not. If the address is + not found, zero is returned. See also sc/sc0/sc1/sc2_http_req_rate. + +src_inc_gpc(<idx>,[<table>]) : integer + Increments the General Purpose Counter at index <idx> of the array + associated to the incoming connection's source address in the current proxy's + stick-table or in the designated stick-table <table>, and returns its new + value. <idx> is an integer between 0 and 99. + If the address is not found, an entry is created and 1 is returned. + This fetch applies only to the 'gpc' array data_type (and not to the legacy + 'gpc0' nor 'gpc1' data_types). + See also sc_inc_gpc. + +src_inc_gpc0([<table>]) : integer + Increments the first General Purpose Counter associated to the incoming + connection's source address in the current proxy's stick-table or in the + designated stick-table, and returns its new value. If the address is not + found, an entry is created and 1 is returned. See also sc0/sc2/sc2_inc_gpc0. + This is typically used as a second ACL in an expression in order to mark a + connection when a first ACL was verified : + + Example: + acl abuse src_http_req_rate gt 10 + acl kill src_inc_gpc0 gt 0 + tcp-request connection reject if abuse kill + +src_inc_gpc1([<table>]) : integer + Increments the second General Purpose Counter associated to the incoming + connection's source address in the current proxy's stick-table or in the + designated stick-table, and returns its new value. If the address is not + found, an entry is created and 1 is returned. See also sc0/sc2/sc2_inc_gpc1. + This is typically used as a second ACL in an expression in order to mark a + connection when a first ACL was verified. + +src_is_local : boolean + Returns true if the source address of the incoming connection is local to the + system, or false if the address doesn't exist on the system, meaning that it + comes from a remote machine. Note that UNIX addresses are considered local. + It can be useful to apply certain access restrictions based on where the + client comes from (e.g. require auth or https for remote machines). Please + note that the check involves a few system calls, so it's better to do it only + once per connection. + +src_kbytes_in([<table>]) : integer + Returns the total amount of data received from the incoming connection's + source address in the current proxy's stick-table or in the designated + stick-table, measured in kilobytes. If the address is not found, zero is + returned. The test is currently performed on 32-bit integers, which limits + values to 4 terabytes. See also sc/sc0/sc1/sc2_kbytes_in. + +src_kbytes_out([<table>]) : integer + Returns the total amount of data sent to the incoming connection's source + address in the current proxy's stick-table or in the designated stick-table, + measured in kilobytes. If the address is not found, zero is returned. The + test is currently performed on 32-bit integers, which limits values to 4 + terabytes. See also sc/sc0/sc1/sc2_kbytes_out. + +src_port : integer + Returns an integer value corresponding to the TCP source port of the + connection on the client side, which is the port the client connected + from. Any tcp/http rules may alter this address. Usage of this function is + very limited as modern protocols do not care much about source ports + nowadays. + +src_sess_cnt([<table>]) : integer + Returns the cumulative number of connections initiated from the incoming + connection's source IPv4 address in the current proxy's stick-table or in the + designated stick-table, that were transformed into sessions, which means that + they were accepted by "tcp-request" rules. If the address is not found, zero + is returned. See also sc/sc0/sc1/sc2_sess_cnt. + +src_sess_rate([<table>]) : integer + Returns the average session rate from the incoming connection's source + address in the current proxy's stick-table or in the designated stick-table, + measured in amount of sessions over the period configured in the table. A + session is a connection that went past the early "tcp-request" rules. If the + address is not found, zero is returned. See also sc/sc0/sc1/sc2_sess_rate. + +src_updt_conn_cnt([<table>]) : integer + Creates or updates the entry associated to the incoming connection's source + address in the current proxy's stick-table or in the designated stick-table. + This table must be configured to store the "conn_cnt" data type, otherwise + the match will be ignored. The current count is incremented by one, and the + expiration timer refreshed. The updated count is returned, so this match + can't return zero. This was used to reject service abusers based on their + source address. Note: it is recommended to use the more complete "track-sc*" + actions in "tcp-request" rules instead. + + Example : + # This frontend limits incoming SSH connections to 3 per 10 second for + # each source address, and rejects excess connections until a 10 second + # silence is observed. At most 20 addresses are tracked. + listen ssh + bind :22 + mode tcp + maxconn 100 + stick-table type ip size 20 expire 10s store conn_cnt + tcp-request content reject if { src_updt_conn_cnt gt 3 } + server local 127.0.0.1:22 + +srv_id : integer + Returns an integer containing the server's id when processing the response. + While it's almost only used with ACLs, it may be used for logging or + debugging. It can also be used in a tcp-check or an http-check ruleset. + +srv_name : string + Returns a string containing the server's name when processing the response. + While it's almost only used with ACLs, it may be used for logging or + debugging. It can also be used in a tcp-check or an http-check ruleset. + +7.3.4. Fetching samples at Layer 5 +---------------------------------- + +The layer 5 usually describes just the session layer which in HAProxy is +closest to the session once all the connection handshakes are finished, but +when no content is yet made available. The fetch methods described here are +usable as low as the "tcp-request content" rule sets unless they require some +future information. Those generally include the results of SSL negotiations. + +51d.all(<prop>[,<prop>*]) : string + Returns values for the properties requested as a string, where values are + separated by the delimiter specified with "51degrees-property-separator". + The device is identified using all the important HTTP headers from the + request. The function can be passed up to five property names, and if a + property name can't be found, the value "NoData" is returned. + + Example : + # Here the header "X-51D-DeviceTypeMobileTablet" is added to the request + # containing the three properties requested using all relevant headers from + # the request. + frontend http-in + bind *:8081 + default_backend servers + http-request set-header X-51D-DeviceTypeMobileTablet \ + %[51d.all(DeviceType,IsMobile,IsTablet)] + +ssl_bc : boolean + Returns true when the back connection was made via an SSL/TLS transport + layer and is locally deciphered. This means the outgoing connection was made + other a server with the "ssl" option. It can be used in a tcp-check or an + http-check ruleset. + +ssl_bc_alg_keysize : integer + Returns the symmetric cipher key size supported in bits when the outgoing + connection was made over an SSL/TLS transport layer. It can be used in a + tcp-check or an http-check ruleset. + +ssl_bc_alpn : string + This extracts the Application Layer Protocol Negotiation field from an + outgoing connection made via a TLS transport layer. + The result is a string containing the protocol name negotiated with the + server. The SSL library must have been built with support for TLS + extensions enabled (check haproxy -vv). Note that the TLS ALPN extension is + not advertised unless the "alpn" keyword on the "server" line specifies a + protocol list. Also, nothing forces the server to pick a protocol from this + list, any other one may be requested. The TLS ALPN extension is meant to + replace the TLS NPN extension. See also "ssl_bc_npn". It can be used in a + tcp-check or an http-check ruleset. + +ssl_bc_cipher : string + Returns the name of the used cipher when the outgoing connection was made + over an SSL/TLS transport layer. It can be used in a tcp-check or an + http-check ruleset. + +ssl_bc_client_random : binary + Returns the client random of the back connection when the incoming connection + was made over an SSL/TLS transport layer. It is useful to to decrypt traffic + sent using ephemeral ciphers. This requires OpenSSL >= 1.1.0, or BoringSSL. + It can be used in a tcp-check or an http-check ruleset. + +ssl_bc_err : integer + When the outgoing connection was made over an SSL/TLS transport layer, + returns the ID of the last error of the first error stack raised on the + backend side. It can raise handshake errors as well as other read or write + errors occurring during the connection's lifetime. In order to get a text + description of this error code, you can either use the "ssl_bc_err_str" + sample fetch or use the "openssl errstr" command (which takes an error code + in hexadecimal representation as parameter). Please refer to your SSL + library's documentation to find the exhaustive list of error codes. + +ssl_bc_err_str : string + When the outgoing connection was made over an SSL/TLS transport layer, + returns a string representation of the last error of the first error stack + that was raised on the connection from the backend's perspective. See also + "ssl_fc_err". + +ssl_bc_is_resumed : boolean + Returns true when the back connection was made over an SSL/TLS transport + layer and the newly created SSL session was resumed using a cached + session or a TLS ticket. It can be used in a tcp-check or an http-check + ruleset. + +ssl_bc_npn : string + This extracts the Next Protocol Negotiation field from an outgoing connection + made via a TLS transport layer. The result is a string containing the + protocol name negotiated with the server . The SSL library must have been + built with support for TLS extensions enabled (check haproxy -vv). Note that + the TLS NPN extension is not advertised unless the "npn" keyword on the + "server" line specifies a protocol list. Also, nothing forces the server to + pick a protocol from this list, any other one may be used. Please note that + the TLS NPN extension was replaced with ALPN. It can be used in a tcp-check + or an http-check ruleset. + +ssl_bc_protocol : string + Returns the name of the used protocol when the outgoing connection was made + over an SSL/TLS transport layer. It can be used in a tcp-check or an + http-check ruleset. + +ssl_bc_unique_id : binary + When the outgoing connection was made over an SSL/TLS transport layer, + returns the TLS unique ID as defined in RFC5929 section 3. The unique id + can be encoded to base64 using the converter: "ssl_bc_unique_id,base64". It + can be used in a tcp-check or an http-check ruleset. + +ssl_bc_server_random : binary + Returns the server random of the back connection when the incoming connection + was made over an SSL/TLS transport layer. It is useful to to decrypt traffic + sent using ephemeral ciphers. This requires OpenSSL >= 1.1.0, or BoringSSL. + It can be used in a tcp-check or an http-check ruleset. + +ssl_bc_session_id : binary + Returns the SSL ID of the back connection when the outgoing connection was + made over an SSL/TLS transport layer. It is useful to log if we want to know + if session was reused or not. It can be used in a tcp-check or an http-check + ruleset. + +ssl_bc_session_key : binary + Returns the SSL session master key of the back connection when the outgoing + connection was made over an SSL/TLS transport layer. It is useful to decrypt + traffic sent using ephemeral ciphers. This requires OpenSSL >= 1.1.0, or + BoringSSL. It can be used in a tcp-check or an http-check ruleset. + +ssl_bc_use_keysize : integer + Returns the symmetric cipher key size used in bits when the outgoing + connection was made over an SSL/TLS transport layer. It can be used in a + tcp-check or an http-check ruleset. + +ssl_c_ca_err : integer + When the incoming connection was made over an SSL/TLS transport layer, + returns the ID of the first error detected during verification of the client + certificate at depth > 0, or 0 if no error was encountered during this + verification process. Please refer to your SSL library's documentation to + find the exhaustive list of error codes. + +ssl_c_ca_err_depth : integer + When the incoming connection was made over an SSL/TLS transport layer, + returns the depth in the CA chain of the first error detected during the + verification of the client certificate. If no error is encountered, 0 is + returned. + +ssl_c_chain_der : binary + Returns the DER formatted chain certificate presented by the client when the + incoming connection was made over an SSL/TLS transport layer. When used for + an ACL, the value(s) to match against can be passed in hexadecimal form. One + can parse the result with any lib accepting ASN.1 DER data. It currently + does not support resumed sessions. + +ssl_c_der : binary + Returns the DER formatted certificate presented by the client when the + incoming connection was made over an SSL/TLS transport layer. When used for + an ACL, the value(s) to match against can be passed in hexadecimal form. + +ssl_c_err : integer + When the incoming connection was made over an SSL/TLS transport layer, + returns the ID of the first error detected during verification at depth 0, or + 0 if no error was encountered during this verification process. Please refer + to your SSL library's documentation to find the exhaustive list of error + codes. + +ssl_c_i_dn([<entry>[,<occ>[,<format>]]]) : string + When the incoming connection was made over an SSL/TLS transport layer, + returns the full distinguished name of the issuer of the certificate + presented by the client when no <entry> is specified, or the value of the + first given entry found from the beginning of the DN. If a positive/negative + occurrence number is specified as the optional second argument, it returns + the value of the nth given entry value from the beginning/end of the DN. + For instance, "ssl_c_i_dn(OU,2)" the second organization unit, and + "ssl_c_i_dn(CN)" retrieves the common name. + The <format> parameter allows you to receive the DN suitable for + consumption by different protocols. Currently supported is rfc2253 for + LDAP v3. + If you'd like to modify the format only you can specify an empty string + and zero for the first two parameters. Example: ssl_c_i_dn(,0,rfc2253) + +ssl_c_key_alg : string + Returns the name of the algorithm used to generate the key of the certificate + presented by the client when the incoming connection was made over an SSL/TLS + transport layer. + +ssl_c_notafter : string + Returns the end date presented by the client as a formatted string + YYMMDDhhmmss[Z] when the incoming connection was made over an SSL/TLS + transport layer. + +ssl_c_notbefore : string + Returns the start date presented by the client as a formatted string + YYMMDDhhmmss[Z] when the incoming connection was made over an SSL/TLS + transport layer. + +ssl_c_s_dn([<entry>[,<occ>[,<format>]]]) : string + When the incoming connection was made over an SSL/TLS transport layer, + returns the full distinguished name of the subject of the certificate + presented by the client when no <entry> is specified, or the value of the + first given entry found from the beginning of the DN. If a positive/negative + occurrence number is specified as the optional second argument, it returns + the value of the nth given entry value from the beginning/end of the DN. + For instance, "ssl_c_s_dn(OU,2)" the second organization unit, and + "ssl_c_s_dn(CN)" retrieves the common name. + The <format> parameter allows you to receive the DN suitable for + consumption by different protocols. Currently supported is rfc2253 for + LDAP v3. + If you'd like to modify the format only you can specify an empty string + and zero for the first two parameters. Example: ssl_c_s_dn(,0,rfc2253) + +ssl_c_serial : binary + Returns the serial of the certificate presented by the client when the + incoming connection was made over an SSL/TLS transport layer. When used for + an ACL, the value(s) to match against can be passed in hexadecimal form. + +ssl_c_sha1 : binary + Returns the SHA-1 fingerprint of the certificate presented by the client when + the incoming connection was made over an SSL/TLS transport layer. This can be + used to stick a client to a server, or to pass this information to a server. + Note that the output is binary, so if you want to pass that signature to the + server, you need to encode it in hex or base64, such as in the example below: + + Example: + http-request set-header X-SSL-Client-SHA1 %[ssl_c_sha1,hex] + +ssl_c_sig_alg : string + Returns the name of the algorithm used to sign the certificate presented by + the client when the incoming connection was made over an SSL/TLS transport + layer. + +ssl_c_used : boolean + Returns true if current SSL session uses a client certificate even if current + connection uses SSL session resumption. See also "ssl_fc_has_crt". + +ssl_c_verify : integer + Returns the verify result error ID when the incoming connection was made over + an SSL/TLS transport layer, otherwise zero if no error is encountered. Please + refer to your SSL library's documentation for an exhaustive list of error + codes. + +ssl_c_version : integer + Returns the version of the certificate presented by the client when the + incoming connection was made over an SSL/TLS transport layer. + +ssl_f_der : binary + Returns the DER formatted certificate presented by the frontend when the + incoming connection was made over an SSL/TLS transport layer. When used for + an ACL, the value(s) to match against can be passed in hexadecimal form. + +ssl_f_i_dn([<entry>[,<occ>[,<format>]]]) : string + When the incoming connection was made over an SSL/TLS transport layer, + returns the full distinguished name of the issuer of the certificate + presented by the frontend when no <entry> is specified, or the value of the + first given entry found from the beginning of the DN. If a positive/negative + occurrence number is specified as the optional second argument, it returns + the value of the nth given entry value from the beginning/end of the DN. + For instance, "ssl_f_i_dn(OU,2)" the second organization unit, and + "ssl_f_i_dn(CN)" retrieves the common name. + The <format> parameter allows you to receive the DN suitable for + consumption by different protocols. Currently supported is rfc2253 for + LDAP v3. + If you'd like to modify the format only you can specify an empty string + and zero for the first two parameters. Example: ssl_f_i_dn(,0,rfc2253) + +ssl_f_key_alg : string + Returns the name of the algorithm used to generate the key of the certificate + presented by the frontend when the incoming connection was made over an + SSL/TLS transport layer. + +ssl_f_notafter : string + Returns the end date presented by the frontend as a formatted string + YYMMDDhhmmss[Z] when the incoming connection was made over an SSL/TLS + transport layer. + +ssl_f_notbefore : string + Returns the start date presented by the frontend as a formatted string + YYMMDDhhmmss[Z] when the incoming connection was made over an SSL/TLS + transport layer. + +ssl_f_s_dn([<entry>[,<occ>[,<format>]]]) : string + When the incoming connection was made over an SSL/TLS transport layer, + returns the full distinguished name of the subject of the certificate + presented by the frontend when no <entry> is specified, or the value of the + first given entry found from the beginning of the DN. If a positive/negative + occurrence number is specified as the optional second argument, it returns + the value of the nth given entry value from the beginning/end of the DN. + For instance, "ssl_f_s_dn(OU,2)" the second organization unit, and + "ssl_f_s_dn(CN)" retrieves the common name. + The <format> parameter allows you to receive the DN suitable for + consumption by different protocols. Currently supported is rfc2253 for + LDAP v3. + If you'd like to modify the format only you can specify an empty string + and zero for the first two parameters. Example: ssl_f_s_dn(,0,rfc2253) + +ssl_f_serial : binary + Returns the serial of the certificate presented by the frontend when the + incoming connection was made over an SSL/TLS transport layer. When used for + an ACL, the value(s) to match against can be passed in hexadecimal form. + +ssl_f_sha1 : binary + Returns the SHA-1 fingerprint of the certificate presented by the frontend + when the incoming connection was made over an SSL/TLS transport layer. This + can be used to know which certificate was chosen using SNI. + +ssl_f_sig_alg : string + Returns the name of the algorithm used to sign the certificate presented by + the frontend when the incoming connection was made over an SSL/TLS transport + layer. + +ssl_f_version : integer + Returns the version of the certificate presented by the frontend when the + incoming connection was made over an SSL/TLS transport layer. + +ssl_fc : boolean + Returns true when the front connection was made via an SSL/TLS transport + layer and is locally deciphered. This means it has matched a socket declared + with a "bind" line having the "ssl" option. + + Example : + # This passes "X-Proto: https" to servers when client connects over SSL + listen http-https + bind :80 + bind :443 ssl crt /etc/haproxy.pem + http-request add-header X-Proto https if { ssl_fc } + +ssl_fc_alg_keysize : integer + Returns the symmetric cipher key size supported in bits when the incoming + connection was made over an SSL/TLS transport layer. + +ssl_fc_alpn : string + This extracts the Application Layer Protocol Negotiation field from an + incoming connection made via a TLS transport layer and locally deciphered by + HAProxy. The result is a string containing the protocol name advertised by + the client. The SSL library must have been built with support for TLS + extensions enabled (check haproxy -vv). Note that the TLS ALPN extension is + not advertised unless the "alpn" keyword on the "bind" line specifies a + protocol list. Also, nothing forces the client to pick a protocol from this + list, any other one may be requested. The TLS ALPN extension is meant to + replace the TLS NPN extension. See also "ssl_fc_npn". + +ssl_fc_cipher : string + Returns the name of the used cipher when the incoming connection was made + over an SSL/TLS transport layer. + +ssl_fc_cipherlist_bin([<filter_option>]) : binary + Returns the binary form of the client hello cipher list. The maximum + returned value length is limited by the shared capture buffer size + controlled by "tune.ssl.capture-buffer-size" setting. Setting + <filter_option> allows to filter returned data. Accepted values: + 0 : return the full list of ciphers (default) + 1 : exclude GREASE (RFC8701) values from the output + + Example: + http-request set-header X-SSL-JA3 %[ssl_fc_protocol_hello_id],\ + %[ssl_fc_cipherlist_bin(1),be2dec(-,2)],\ + %[ssl_fc_extlist_bin(1),be2dec(-,2)],\ + %[ssl_fc_eclist_bin(1),be2dec(-,2)],\ + %[ssl_fc_ecformats_bin,be2dec(-,1)] + acl is_malware req.fhdr(x-ssl-ja3),digest(md5),hex \ + -f /path/to/file/with/malware-ja3.lst + http-request set-header X-Malware True if is_malware + http-request set-header X-Malware False if !is_malware + +ssl_fc_cipherlist_hex([<filter_option>]) : string + Returns the binary form of the client hello cipher list encoded as + hexadecimal. The maximum returned value length is limited by the shared + capture buffer size controlled by "tune.ssl.capture-buffer-size" setting. + Setting <filter_option> allows to filter returned data. Accepted values: + 0 : return the full list of ciphers (default) + 1 : exclude GREASE (RFC8701) values from the output + +ssl_fc_cipherlist_str([<filter_option>]) : string + Returns the decoded text form of the client hello cipher list. The maximum + returned value length is limited by the shared capture buffer size + controlled by "tune.ssl.capture-buffer-size" setting. Setting + <filter_option> allows to filter returned data. Accepted values: + 0 : return the full list of ciphers (default) + 1 : exclude GREASE (RFC8701) values from the output + Note that this sample-fetch is only available with OpenSSL >= 1.0.2. If the + function is not enabled, this sample-fetch returns the hash like + "ssl_fc_cipherlist_xxh". + +ssl_fc_cipherlist_xxh : integer + Returns a xxh64 of the cipher list. This hash can return only if the value + "tune.ssl.capture-buffer-size" is set greater than 0, however the hash take + into account all the data of the cipher list. + +ssl_fc_ecformats_bin : binary + Return the binary form of the client hello supported elliptic curve point + formats. The maximum returned value length is limited by the shared capture + buffer size controlled by "tune.ssl.capture-buffer-size" setting. + + Example: + http-request set-header X-SSL-JA3 %[ssl_fc_protocol_hello_id],\ + %[ssl_fc_cipherlist_bin(1),be2dec(-,2)],\ + %[ssl_fc_extlist_bin(1),be2dec(-,2)],\ + %[ssl_fc_eclist_bin(1),be2dec(-,2)],\ + %[ssl_fc_ecformats_bin,be2dec(-,1)] + acl is_malware req.fhdr(x-ssl-ja3),digest(md5),hex \ + -f /path/to/file/with/malware-ja3.lst + http-request set-header X-Malware True if is_malware + http-request set-header X-Malware False if !is_malware + +ssl_fc_eclist_bin([<filter_option>]) : binary + Returns the binary form of the client hello supported elliptic curves. The + maximum returned value length is limited by the shared capture buffer size + controlled by "tune.ssl.capture-buffer-size" setting. Setting + <filter_option> allows to filter returned data. Accepted values: + 0 : return the full list of supported elliptic curves (default) + 1 : exclude GREASE (RFC8701) values from the output + + Example: + http-request set-header X-SSL-JA3 %[ssl_fc_protocol_hello_id],\ + %[ssl_fc_cipherlist_bin(1),be2dec(-,2)],\ + %[ssl_fc_extlist_bin(1),be2dec(-,2)],\ + %[ssl_fc_eclist_bin(1),be2dec(-,2)],\ + %[ssl_fc_ecformats_bin,be2dec(-,1)] + acl is_malware req.fhdr(x-ssl-ja3),digest(md5),hex \ + -f /path/to/file/with/malware-ja3.lst + http-request set-header X-Malware True if is_malware + http-request set-header X-Malware False if !is_malware + +ssl_fc_extlist_bin([<filter_option>]) : binary + Returns the binary form of the client hello extension list. The maximum + returned value length is limited by the shared capture buffer size + controlled by "tune.ssl.capture-buffer-size" setting. Setting + <filter_option> allows to filter returned data. Accepted values: + 0 : return the full list of extensions (default) + 1 : exclude GREASE (RFC8701) values from the output + + Example: + http-request set-header X-SSL-JA3 %[ssl_fc_protocol_hello_id],\ + %[ssl_fc_cipherlist_bin(1),be2dec(-,2)],\ + %[ssl_fc_extlist_bin(1),be2dec(-,2)],\ + %[ssl_fc_eclist_bin(1),be2dec(-,2)],\ + %[ssl_fc_ecformats_bin,be2dec(-,1)] + acl is_malware req.fhdr(x-ssl-ja3),digest(md5),hex \ + -f /path/to/file/with/malware-ja3.lst + http-request set-header X-Malware True if is_malware + http-request set-header X-Malware False if !is_malware + +ssl_fc_client_random : binary + Returns the client random of the front connection when the incoming connection + was made over an SSL/TLS transport layer. It is useful to to decrypt traffic + sent using ephemeral ciphers. This requires OpenSSL >= 1.1.0, or BoringSSL. + +ssl_fc_client_early_traffic_secret : string + Return the CLIENT_EARLY_TRAFFIC_SECRET as an hexadecimal string for the + front connection when the incoming connection was made over a TLS 1.3 + transport layer. + Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL + keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be + activated with "tune.ssl.keylog on" in the global section. See also + "tune.ssl.keylog" + +ssl_fc_client_handshake_traffic_secret : string + Return the CLIENT_HANDSHAKE_TRAFFIC_SECRET as an hexadecimal string for the + front connection when the incoming connection was made over a TLS 1.3 + transport layer. + Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL + keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be + activated with "tune.ssl.keylog on" in the global section. See also + "tune.ssl.keylog" + +ssl_fc_client_traffic_secret_0 : string + Return the CLIENT_TRAFFIC_SECRET_0 as an hexadecimal string for the + front connection when the incoming connection was made over a TLS 1.3 + transport layer. + Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL + keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be + activated with "tune.ssl.keylog on" in the global section. See also + "tune.ssl.keylog" + +ssl_fc_exporter_secret : string + Return the EXPORTER_SECRET as an hexadecimal string for the + front connection when the incoming connection was made over a TLS 1.3 + transport layer. + Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL + keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be + activated with "tune.ssl.keylog on" in the global section. See also + "tune.ssl.keylog" + +ssl_fc_early_exporter_secret : string + Return the EARLY_EXPORTER_SECRET as an hexadecimal string for the + front connection when the incoming connection was made over an TLS 1.3 + transport layer. + Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL + keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be + activated with "tune.ssl.keylog on" in the global section. See also + "tune.ssl.keylog" + +ssl_fc_err : integer + When the incoming connection was made over an SSL/TLS transport layer, + returns the ID of the last error of the first error stack raised on the + frontend side, or 0 if no error was encountered. It can be used to identify + handshake related errors other than verify ones (such as cipher mismatch), as + well as other read or write errors occurring during the connection's + lifetime. Any error happening during the client's certificate verification + process will not be raised through this fetch but via the existing + "ssl_c_err", "ssl_c_ca_err" and "ssl_c_ca_err_depth" fetches. In order to get + a text description of this error code, you can either use the + "ssl_fc_err_str" sample fetch or use the "openssl errstr" command (which + takes an error code in hexadecimal representation as parameter). Please refer + to your SSL library's documentation to find the exhaustive list of error + codes. + +ssl_fc_err_str : string + When the incoming connection was made over an SSL/TLS transport layer, + returns a string representation of the last error of the first error stack + that was raised on the frontend side. Any error happening during the client's + certificate verification process will not be raised through this fetch. See + also "ssl_fc_err". + +ssl_fc_has_crt : boolean + Returns true if a client certificate is present in an incoming connection over + SSL/TLS transport layer. Useful if 'verify' statement is set to 'optional'. + Note: on SSL session resumption with Session ID or TLS ticket, client + certificate is not present in the current connection but may be retrieved + from the cache or the ticket. So prefer "ssl_c_used" if you want to check if + current SSL session uses a client certificate. + +ssl_fc_has_early : boolean + Returns true if early data were sent, and the handshake didn't happen yet. As + it has security implications, it is useful to be able to refuse those, or + wait until the handshake happened. + +ssl_fc_has_sni : boolean + This checks for the presence of a Server Name Indication TLS extension (SNI) + in an incoming connection was made over an SSL/TLS transport layer. Returns + true when the incoming connection presents a TLS SNI field. This requires + that the SSL library is built with support for TLS extensions enabled (check + haproxy -vv). + +ssl_fc_is_resumed : boolean + Returns true if the SSL/TLS session has been resumed through the use of + SSL session cache or TLS tickets on an incoming connection over an SSL/TLS + transport layer. + +ssl_fc_npn : string + This extracts the Next Protocol Negotiation field from an incoming connection + made via a TLS transport layer and locally deciphered by HAProxy. The result + is a string containing the protocol name advertised by the client. The SSL + library must have been built with support for TLS extensions enabled (check + haproxy -vv). Note that the TLS NPN extension is not advertised unless the + "npn" keyword on the "bind" line specifies a protocol list. Also, nothing + forces the client to pick a protocol from this list, any other one may be + requested. Please note that the TLS NPN extension was replaced with ALPN. + +ssl_fc_protocol : string + Returns the name of the used protocol when the incoming connection was made + over an SSL/TLS transport layer. + +ssl_fc_protocol_hello_id : integer + The version of the TLS protocol by which the client wishes to communicate + during the session as indicated in client hello message. This value can + return only if the value "tune.ssl.capture-buffer-size" is set greater than + 0. + + Example: + http-request set-header X-SSL-JA3 %[ssl_fc_protocol_hello_id],\ + %[ssl_fc_cipherlist_bin(1),be2dec(-,2)],\ + %[ssl_fc_extlist_bin(1),be2dec(-,2)],\ + %[ssl_fc_eclist_bin(1),be2dec(-,2)],\ + %[ssl_fc_ecformats_bin,be2dec(-,1)] + acl is_malware req.fhdr(x-ssl-ja3),digest(md5),hex \ + -f /path/to/file/with/malware-ja3.lst + http-request set-header X-Malware True if is_malware + http-request set-header X-Malware False if !is_malware + +ssl_fc_unique_id : binary + When the incoming connection was made over an SSL/TLS transport layer, + returns the TLS unique ID as defined in RFC5929 section 3. The unique id + can be encoded to base64 using the converter: "ssl_fc_unique_id,base64". + +ssl_fc_server_handshake_traffic_secret : string + Return the SERVER_HANDSHAKE_TRAFFIC_SECRET as an hexadecimal string for the + front connection when the incoming connection was made over a TLS 1.3 + transport layer. + Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL + keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be + activated with "tune.ssl.keylog on" in the global section. See also + "tune.ssl.keylog" + +ssl_fc_server_traffic_secret_0 : string + Return the SERVER_TRAFFIC_SECRET_0 as an hexadecimal string for the + front connection when the incoming connection was made over an TLS 1.3 + transport layer. + Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL + keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be + activated with "tune.ssl.keylog on" in the global section. See also + "tune.ssl.keylog" + +ssl_fc_server_random : binary + Returns the server random of the front connection when the incoming connection + was made over an SSL/TLS transport layer. It is useful to to decrypt traffic + sent using ephemeral ciphers. This requires OpenSSL >= 1.1.0, or BoringSSL. + +ssl_fc_session_id : binary + Returns the SSL ID of the front connection when the incoming connection was + made over an SSL/TLS transport layer. It is useful to stick a given client to + a server. It is important to note that some browsers refresh their session ID + every few minutes. + +ssl_fc_session_key : binary + Returns the SSL session master key of the front connection when the incoming + connection was made over an SSL/TLS transport layer. It is useful to decrypt + traffic sent using ephemeral ciphers. This requires OpenSSL >= 1.1.0, or + BoringSSL. + + +ssl_fc_sni : string + This extracts the Server Name Indication TLS extension (SNI) field from an + incoming connection made via an SSL/TLS transport layer and locally + deciphered by HAProxy. The result (when present) typically is a string + matching the HTTPS host name (253 chars or less). The SSL library must have + been built with support for TLS extensions enabled (check haproxy -vv). + + This fetch is different from "req.ssl_sni" above in that it applies to the + connection being deciphered by HAProxy and not to SSL contents being blindly + forwarded. See also "ssl_fc_sni_end" and "ssl_fc_sni_reg" below. This + requires that the SSL library is built with support for TLS extensions + enabled (check haproxy -vv). + + CAUTION! Except under very specific conditions, it is normally not correct to + use this field as a substitute for the HTTP "Host" header field. For example, + when forwarding an HTTPS connection to a server, the SNI field must be set + from the HTTP Host header field using "req.hdr(host)" and not from the front + SNI value. The reason is that SNI is solely used to select the certificate + the server side will present, and that clients are then allowed to send + requests with different Host values as long as they match the names in the + certificate. As such, "ssl_fc_sni" should normally not be used as an argument + to the "sni" server keyword, unless the backend works in TCP mode. + + ACL derivatives : + ssl_fc_sni_end : suffix match + ssl_fc_sni_reg : regex match + +ssl_fc_use_keysize : integer + Returns the symmetric cipher key size used in bits when the incoming + connection was made over an SSL/TLS transport layer. + +ssl_s_der : binary + Returns the DER formatted certificate presented by the server when the + outgoing connection was made over an SSL/TLS transport layer. When used for + an ACL, the value(s) to match against can be passed in hexadecimal form. + +ssl_s_chain_der : binary + Returns the DER formatted chain certificate presented by the server when the + outgoing connection was made over an SSL/TLS transport layer. When used for + an ACL, the value(s) to match against can be passed in hexadecimal form. One + can parse the result with any lib accepting ASN.1 DER data. It currently + does not support resumed sessions. + +ssl_s_key_alg : string + Returns the name of the algorithm used to generate the key of the certificate + presented by the server when the outgoing connection was made over an + SSL/TLS transport layer. + +ssl_s_notafter : string + Returns the end date presented by the server as a formatted string + YYMMDDhhmmss[Z] when the outgoing connection was made over an SSL/TLS + transport layer. + +ssl_s_notbefore : string + Returns the start date presented by the server as a formatted string + YYMMDDhhmmss[Z] when the outgoing connection was made over an SSL/TLS + transport layer. + +ssl_s_i_dn([<entry>[,<occ>[,<format>]]]) : string + When the outgoing connection was made over an SSL/TLS transport layer, + returns the full distinguished name of the issuer of the certificate + presented by the server when no <entry> is specified, or the value of the + first given entry found from the beginning of the DN. If a positive/negative + occurrence number is specified as the optional second argument, it returns + the value of the nth given entry value from the beginning/end of the DN. + For instance, "ssl_s_i_dn(OU,2)" the second organization unit, and + "ssl_s_i_dn(CN)" retrieves the common name. + The <format> parameter allows you to receive the DN suitable for + consumption by different protocols. Currently supported is rfc2253 for + LDAP v3. + If you'd like to modify the format only you can specify an empty string + and zero for the first two parameters. Example: ssl_s_i_dn(,0,rfc2253) + +ssl_s_s_dn([<entry>[,<occ>[,<format>]]]) : string + When the outgoing connection was made over an SSL/TLS transport layer, + returns the full distinguished name of the subject of the certificate + presented by the server when no <entry> is specified, or the value of the + first given entry found from the beginning of the DN. If a positive/negative + occurrence number is specified as the optional second argument, it returns + the value of the nth given entry value from the beginning/end of the DN. + For instance, "ssl_s_s_dn(OU,2)" the second organization unit, and + "ssl_s_s_dn(CN)" retrieves the common name. + The <format> parameter allows you to receive the DN suitable for + consumption by different protocols. Currently supported is rfc2253 for + LDAP v3. + If you'd like to modify the format only you can specify an empty string + and zero for the first two parameters. Example: ssl_s_s_dn(,0,rfc2253) + +ssl_s_serial : binary + Returns the serial of the certificate presented by the server when the + outgoing connection was made over an SSL/TLS transport layer. When used for + an ACL, the value(s) to match against can be passed in hexadecimal form. + +ssl_s_sha1 : binary + Returns the SHA-1 fingerprint of the certificate presented by the server + when the outgoing connection was made over an SSL/TLS transport layer. This + can be used to know which certificate was chosen using SNI. + +ssl_s_sig_alg : string + Returns the name of the algorithm used to sign the certificate presented by + the server when the outgoing connection was made over an SSL/TLS transport + layer. + +ssl_s_version : integer + Returns the version of the certificate presented by the server when the + outgoing connection was made over an SSL/TLS transport layer. + +7.3.5. Fetching samples from buffer contents (Layer 6) +------------------------------------------------------ + +Fetching samples from buffer contents is a bit different from the previous +sample fetches above because the sampled data are ephemeral. These data can +only be used when they're available and will be lost when they're forwarded. +For this reason, samples fetched from buffer contents during a request cannot +be used in a response for example. Even while the data are being fetched, they +can change. Sometimes it is necessary to set some delays or combine multiple +sample fetch methods to ensure that the expected data are complete and usable, +for example through TCP request content inspection. Please see the "tcp-request +content" keyword for more detailed information on the subject. + +Warning : Following sample fetches are ignored if used from HTTP proxies. They + only deal with raw contents found in the buffers. On their side, + HTTP proxies use structured content. Thus raw representation of + these data are meaningless. A warning is emitted if an ACL relies on + one of the following sample fetches. But it is not possible to detect + all invalid usage (for instance inside a log-format string or a + sample expression). So be careful. + +distcc_body(<token>[,<occ>]) : binary + Parses a distcc message and returns the body associated to occurrence #<occ> + of the token <token>. Occurrences start at 1, and when unspecified, any may + match though in practice only the first one is checked for now. This can be + used to extract file names or arguments in files built using distcc through + HAProxy. Please refer to distcc's protocol documentation for the complete + list of supported tokens. + +distcc_param(<token>[,<occ>]) : integer + Parses a distcc message and returns the parameter associated to occurrence + #<occ> of the token <token>. Occurrences start at 1, and when unspecified, + any may match though in practice only the first one is checked for now. This + can be used to extract certain information such as the protocol version, the + file size or the argument in files built using distcc through HAProxy. + Another use case consists in waiting for the start of the preprocessed file + contents before connecting to the server to avoid keeping idle connections. + Please refer to distcc's protocol documentation for the complete list of + supported tokens. + + Example : + # wait up to 20s for the pre-processed file to be uploaded + tcp-request inspect-delay 20s + tcp-request content accept if { distcc_param(DOTI) -m found } + # send large files to the big farm + use_backend big_farm if { distcc_param(DOTI) gt 1000000 } + +payload(<offset>,<length>) : binary (deprecated) + This is an alias for "req.payload" when used in the context of a request (e.g. + "stick on", "stick match"), and for "res.payload" when used in the context of + a response such as in "stick store response". + +payload_lv(<offset1>,<length>[,<offset2>]) : binary (deprecated) + This is an alias for "req.payload_lv" when used in the context of a request + (e.g. "stick on", "stick match"), and for "res.payload_lv" when used in the + context of a response such as in "stick store response". + +req.len : integer +req_len : integer (deprecated) + Returns an integer value corresponding to the number of bytes present in the + request buffer. This is mostly used in ACL. It is important to understand + that this test does not return false as long as the buffer is changing. This + means that a check with equality to zero will almost always immediately match + at the beginning of the session, while a test for more data will wait for + that data to come in and return false only when HAProxy is certain that no + more data will come in. This test was designed to be used with TCP request + content inspection. + +req.payload(<offset>,<length>) : binary + This extracts a binary block of <length> bytes and starting at byte <offset> + in the request buffer. As a special case, if the <length> argument is zero, + the the whole buffer from <offset> to the end is extracted. This can be used + with ACLs in order to check for the presence of some content in a buffer at + any location. + + ACL derivatives : + req.payload(<offset>,<length>) : hex binary match + +req.payload_lv(<offset1>,<length>[,<offset2>]) : binary + This extracts a binary block whose size is specified at <offset1> for <length> + bytes, and which starts at <offset2> if specified or just after the length in + the request buffer. The <offset2> parameter also supports relative offsets if + prepended with a '+' or '-' sign. + + ACL derivatives : + req.payload_lv(<offset1>,<length>[,<offset2>]) : hex binary match + + Example : please consult the example from the "stick store-response" keyword. + +req.proto_http : boolean +req_proto_http : boolean (deprecated) + Returns true when data in the request buffer look like HTTP and correctly + parses as such. It is the same parser as the common HTTP request parser which + is used so there should be no surprises. The test does not match until the + request is complete, failed or timed out. This test may be used to report the + protocol in TCP logs, but the biggest use is to block TCP request analysis + until a complete HTTP request is present in the buffer, for example to track + a header. + + Example: + # track request counts per "base" (concatenation of Host+URL) + tcp-request inspect-delay 10s + tcp-request content reject if !HTTP + tcp-request content track-sc0 base table req-rate + +req.rdp_cookie([<name>]) : string +rdp_cookie([<name>]) : string (deprecated) + When the request buffer looks like the RDP protocol, extracts the RDP cookie + <name>, or any cookie if unspecified. The parser only checks for the first + cookie, as illustrated in the RDP protocol specification. The cookie name is + case insensitive. Generally the "MSTS" cookie name will be used, as it can + contain the user name of the client connecting to the server if properly + configured on the client. The "MSTSHASH" cookie is often used as well for + session stickiness to servers. + + This differs from "balance rdp-cookie" in that any balancing algorithm may be + used and thus the distribution of clients to backend servers is not linked to + a hash of the RDP cookie. It is envisaged that using a balancing algorithm + such as "balance roundrobin" or "balance leastconn" will lead to a more even + distribution of clients to backend servers than the hash used by "balance + rdp-cookie". + + ACL derivatives : + req.rdp_cookie([<name>]) : exact string match + + Example : + listen tse-farm + bind 0.0.0.0:3389 + # wait up to 5s for an RDP cookie in the request + tcp-request inspect-delay 5s + tcp-request content accept if RDP_COOKIE + # apply RDP cookie persistence + persist rdp-cookie + # Persist based on the mstshash cookie + # This is only useful makes sense if + # balance rdp-cookie is not used + stick-table type string size 204800 + stick on req.rdp_cookie(mstshash) + server srv1 1.1.1.1:3389 + server srv1 1.1.1.2:3389 + + See also : "balance rdp-cookie", "persist rdp-cookie", "tcp-request" and the + "req.rdp_cookie" ACL. + +req.rdp_cookie_cnt([name]) : integer +rdp_cookie_cnt([name]) : integer (deprecated) + Tries to parse the request buffer as RDP protocol, then returns an integer + corresponding to the number of RDP cookies found. If an optional cookie name + is passed, only cookies matching this name are considered. This is mostly + used in ACL. + + ACL derivatives : + req.rdp_cookie_cnt([<name>]) : integer match + +req.ssl_alpn : string + Returns a string containing the values of the Application-Layer Protocol + Negotiation (ALPN) TLS extension (RFC7301), sent by the client within the SSL + ClientHello message. Note that this only applies to raw contents found in the + request buffer and not to the contents deciphered via an SSL data layer, so + this will not work with "bind" lines having the "ssl" option. This is useful + in ACL to make a routing decision based upon the ALPN preferences of a TLS + client, like in the example below. See also "ssl_fc_alpn". + + Examples : + # Wait for a client hello for at most 5 seconds + tcp-request inspect-delay 5s + tcp-request content accept if { req.ssl_hello_type 1 } + use_backend bk_acme if { req.ssl_alpn acme-tls/1 } + default_backend bk_default + +req.ssl_ec_ext : boolean + Returns a boolean identifying if client sent the Supported Elliptic Curves + Extension as defined in RFC4492, section 5.1. within the SSL ClientHello + message. This can be used to present ECC compatible clients with EC + certificate and to use RSA for all others, on the same IP address. Note that + this only applies to raw contents found in the request buffer and not to + contents deciphered via an SSL data layer, so this will not work with "bind" + lines having the "ssl" option. + +req.ssl_hello_type : integer +req_ssl_hello_type : integer (deprecated) + Returns an integer value containing the type of the SSL hello message found + in the request buffer if the buffer contains data that parse as a complete + SSL (v3 or superior) client hello message. Note that this only applies to raw + contents found in the request buffer and not to contents deciphered via an + SSL data layer, so this will not work with "bind" lines having the "ssl" + option. This is mostly used in ACL to detect presence of an SSL hello message + that is supposed to contain an SSL session ID usable for stickiness. + +req.ssl_sni : string +req_ssl_sni : string (deprecated) + Returns a string containing the value of the Server Name TLS extension sent + by a client in a TLS stream passing through the request buffer if the buffer + contains data that parse as a complete SSL (v3 or superior) client hello + message. Note that this only applies to raw contents found in the request + buffer and not to contents deciphered via an SSL data layer, so this will not + work with "bind" lines having the "ssl" option. This will only work for actual + implicit TLS based protocols like HTTPS (443), IMAPS (993), SMTPS (465), + however it will not work for explicit TLS based protocols, like SMTP (25/587) + or IMAP (143). SNI normally contains the name of the host the client tries to + connect to (for recent browsers). SNI is useful for allowing or denying access + to certain hosts when SSL/TLS is used by the client. This test was designed to + be used with TCP request content inspection. If content switching is needed, + it is recommended to first wait for a complete client hello (type 1), like in + the example below. See also "ssl_fc_sni". + + ACL derivatives : + req.ssl_sni : exact string match + + Examples : + # Wait for a client hello for at most 5 seconds + tcp-request inspect-delay 5s + tcp-request content accept if { req.ssl_hello_type 1 } + use_backend bk_allow if { req.ssl_sni -f allowed_sites } + default_backend bk_sorry_page + +req.ssl_st_ext : integer + Returns 0 if the client didn't send a SessionTicket TLS Extension (RFC5077) + Returns 1 if the client sent SessionTicket TLS Extension + Returns 2 if the client also sent non-zero length TLS SessionTicket + Note that this only applies to raw contents found in the request buffer and + not to contents deciphered via an SSL data layer, so this will not work with + "bind" lines having the "ssl" option. This can for example be used to detect + whether the client sent a SessionTicket or not and stick it accordingly, if + no SessionTicket then stick on SessionID or don't stick as there's no server + side state is there when SessionTickets are in use. + +req.ssl_ver : integer +req_ssl_ver : integer (deprecated) + Returns an integer value containing the version of the SSL/TLS protocol of a + stream present in the request buffer. Both SSLv2 hello messages and SSLv3 + messages are supported. TLSv1 is announced as SSL version 3.1. The value is + composed of the major version multiplied by 65536, added to the minor + version. Note that this only applies to raw contents found in the request + buffer and not to contents deciphered via an SSL data layer, so this will not + work with "bind" lines having the "ssl" option. The ACL version of the test + matches against a decimal notation in the form MAJOR.MINOR (e.g. 3.1). This + fetch is mostly used in ACL. + + ACL derivatives : + req.ssl_ver : decimal match + +res.len : integer + Returns an integer value corresponding to the number of bytes present in the + response buffer. This is mostly used in ACL. It is important to understand + that this test does not return false as long as the buffer is changing. This + means that a check with equality to zero will almost always immediately match + at the beginning of the session, while a test for more data will wait for + that data to come in and return false only when HAProxy is certain that no + more data will come in. This test was designed to be used with TCP response + content inspection. But it may also be used in tcp-check based expect rules. + +res.payload(<offset>,<length>) : binary + This extracts a binary block of <length> bytes and starting at byte <offset> + in the response buffer. As a special case, if the <length> argument is zero, + the whole buffer from <offset> to the end is extracted. This can be used + with ACLs in order to check for the presence of some content in a buffer at + any location. It may also be used in tcp-check based expect rules. + +res.payload_lv(<offset1>,<length>[,<offset2>]) : binary + This extracts a binary block whose size is specified at <offset1> for <length> + bytes, and which starts at <offset2> if specified or just after the length in + the response buffer. The <offset2> parameter also supports relative offsets + if prepended with a '+' or '-' sign. It may also be used in tcp-check based + expect rules. + + Example : please consult the example from the "stick store-response" keyword. + +res.ssl_hello_type : integer +rep_ssl_hello_type : integer (deprecated) + Returns an integer value containing the type of the SSL hello message found + in the response buffer if the buffer contains data that parses as a complete + SSL (v3 or superior) hello message. Note that this only applies to raw + contents found in the response buffer and not to contents deciphered via an + SSL data layer, so this will not work with "server" lines having the "ssl" + option. This is mostly used in ACL to detect presence of an SSL hello message + that is supposed to contain an SSL session ID usable for stickiness. + +wait_end : boolean + This fetch either returns true when the inspection period is over, or does + not fetch. It is only used in ACLs, in conjunction with content analysis to + avoid returning a wrong verdict early. It may also be used to delay some + actions, such as a delayed reject for some special addresses. Since it either + stops the rules evaluation or immediately returns true, it is recommended to + use this acl as the last one in a rule. Please note that the default ACL + "WAIT_END" is always usable without prior declaration. This test was designed + to be used with TCP request content inspection. + + Examples : + # delay every incoming request by 2 seconds + tcp-request inspect-delay 2s + tcp-request content accept if WAIT_END + + # don't immediately tell bad guys they are rejected + tcp-request inspect-delay 10s + acl goodguys src 10.0.0.0/24 + acl badguys src 10.0.1.0/24 + tcp-request content accept if goodguys + tcp-request content reject if badguys WAIT_END + tcp-request content reject + + +7.3.6. Fetching HTTP samples (Layer 7) +-------------------------------------- + +It is possible to fetch samples from HTTP contents, requests and responses. +This application layer is also called layer 7. It is only possible to fetch the +data in this section when a full HTTP request or response has been parsed from +its respective request or response buffer. This is always the case with all +HTTP specific rules and for sections running with "mode http". When using TCP +content inspection, it may be necessary to support an inspection delay in order +to let the request or response come in first. These fetches may require a bit +more CPU resources than the layer 4 ones, but not much since the request and +response are indexed. + +Note : Regarding HTTP processing from the tcp-request content rules, everything + will work as expected from an HTTP proxy. However, from a TCP proxy, + without an HTTP upgrade, it will only work for HTTP/1 content. For + HTTP/2 content, only the preface is visible. Thus, it is only possible + to rely to "req.proto_http", "req.ver" and eventually "method" sample + fetches. All other L7 sample fetches will fail. After an HTTP upgrade, + they will work in the same manner than from an HTTP proxy. + +base : string + This returns the concatenation of the first Host header and the path part of + the request, which starts at the first slash and ends before the question + mark. It can be useful in virtual hosted environments to detect URL abuses as + well as to improve shared caches efficiency. Using this with a limited size + stick table also allows one to collect statistics about most commonly + requested objects by host/path. With ACLs it can allow simple content + switching rules involving the host and the path at the same time, such as + "www.example.com/favicon.ico". See also "path" and "uri". + + ACL derivatives : + base : exact string match + base_beg : prefix match + base_dir : subdir match + base_dom : domain match + base_end : suffix match + base_len : length match + base_reg : regex match + base_sub : substring match + +base32 : integer + This returns a 32-bit hash of the value returned by the "base" fetch method + above. This is useful to track per-URL activity on high traffic sites without + having to store all URLs. Instead a shorter hash is stored, saving a lot of + memory. The output type is an unsigned integer. The hash function used is + SDBM with full avalanche on the output. Technically, base32 is exactly equal + to "base,sdbm(1)". + +base32+src : binary + This returns the concatenation of the base32 fetch above and the src fetch + below. The resulting type is of type binary, with a size of 8 or 20 bytes + depending on the source address family. This can be used to track per-IP, + per-URL counters. + +baseq : string + This returns the concatenation of the first Host header and the path part of + the request with the query-string, which starts at the first slash. Using this + instead of "base" allows one to properly identify the target resource, for + statistics or caching use cases. See also "path", "pathq" and "base". + +capture.req.hdr(<idx>) : string + This extracts the content of the header captured by the "capture request + header", idx is the position of the capture keyword in the configuration. + The first entry is an index of 0. See also: "capture request header". + +capture.req.method : string + This extracts the METHOD of an HTTP request. It can be used in both request + and response. Unlike "method", it can be used in both request and response + because it's allocated. + +capture.req.uri : string + This extracts the request's URI, which starts at the first slash and ends + before the first space in the request (without the host part). Unlike "path" + and "url", it can be used in both request and response because it's + allocated. + +capture.req.ver : string + This extracts the request's HTTP version and returns either "HTTP/1.0" or + "HTTP/1.1". Unlike "req.ver", it can be used in both request, response, and + logs because it relies on a persistent flag. + +capture.res.hdr(<idx>) : string + This extracts the content of the header captured by the "capture response + header", idx is the position of the capture keyword in the configuration. + The first entry is an index of 0. + See also: "capture response header" + +capture.res.ver : string + This extracts the response's HTTP version and returns either "HTTP/1.0" or + "HTTP/1.1". Unlike "res.ver", it can be used in logs because it relies on a + persistent flag. + +req.body : binary + This returns the HTTP request's available body as a block of data. It is + recommended to use "option http-buffer-request" to be sure to wait, as much + as possible, for the request's body. + +req.body_param([<name>) : string + This fetch assumes that the body of the POST request is url-encoded. The user + can check if the "content-type" contains the value + "application/x-www-form-urlencoded". This extracts the first occurrence of the + parameter <name> in the body, which ends before '&'. The parameter name is + case-sensitive. If no name is given, any parameter will match, and the first + one will be returned. The result is a string corresponding to the value of the + parameter <name> as presented in the request body (no URL decoding is + performed). Note that the ACL version of this fetch iterates over multiple + parameters and will iteratively report all parameters values if no name is + given. + +req.body_len : integer + This returns the length of the HTTP request's available body in bytes. It may + be lower than the advertised length if the body is larger than the buffer. It + is recommended to use "option http-buffer-request" to be sure to wait, as + much as possible, for the request's body. + +req.body_size : integer + This returns the advertised length of the HTTP request's body in bytes. It + will represent the advertised Content-Length header, or the size of the + available data in case of chunked encoding. + +req.cook([<name>]) : string +cook([<name>]) : string (deprecated) + This extracts the last occurrence of the cookie name <name> on a "Cookie" + header line from the request, and returns its value as string. If no name is + specified, the first cookie value is returned. When used with ACLs, all + matching cookies are evaluated. Spaces around the name and the value are + ignored as requested by the Cookie header specification (RFC6265). The cookie + name is case-sensitive. Empty cookies are valid, so an empty cookie may very + well return an empty value if it is present. Use the "found" match to detect + presence. Use the res.cook() variant for response cookies sent by the server. + + ACL derivatives : + req.cook([<name>]) : exact string match + req.cook_beg([<name>]) : prefix match + req.cook_dir([<name>]) : subdir match + req.cook_dom([<name>]) : domain match + req.cook_end([<name>]) : suffix match + req.cook_len([<name>]) : length match + req.cook_reg([<name>]) : regex match + req.cook_sub([<name>]) : substring match + +req.cook_cnt([<name>]) : integer +cook_cnt([<name>]) : integer (deprecated) + Returns an integer value representing the number of occurrences of the cookie + <name> in the request, or all cookies if <name> is not specified. + +req.cook_val([<name>]) : integer +cook_val([<name>]) : integer (deprecated) + This extracts the last occurrence of the cookie name <name> on a "Cookie" + header line from the request, and converts its value to an integer which is + returned. If no name is specified, the first cookie value is returned. When + used in ACLs, all matching names are iterated over until a value matches. + +cookie([<name>]) : string (deprecated) + This extracts the last occurrence of the cookie name <name> on a "Cookie" + header line from the request, or a "Set-Cookie" header from the response, and + returns its value as a string. A typical use is to get multiple clients + sharing a same profile use the same server. This can be similar to what + "appsession" did with the "request-learn" statement, but with support for + multi-peer synchronization and state keeping across restarts. If no name is + specified, the first cookie value is returned. This fetch should not be used + anymore and should be replaced by req.cook() or res.cook() instead as it + ambiguously uses the direction based on the context where it is used. + +hdr([<name>[,<occ>]]) : string + This is equivalent to req.hdr() when used on requests, and to res.hdr() when + used on responses. Please refer to these respective fetches for more details. + In case of doubt about the fetch direction, please use the explicit ones. + Note that contrary to the hdr() sample fetch method, the hdr_* ACL keywords + unambiguously apply to the request headers. + +req.fhdr(<name>[,<occ>]) : string + This returns the full value of the last occurrence of header <name> in an + HTTP request. It differs from req.hdr() in that any commas present in the + value are returned and are not used as delimiters. This is sometimes useful + with headers such as User-Agent. + + When used from an ACL, all occurrences are iterated over until a match is + found. + + Optionally, a specific occurrence might be specified as a position number. + Positive values indicate a position from the first occurrence, with 1 being + the first one. Negative values indicate positions relative to the last one, + with -1 being the last one. + +req.fhdr_cnt([<name>]) : integer + Returns an integer value representing the number of occurrences of request + header field name <name>, or the total number of header fields if <name> is + not specified. Like req.fhdr() it differs from res.hdr_cnt() by not splitting + headers at commas. + +req.hdr([<name>[,<occ>]]) : string + This returns the last comma-separated value of the header <name> in an HTTP + request. The fetch considers any comma as a delimiter for distinct values. + This is useful if you need to process headers that are defined to be a list + of values, such as Accept, or X-Forwarded-For. If full-line headers are + desired instead, use req.fhdr(). Please carefully check RFC 7231 to know how + certain headers are supposed to be parsed. Also, some of them are case + insensitive (e.g. Connection). + + When used from an ACL, all occurrences are iterated over until a match is + found. + + Optionally, a specific occurrence might be specified as a position number. + Positive values indicate a position from the first occurrence, with 1 being + the first one. Negative values indicate positions relative to the last one, + with -1 being the last one. + + A typical use is with the X-Forwarded-For header once converted to IP, + associated with an IP stick-table. + + ACL derivatives : + hdr([<name>[,<occ>]]) : exact string match + hdr_beg([<name>[,<occ>]]) : prefix match + hdr_dir([<name>[,<occ>]]) : subdir match + hdr_dom([<name>[,<occ>]]) : domain match + hdr_end([<name>[,<occ>]]) : suffix match + hdr_len([<name>[,<occ>]]) : length match + hdr_reg([<name>[,<occ>]]) : regex match + hdr_sub([<name>[,<occ>]]) : substring match + +req.hdr_cnt([<name>]) : integer +hdr_cnt([<header>]) : integer (deprecated) + Returns an integer value representing the number of occurrences of request + header field name <name>, or the total number of header field values if + <name> is not specified. Like req.hdr() it counts each comma separated + part of the header's value. If counting of full-line headers is desired, + then req.fhdr_cnt() should be used instead. + + With ACLs, it can be used to detect presence, absence or abuse of a specific + header, as well as to block request smuggling attacks by rejecting requests + which contain more than one of certain headers. + + Refer to req.hdr() for more information on header matching. + +req.hdr_ip([<name>[,<occ>]]) : ip +hdr_ip([<name>[,<occ>]]) : ip (deprecated) + This extracts the last occurrence of header <name> in an HTTP request, + converts it to an IPv4 or IPv6 address and returns this address. When used + with ACLs, all occurrences are checked, and if <name> is omitted, every value + of every header is checked. The parser strictly adheres to the format + described in RFC7239, with the extension that IPv4 addresses may optionally + be followed by a colon (':') and a valid decimal port number (0 to 65535), + which will be silently dropped. All other forms will not match and will + cause the address to be ignored. + + The <occ> parameter is processed as with req.hdr(). + + A typical use is with the X-Forwarded-For and X-Client-IP headers. + +req.hdr_val([<name>[,<occ>]]) : integer +hdr_val([<name>[,<occ>]]) : integer (deprecated) + This extracts the last occurrence of header <name> in an HTTP request, and + converts it to an integer value. When used with ACLs, all occurrences are + checked, and if <name> is omitted, every value of every header is checked. + + The <occ> parameter is processed as with req.hdr(). + + A typical use is with the X-Forwarded-For header. + +req.hdrs : string + Returns the current request headers as string including the last empty line + separating headers from the request body. The last empty line can be used to + detect a truncated header block. This sample fetch is useful for some SPOE + headers analyzers and for advanced logging. + +req.hdrs_bin : binary + Returns the current request headers contained in preparsed binary form. This + is useful for offloading some processing with SPOE. Each string is described + by a length followed by the number of bytes indicated in the length. The + length is represented using the variable integer encoding detailed in the + SPOE documentation. The end of the list is marked by a couple of empty header + names and values (length of 0 for both). + + *(<str:header-name><str:header-value>)<empty string><empty string> + + int: refer to the SPOE documentation for the encoding + str: <int:length><bytes> + +http_auth(<userlist>) : boolean + Returns a boolean indicating whether the authentication data received from + the client match a username & password stored in the specified userlist. This + fetch function is not really useful outside of ACLs. Currently only http + basic auth is supported. + +http_auth_bearer([<header>]) : string + Returns the client-provided token found in the authorization data when the + Bearer scheme is used (to send JSON Web Tokens for instance). No check is + performed on the data sent by the client. + If a specific <header> is supplied, it will parse this header instead of the + Authorization one. + +http_auth_group(<userlist>) : string + Returns a string corresponding to the user name found in the authentication + data received from the client if both the user name and password are valid + according to the specified userlist. The main purpose is to use it in ACLs + where it is then checked whether the user belongs to any group within a list. + This fetch function is not really useful outside of ACLs. Currently only http + basic auth is supported. + + ACL derivatives : + http_auth_group(<userlist>) : group ... + Returns true when the user extracted from the request and whose password is + valid according to the specified userlist belongs to at least one of the + groups. + +http_auth_pass : string + Returns the user's password found in the authentication data received from + the client, as supplied in the Authorization header. Not checks are + performed by this sample fetch. Only Basic authentication is supported. + +http_auth_type : string + Returns the authentication method found in the authentication data received from + the client, as supplied in the Authorization header. Not checks are + performed by this sample fetch. Only Basic authentication is supported. + +http_auth_user : string + Returns the user name found in the authentication data received from the + client, as supplied in the Authorization header. Not checks are performed by + this sample fetch. Only Basic authentication is supported. + +http_first_req : boolean + Returns true when the request being processed is the first one of the + connection. This can be used to add or remove headers that may be missing + from some requests when a request is not the first one, or to help grouping + requests in the logs. + +method : integer + string + Returns an integer value corresponding to the method in the HTTP request. For + example, "GET" equals 1 (check sources to establish the matching). Value 9 + means "other method" and may be converted to a string extracted from the + stream. This should not be used directly as a sample, this is only meant to + be used from ACLs, which transparently convert methods from patterns to these + integer + string values. Some predefined ACL already check for most common + methods. + + ACL derivatives : + method : case insensitive method match + + Example : + # only accept GET and HEAD requests + acl valid_method method GET HEAD + http-request deny if ! valid_method + +path : string + This extracts the request's URL path, which starts at the first slash and + ends before the question mark (without the host part). A typical use is with + prefetch-capable caches, and with portals which need to aggregate multiple + information from databases and keep them in caches. Note that with outgoing + caches, it would be wiser to use "url" instead. With ACLs, it's typically + used to match exact file names (e.g. "/login.php"), or directory parts using + the derivative forms. See also the "url" and "base" fetch methods. + + ACL derivatives : + path : exact string match + path_beg : prefix match + path_dir : subdir match + path_dom : domain match + path_end : suffix match + path_len : length match + path_reg : regex match + path_sub : substring match + +pathq : string + This extracts the request's URL path with the query-string, which starts at + the first slash. This sample fetch is pretty handy to always retrieve a + relative URI, excluding the scheme and the authority part, if any. Indeed, + while it is the common representation for an HTTP/1.1 request target, in + HTTP/2, an absolute URI is often used. This sample fetch will return the same + result in both cases. + +query : string + This extracts the request's query string, which starts after the first + question mark. If no question mark is present, this fetch returns nothing. If + a question mark is present but nothing follows, it returns an empty string. + This means it's possible to easily know whether a query string is present + using the "found" matching method. This fetch is the complement of "path" + which stops before the question mark. + +req.hdr_names([<delim>]) : string + This builds a string made from the concatenation of all header names as they + appear in the request when the rule is evaluated. The default delimiter is + the comma (',') but it may be overridden as an optional argument <delim>. In + this case, only the first character of <delim> is considered. + +req.ver : string +req_ver : string (deprecated) + Returns the version string from the HTTP request, for example "1.1". This can + be useful for logs, but is mostly there for ACL. Some predefined ACL already + check for versions 1.0 and 1.1. + + ACL derivatives : + req.ver : exact string match + +res.body : binary + This returns the HTTP response's available body as a block of data. Unlike + the request side, there is no directive to wait for the response's body. This + sample fetch is really useful (and usable) in the health-check context. + + It may be used in tcp-check based expect rules. + +res.body_len : integer + This returns the length of the HTTP response available body in bytes. Unlike + the request side, there is no directive to wait for the response's body. This + sample fetch is really useful (and usable) in the health-check context. + + It may be used in tcp-check based expect rules. + +res.body_size : integer + This returns the advertised length of the HTTP response body in bytes. It + will represent the advertised Content-Length header, or the size of the + available data in case of chunked encoding. Unlike the request side, there is + no directive to wait for the response body. This sample fetch is really + useful (and usable) in the health-check context. + + It may be used in tcp-check based expect rules. + +res.cache_hit : boolean + Returns the boolean "true" value if the response has been built out of an + HTTP cache entry, otherwise returns boolean "false". + +res.cache_name : string + Returns a string containing the name of the HTTP cache that was used to + build the HTTP response if res.cache_hit is true, otherwise returns an + empty string. + +res.comp : boolean + Returns the boolean "true" value if the response has been compressed by + HAProxy, otherwise returns boolean "false". This may be used to add + information in the logs. + +res.comp_algo : string + Returns a string containing the name of the algorithm used if the response + was compressed by HAProxy, for example : "deflate". This may be used to add + some information in the logs. + +res.cook([<name>]) : string +scook([<name>]) : string (deprecated) + This extracts the last occurrence of the cookie name <name> on a "Set-Cookie" + header line from the response, and returns its value as string. If no name is + specified, the first cookie value is returned. + + It may be used in tcp-check based expect rules. + + ACL derivatives : + res.scook([<name>] : exact string match + +res.cook_cnt([<name>]) : integer +scook_cnt([<name>]) : integer (deprecated) + Returns an integer value representing the number of occurrences of the cookie + <name> in the response, or all cookies if <name> is not specified. This is + mostly useful when combined with ACLs to detect suspicious responses. + + It may be used in tcp-check based expect rules. + +res.cook_val([<name>]) : integer +scook_val([<name>]) : integer (deprecated) + This extracts the last occurrence of the cookie name <name> on a "Set-Cookie" + header line from the response, and converts its value to an integer which is + returned. If no name is specified, the first cookie value is returned. + + It may be used in tcp-check based expect rules. + +res.fhdr([<name>[,<occ>]]) : string + This fetch works like the req.fhdr() fetch with the difference that it acts + on the headers within an HTTP response. + + Like req.fhdr() the res.fhdr() fetch returns full values. If the header is + defined to be a list you should use res.hdr(). + + This fetch is sometimes useful with headers such as Date or Expires. + + It may be used in tcp-check based expect rules. + +res.fhdr_cnt([<name>]) : integer + This fetch works like the req.fhdr_cnt() fetch with the difference that it + acts on the headers within an HTTP response. + + Like req.fhdr_cnt() the res.fhdr_cnt() fetch acts on full values. If the + header is defined to be a list you should use res.hdr_cnt(). + + It may be used in tcp-check based expect rules. + +res.hdr([<name>[,<occ>]]) : string +shdr([<name>[,<occ>]]) : string (deprecated) + This fetch works like the req.hdr() fetch with the difference that it acts + on the headers within an HTTP response. + + Like req.hdr() the res.hdr() fetch considers the comma to be a delimiter. If + this is not desired res.fhdr() should be used. + + It may be used in tcp-check based expect rules. + + ACL derivatives : + res.hdr([<name>[,<occ>]]) : exact string match + res.hdr_beg([<name>[,<occ>]]) : prefix match + res.hdr_dir([<name>[,<occ>]]) : subdir match + res.hdr_dom([<name>[,<occ>]]) : domain match + res.hdr_end([<name>[,<occ>]]) : suffix match + res.hdr_len([<name>[,<occ>]]) : length match + res.hdr_reg([<name>[,<occ>]]) : regex match + res.hdr_sub([<name>[,<occ>]]) : substring match + +res.hdr_cnt([<name>]) : integer +shdr_cnt([<name>]) : integer (deprecated) + This fetch works like the req.hdr_cnt() fetch with the difference that it + acts on the headers within an HTTP response. + + Like req.hdr_cnt() the res.hdr_cnt() fetch considers the comma to be a + delimiter. If this is not desired res.fhdr_cnt() should be used. + + It may be used in tcp-check based expect rules. + +res.hdr_ip([<name>[,<occ>]]) : ip +shdr_ip([<name>[,<occ>]]) : ip (deprecated) + This fetch works like the req.hdr_ip() fetch with the difference that it + acts on the headers within an HTTP response. + + This can be useful to learn some data into a stick table. + + It may be used in tcp-check based expect rules. + +res.hdr_names([<delim>]) : string + This builds a string made from the concatenation of all header names as they + appear in the response when the rule is evaluated. The default delimiter is + the comma (',') but it may be overridden as an optional argument <delim>. In + this case, only the first character of <delim> is considered. + + It may be used in tcp-check based expect rules. + +res.hdr_val([<name>[,<occ>]]) : integer +shdr_val([<name>[,<occ>]]) : integer (deprecated) + This fetch works like the req.hdr_val() fetch with the difference that it + acts on the headers within an HTTP response. + + This can be useful to learn some data into a stick table. + + It may be used in tcp-check based expect rules. + +res.hdrs : string + Returns the current response headers as string including the last empty line + separating headers from the request body. The last empty line can be used to + detect a truncated header block. This sample fetch is useful for some SPOE + headers analyzers and for advanced logging. + + It may also be used in tcp-check based expect rules. + +res.hdrs_bin : binary + Returns the current response headers contained in preparsed binary form. This + is useful for offloading some processing with SPOE. It may be used in + tcp-check based expect rules. Each string is described by a length followed + by the number of bytes indicated in the length. The length is represented + using the variable integer encoding detailed in the SPOE documentation. The + end of the list is marked by a couple of empty header names and values + (length of 0 for both). + + *(<str:header-name><str:header-value>)<empty string><empty string> + + int: refer to the SPOE documentation for the encoding + str: <int:length><bytes> + +res.ver : string +resp_ver : string (deprecated) + Returns the version string from the HTTP response, for example "1.1". This + can be useful for logs, but is mostly there for ACL. + + It may be used in tcp-check based expect rules. + + ACL derivatives : + resp.ver : exact string match + +set-cookie([<name>]) : string (deprecated) + This extracts the last occurrence of the cookie name <name> on a "Set-Cookie" + header line from the response and uses the corresponding value to match. This + can be comparable to what "appsession" did with default options, but with + support for multi-peer synchronization and state keeping across restarts. + + This fetch function is deprecated and has been superseded by the "res.cook" + fetch. This keyword will disappear soon. + +status : integer + Returns an integer containing the HTTP status code in the HTTP response, for + example, 302. It is mostly used within ACLs and integer ranges, for example, + to remove any Location header if the response is not a 3xx. + + It may be used in tcp-check based expect rules. + +unique-id : string + Returns the unique-id attached to the request. The directive + "unique-id-format" must be set. If it is not set, the unique-id sample fetch + fails. Note that the unique-id is usually used with HTTP requests, however this + sample fetch can be used with other protocols. Obviously, if it is used with + other protocols than HTTP, the unique-id-format directive must not contain + HTTP parts. See: unique-id-format and unique-id-header + +url : string + This extracts the request's URL as presented in the request. A typical use is + with prefetch-capable caches, and with portals which need to aggregate + multiple information from databases and keep them in caches. With ACLs, using + "path" is preferred over using "url", because clients may send a full URL as + is normally done with proxies. The only real use is to match "*" which does + not match in "path", and for which there is already a predefined ACL. See + also "path" and "base". + + ACL derivatives : + url : exact string match + url_beg : prefix match + url_dir : subdir match + url_dom : domain match + url_end : suffix match + url_len : length match + url_reg : regex match + url_sub : substring match + +url_ip : ip + This extracts the IP address from the request's URL when the host part is + presented as an IP address. Its use is very limited. For instance, a + monitoring system might use this field as an alternative for the source IP in + order to test what path a given source address would follow, or to force an + entry in a table for a given source address. It may be used in combination + with 'http-request set-dst' to emulate the older 'option http_proxy'. + +url_port : integer + This extracts the port part from the request's URL. Note that if the port is + not specified in the request, port 80 is assumed.. + +urlp([<name>[,<delim>]]) : string +url_param([<name>[,<delim>]]) : string + This extracts the first occurrence of the parameter <name> in the query + string, which begins after either '?' or <delim>, and which ends before '&', + ';' or <delim>. The parameter name is case-sensitive. If no name is given, + any parameter will match, and the first one will be returned. The result is + a string corresponding to the value of the parameter <name> as presented in + the request (no URL decoding is performed). This can be used for session + stickiness based on a client ID, to extract an application cookie passed as a + URL parameter, or in ACLs to apply some checks. Note that the ACL version of + this fetch iterates over multiple parameters and will iteratively report all + parameters values if no name is given + + ACL derivatives : + urlp(<name>[,<delim>]) : exact string match + urlp_beg(<name>[,<delim>]) : prefix match + urlp_dir(<name>[,<delim>]) : subdir match + urlp_dom(<name>[,<delim>]) : domain match + urlp_end(<name>[,<delim>]) : suffix match + urlp_len(<name>[,<delim>]) : length match + urlp_reg(<name>[,<delim>]) : regex match + urlp_sub(<name>[,<delim>]) : substring match + + + Example : + # match http://example.com/foo?PHPSESSIONID=some_id + stick on urlp(PHPSESSIONID) + # match http://example.com/foo;JSESSIONID=some_id + stick on urlp(JSESSIONID,;) + +urlp_val([<name>[,<delim>]]) : integer + See "urlp" above. This one extracts the URL parameter <name> in the request + and converts it to an integer value. This can be used for session stickiness + based on a user ID for example, or with ACLs to match a page number or price. + +url32 : integer + This returns a 32-bit hash of the value obtained by concatenating the first + Host header and the whole URL including parameters (not only the path part of + the request, as in the "base32" fetch above). This is useful to track per-URL + activity. A shorter hash is stored, saving a lot of memory. The output type + is an unsigned integer. + +url32+src : binary + This returns the concatenation of the "url32" fetch and the "src" fetch. The + resulting type is of type binary, with a size of 8 or 20 bytes depending on + the source address family. This can be used to track per-IP, per-URL counters. + + +7.3.7. Fetching samples for developers +--------------------------------------- + +This set of sample fetch methods is reserved to developers and must never be +used on a production environment, except on developer demand, for debugging +purposes. Moreover, no special care will be taken on backwards compatibility. +There is no warranty the following sample fetches will never change, be renamed +or simply removed. So be really careful if you should use one of them. To avoid +any ambiguity, these sample fetches are placed in the dedicated scope "internal", +for instance "internal.strm.is_htx". + +internal.htx.data : integer + Returns the size in bytes used by data in the HTX message associated to a + channel. The channel is chosen depending on the sample direction. + +internal.htx.free : integer + Returns the free space (size - used) in bytes in the HTX message associated + to a channel. The channel is chosen depending on the sample direction. + +internal.htx.free_data : integer + Returns the free space for the data in bytes in the HTX message associated to + a channel. The channel is chosen depending on the sample direction. + +internal.htx.has_eom : boolean + Returns true if the HTX message associated to a channel contains the + end-of-message flag (EOM). Otherwise, it returns false. The channel is chosen + depending on the sample direction. + +internal.htx.nbblks : integer + Returns the number of blocks present in the HTX message associated to a + channel. The channel is chosen depending on the sample direction. + +internal.htx.size : integer + Returns the total size in bytes of the HTX message associated to a + channel. The channel is chosen depending on the sample direction. + +internal.htx.used : integer + Returns the total size used in bytes (data + metadata) in the HTX message + associated to a channel. The channel is chosen depending on the sample + direction. + +internal.htx_blk.size(<idx>) : integer + Returns the size of the block at the position <idx> in the HTX message + associated to a channel or 0 if it does not exist. The channel is chosen + depending on the sample direction. <idx> may be any positive integer or one + of the special value : + * head : The oldest inserted block + * tail : The newest inserted block + * first : The first block where to (re)start the analysis + +internal.htx_blk.type(<idx>) : string + Returns the type of the block at the position <idx> in the HTX message + associated to a channel or "HTX_BLK_UNUSED" if it does not exist. The channel + is chosen depending on the sample direction. <idx> may be any positive + integer or one of the special value : + * head : The oldest inserted block + * tail : The newest inserted block + * first : The first block where to (re)start the analysis + +internal.htx_blk.data(<idx>) : binary + Returns the value of the DATA block at the position <idx> in the HTX message + associated to a channel or an empty string if it does not exist or if it is + not a DATA block. The channel is chosen depending on the sample direction. + <idx> may be any positive integer or one of the special value : + + * head : The oldest inserted block + * tail : The newest inserted block + * first : The first block where to (re)start the analysis + +internal.htx_blk.hdrname(<idx>) : string + Returns the header name of the HEADER block at the position <idx> in the HTX + message associated to a channel or an empty string if it does not exist or if + it is not an HEADER block. The channel is chosen depending on the sample + direction. <idx> may be any positive integer or one of the special value : + + * head : The oldest inserted block + * tail : The newest inserted block + * first : The first block where to (re)start the analysis + +internal.htx_blk.hdrval(<idx>) : string + Returns the header value of the HEADER block at the position <idx> in the HTX + message associated to a channel or an empty string if it does not exist or if + it is not an HEADER block. The channel is chosen depending on the sample + direction. <idx> may be any positive integer or one of the special value : + + * head : The oldest inserted block + * tail : The newest inserted block + * first : The first block where to (re)start the analysis + +internal.htx_blk.start_line(<idx>) : string + Returns the value of the REQ_SL or RES_SL block at the position <idx> in the + HTX message associated to a channel or an empty string if it does not exist + or if it is not a SL block. The channel is chosen depending on the sample + direction. <idx> may be any positive integer or one of the special value : + + * head : The oldest inserted block + * tail : The newest inserted block + * first : The first block where to (re)start the analysis + +internal.strm.is_htx : boolean + Returns true if the current stream is an HTX stream. It means the data in the + channels buffers are stored using the internal HTX representation. Otherwise, + it returns false. + + +7.4. Pre-defined ACLs +--------------------- + +Some predefined ACLs are hard-coded so that they do not have to be declared in +every frontend which needs them. They all have their names in upper case in +order to avoid confusion. Their equivalence is provided below. + +ACL name Equivalent to Usage +---------------+----------------------------------+------------------------------------------------------ +FALSE always_false never match +HTTP req.proto_http match if request protocol is valid HTTP +HTTP_1.0 req.ver 1.0 match if HTTP request version is 1.0 +HTTP_1.1 req.ver 1.1 match if HTTP request version is 1.1 +HTTP_2.0 req.ver 2.0 match if HTTP request version is 2.0 +HTTP_CONTENT req.hdr_val(content-length) gt 0 match an existing content-length in the HTTP request +HTTP_URL_ABS url_reg ^[^/:]*:// match absolute URL with scheme +HTTP_URL_SLASH url_beg / match URL beginning with "/" +HTTP_URL_STAR url * match URL equal to "*" +LOCALHOST src 127.0.0.1/8 ::1 match connection from local host +METH_CONNECT method CONNECT match HTTP CONNECT method +METH_DELETE method DELETE match HTTP DELETE method +METH_GET method GET HEAD match HTTP GET or HEAD method +METH_HEAD method HEAD match HTTP HEAD method +METH_OPTIONS method OPTIONS match HTTP OPTIONS method +METH_POST method POST match HTTP POST method +METH_PUT method PUT match HTTP PUT method +METH_TRACE method TRACE match HTTP TRACE method +RDP_COOKIE req.rdp_cookie_cnt gt 0 match presence of an RDP cookie in the request buffer +REQ_CONTENT req.len gt 0 match data in the request buffer +TRUE always_true always match +WAIT_END wait_end wait for end of content analysis +---------------+----------------------------------+------------------------------------------------------ + + +8. Logging +---------- + +One of HAProxy's strong points certainly lies is its precise logs. It probably +provides the finest level of information available for such a product, which is +very important for troubleshooting complex environments. Standard information +provided in logs include client ports, TCP/HTTP state timers, precise session +state at termination and precise termination cause, information about decisions +to direct traffic to a server, and of course the ability to capture arbitrary +headers. + +In order to improve administrators reactivity, it offers a great transparency +about encountered problems, both internal and external, and it is possible to +send logs to different sources at the same time with different level filters : + + - global process-level logs (system errors, start/stop, etc..) + - per-instance system and internal errors (lack of resource, bugs, ...) + - per-instance external troubles (servers up/down, max connections) + - per-instance activity (client connections), either at the establishment or + at the termination. + - per-request control of log-level, e.g. + http-request set-log-level silent if sensitive_request + +The ability to distribute different levels of logs to different log servers +allow several production teams to interact and to fix their problems as soon +as possible. For example, the system team might monitor system-wide errors, +while the application team might be monitoring the up/down for their servers in +real time, and the security team might analyze the activity logs with one hour +delay. + + +8.1. Log levels +--------------- + +TCP and HTTP connections can be logged with information such as the date, time, +source IP address, destination address, connection duration, response times, +HTTP request, HTTP return code, number of bytes transmitted, conditions +in which the session ended, and even exchanged cookies values. For example +track a particular user's problems. All messages may be sent to up to two +syslog servers. Check the "log" keyword in section 4.2 for more information +about log facilities. + + +8.2. Log formats +---------------- + +HAProxy supports 5 log formats. Several fields are common between these formats +and will be detailed in the following sections. A few of them may vary +slightly with the configuration, due to indicators specific to certain +options. The supported formats are as follows : + + - the default format, which is very basic and very rarely used. It only + provides very basic information about the incoming connection at the moment + it is accepted : source IP:port, destination IP:port, and frontend-name. + This mode will eventually disappear so it will not be described to great + extents. + + - the TCP format, which is more advanced. This format is enabled when "option + tcplog" is set on the frontend. HAProxy will then usually wait for the + connection to terminate before logging. This format provides much richer + information, such as timers, connection counts, queue size, etc... This + format is recommended for pure TCP proxies. + + - the HTTP format, which is the most advanced for HTTP proxying. This format + is enabled when "option httplog" is set on the frontend. It provides the + same information as the TCP format with some HTTP-specific fields such as + the request, the status code, and captures of headers and cookies. This + format is recommended for HTTP proxies. + + - the CLF HTTP format, which is equivalent to the HTTP format, but with the + fields arranged in the same order as the CLF format. In this mode, all + timers, captures, flags, etc... appear one per field after the end of the + common fields, in the same order they appear in the standard HTTP format. + + - the custom log format, allows you to make your own log line. + +Next sections will go deeper into details for each of these formats. Format +specification will be performed on a "field" basis. Unless stated otherwise, a +field is a portion of text delimited by any number of spaces. Since syslog +servers are susceptible of inserting fields at the beginning of a line, it is +always assumed that the first field is the one containing the process name and +identifier. + +Note : Since log lines may be quite long, the log examples in sections below + might be broken into multiple lines. The example log lines will be + prefixed with 3 closing angle brackets ('>>>') and each time a log is + broken into multiple lines, each non-final line will end with a + backslash ('\') and the next line will start indented by two characters. + + +8.2.1. Default log format +------------------------- + +This format is used when no specific option is set. The log is emitted as soon +as the connection is accepted. One should note that this currently is the only +format which logs the request's destination IP and ports. + + Example : + listen www + mode http + log global + server srv1 127.0.0.1:8000 + + >>> Feb 6 12:12:09 localhost \ + haproxy[14385]: Connect from 10.0.1.2:33312 to 10.0.3.31:8012 \ + (www/HTTP) + + Field Format Extract from the example above + 1 process_name '[' pid ']:' haproxy[14385]: + 2 'Connect from' Connect from + 3 source_ip ':' source_port 10.0.1.2:33312 + 4 'to' to + 5 destination_ip ':' destination_port 10.0.3.31:8012 + 6 '(' frontend_name '/' mode ')' (www/HTTP) + +Detailed fields description : + - "source_ip" is the IP address of the client which initiated the connection. + - "source_port" is the TCP port of the client which initiated the connection. + - "destination_ip" is the IP address the client connected to. + - "destination_port" is the TCP port the client connected to. + - "frontend_name" is the name of the frontend (or listener) which received + and processed the connection. + - "mode is the mode the frontend is operating (TCP or HTTP). + +In case of a UNIX socket, the source and destination addresses are marked as +"unix:" and the ports reflect the internal ID of the socket which accepted the +connection (the same ID as reported in the stats). + +It is advised not to use this deprecated format for newer installations as it +will eventually disappear. + + +8.2.2. TCP log format +--------------------- + +The TCP format is used when "option tcplog" is specified in the frontend, and +is the recommended format for pure TCP proxies. It provides a lot of precious +information for troubleshooting. Since this format includes timers and byte +counts, the log is normally emitted at the end of the session. It can be +emitted earlier if "option logasap" is specified, which makes sense in most +environments with long sessions such as remote terminals. Sessions which match +the "monitor" rules are never logged. It is also possible not to emit logs for +sessions for which no data were exchanged between the client and the server, by +specifying "option dontlognull" in the frontend. Successful connections will +not be logged if "option dontlog-normal" is specified in the frontend. + +The TCP log format is internally declared as a custom log format based on the +exact following string, which may also be used as a basis to extend the format +if required. Refer to section 8.2.6 "Custom log format" to see how to use this: + + # strict equivalent of "option tcplog" + log-format "%ci:%cp [%t] %ft %b/%s %Tw/%Tc/%Tt %B %ts \ + %ac/%fc/%bc/%sc/%rc %sq/%bq" + +A few fields may slightly vary depending on some configuration options, those +are marked with a star ('*') after the field name below. + + Example : + frontend fnt + mode tcp + option tcplog + log global + default_backend bck + + backend bck + server srv1 127.0.0.1:8000 + + >>> Feb 6 12:12:56 localhost \ + haproxy[14387]: 10.0.1.2:33313 [06/Feb/2009:12:12:51.443] fnt \ + bck/srv1 0/0/5007 212 -- 0/0/0/0/3 0/0 + + Field Format Extract from the example above + 1 process_name '[' pid ']:' haproxy[14387]: + 2 client_ip ':' client_port 10.0.1.2:33313 + 3 '[' accept_date ']' [06/Feb/2009:12:12:51.443] + 4 frontend_name fnt + 5 backend_name '/' server_name bck/srv1 + 6 Tw '/' Tc '/' Tt* 0/0/5007 + 7 bytes_read* 212 + 8 termination_state -- + 9 actconn '/' feconn '/' beconn '/' srv_conn '/' retries* 0/0/0/0/3 + 10 srv_queue '/' backend_queue 0/0 + +Detailed fields description : + - "client_ip" is the IP address of the client which initiated the TCP + connection to HAProxy. If the connection was accepted on a UNIX socket + instead, the IP address would be replaced with the word "unix". Note that + when the connection is accepted on a socket configured with "accept-proxy" + and the PROXY protocol is correctly used, or with a "accept-netscaler-cip" + and the NetScaler Client IP insertion protocol is correctly used, then the + logs will reflect the forwarded connection's information. + + - "client_port" is the TCP port of the client which initiated the connection. + If the connection was accepted on a UNIX socket instead, the port would be + replaced with the ID of the accepting socket, which is also reported in the + stats interface. + + - "accept_date" is the exact date when the connection was received by HAProxy + (which might be very slightly different from the date observed on the + network if there was some queuing in the system's backlog). This is usually + the same date which may appear in any upstream firewall's log. When used in + HTTP mode, the accept_date field will be reset to the first moment the + connection is ready to receive a new request (end of previous response for + HTTP/1, immediately after previous request for HTTP/2). + + - "frontend_name" is the name of the frontend (or listener) which received + and processed the connection. + + - "backend_name" is the name of the backend (or listener) which was selected + to manage the connection to the server. This will be the same as the + frontend if no switching rule has been applied, which is common for TCP + applications. + + - "server_name" is the name of the last server to which the connection was + sent, which might differ from the first one if there were connection errors + and a redispatch occurred. Note that this server belongs to the backend + which processed the request. If the connection was aborted before reaching + a server, "<NOSRV>" is indicated instead of a server name. + + - "Tw" is the total time in milliseconds spent waiting in the various queues. + It can be "-1" if the connection was aborted before reaching the queue. + See "Timers" below for more details. + + - "Tc" is the total time in milliseconds spent waiting for the connection to + establish to the final server, including retries. It can be "-1" if the + connection was aborted before a connection could be established. See + "Timers" below for more details. + + - "Tt" is the total time in milliseconds elapsed between the accept and the + last close. It covers all possible processing. There is one exception, if + "option logasap" was specified, then the time counting stops at the moment + the log is emitted. In this case, a '+' sign is prepended before the value, + indicating that the final one will be larger. See "Timers" below for more + details. + + - "bytes_read" is the total number of bytes transmitted from the server to + the client when the log is emitted. If "option logasap" is specified, the + this value will be prefixed with a '+' sign indicating that the final one + may be larger. Please note that this value is a 64-bit counter, so log + analysis tools must be able to handle it without overflowing. + + - "termination_state" is the condition the session was in when the session + ended. This indicates the session state, which side caused the end of + session to happen, and for what reason (timeout, error, ...). The normal + flags should be "--", indicating the session was closed by either end with + no data remaining in buffers. See below "Session state at disconnection" + for more details. + + - "actconn" is the total number of concurrent connections on the process when + the session was logged. It is useful to detect when some per-process system + limits have been reached. For instance, if actconn is close to 512 when + multiple connection errors occur, chances are high that the system limits + the process to use a maximum of 1024 file descriptors and that all of them + are used. See section 3 "Global parameters" to find how to tune the system. + + - "feconn" is the total number of concurrent connections on the frontend when + the session was logged. It is useful to estimate the amount of resource + required to sustain high loads, and to detect when the frontend's "maxconn" + has been reached. Most often when this value increases by huge jumps, it is + because there is congestion on the backend servers, but sometimes it can be + caused by a denial of service attack. + + - "beconn" is the total number of concurrent connections handled by the + backend when the session was logged. It includes the total number of + concurrent connections active on servers as well as the number of + connections pending in queues. It is useful to estimate the amount of + additional servers needed to support high loads for a given application. + Most often when this value increases by huge jumps, it is because there is + congestion on the backend servers, but sometimes it can be caused by a + denial of service attack. + + - "srv_conn" is the total number of concurrent connections still active on + the server when the session was logged. It can never exceed the server's + configured "maxconn" parameter. If this value is very often close or equal + to the server's "maxconn", it means that traffic regulation is involved a + lot, meaning that either the server's maxconn value is too low, or that + there aren't enough servers to process the load with an optimal response + time. When only one of the server's "srv_conn" is high, it usually means + that this server has some trouble causing the connections to take longer to + be processed than on other servers. + + - "retries" is the number of connection retries experienced by this session + when trying to connect to the server. It must normally be zero, unless a + server is being stopped at the same moment the connection was attempted. + Frequent retries generally indicate either a network problem between + HAProxy and the server, or a misconfigured system backlog on the server + preventing new connections from being queued. This field may optionally be + prefixed with a '+' sign, indicating that the session has experienced a + redispatch after the maximal retry count has been reached on the initial + server. In this case, the server name appearing in the log is the one the + connection was redispatched to, and not the first one, though both may + sometimes be the same in case of hashing for instance. So as a general rule + of thumb, when a '+' is present in front of the retry count, this count + should not be attributed to the logged server. + + - "srv_queue" is the total number of requests which were processed before + this one in the server queue. It is zero when the request has not gone + through the server queue. It makes it possible to estimate the approximate + server's response time by dividing the time spent in queue by the number of + requests in the queue. It is worth noting that if a session experiences a + redispatch and passes through two server queues, their positions will be + cumulative. A request should not pass through both the server queue and the + backend queue unless a redispatch occurs. + + - "backend_queue" is the total number of requests which were processed before + this one in the backend's global queue. It is zero when the request has not + gone through the global queue. It makes it possible to estimate the average + queue length, which easily translates into a number of missing servers when + divided by a server's "maxconn" parameter. It is worth noting that if a + session experiences a redispatch, it may pass twice in the backend's queue, + and then both positions will be cumulative. A request should not pass + through both the server queue and the backend queue unless a redispatch + occurs. + + +8.2.3. HTTP log format +---------------------- + +The HTTP format is the most complete and the best suited for HTTP proxies. It +is enabled by when "option httplog" is specified in the frontend. It provides +the same level of information as the TCP format with additional features which +are specific to the HTTP protocol. Just like the TCP format, the log is usually +emitted at the end of the session, unless "option logasap" is specified, which +generally only makes sense for download sites. A session which matches the +"monitor" rules will never logged. It is also possible not to log sessions for +which no data were sent by the client by specifying "option dontlognull" in the +frontend. Successful connections will not be logged if "option dontlog-normal" +is specified in the frontend. + +The HTTP log format is internally declared as a custom log format based on the +exact following string, which may also be used as a basis to extend the format +if required. Refer to section 8.2.6 "Custom log format" to see how to use this: + + # strict equivalent of "option httplog" + log-format "%ci:%cp [%tr] %ft %b/%s %TR/%Tw/%Tc/%Tr/%Ta %ST %B %CC \ + %CS %tsc %ac/%fc/%bc/%sc/%rc %sq/%bq %hr %hs %{+Q}r" + +And the CLF log format is internally declared as a custom log format based on +this exact string: + + # strict equivalent of "option httplog clf" + log-format "%{+Q}o %{-Q}ci - - [%trg] %r %ST %B \"\" \"\" %cp \ + %ms %ft %b %s %TR %Tw %Tc %Tr %Ta %tsc %ac %fc \ + %bc %sc %rc %sq %bq %CC %CS %hrl %hsl" + +Most fields are shared with the TCP log, some being different. A few fields may +slightly vary depending on some configuration options. Those ones are marked +with a star ('*') after the field name below. + + Example : + frontend http-in + mode http + option httplog + log global + default_backend bck + + backend static + server srv1 127.0.0.1:8000 + + >>> Feb 6 12:14:14 localhost \ + haproxy[14389]: 10.0.1.2:33317 [06/Feb/2009:12:14:14.655] http-in \ + static/srv1 10/0/30/69/109 200 2750 - - ---- 1/1/1/1/0 0/0 {1wt.eu} \ + {} "GET /index.html HTTP/1.1" + + Field Format Extract from the example above + 1 process_name '[' pid ']:' haproxy[14389]: + 2 client_ip ':' client_port 10.0.1.2:33317 + 3 '[' request_date ']' [06/Feb/2009:12:14:14.655] + 4 frontend_name http-in + 5 backend_name '/' server_name static/srv1 + 6 TR '/' Tw '/' Tc '/' Tr '/' Ta* 10/0/30/69/109 + 7 status_code 200 + 8 bytes_read* 2750 + 9 captured_request_cookie - + 10 captured_response_cookie - + 11 termination_state ---- + 12 actconn '/' feconn '/' beconn '/' srv_conn '/' retries* 1/1/1/1/0 + 13 srv_queue '/' backend_queue 0/0 + 14 '{' captured_request_headers* '}' {haproxy.1wt.eu} + 15 '{' captured_response_headers* '}' {} + 16 '"' http_request '"' "GET /index.html HTTP/1.1" + +Detailed fields description : + - "client_ip" is the IP address of the client which initiated the TCP + connection to HAProxy. If the connection was accepted on a UNIX socket + instead, the IP address would be replaced with the word "unix". Note that + when the connection is accepted on a socket configured with "accept-proxy" + and the PROXY protocol is correctly used, or with a "accept-netscaler-cip" + and the NetScaler Client IP insertion protocol is correctly used, then the + logs will reflect the forwarded connection's information. + + - "client_port" is the TCP port of the client which initiated the connection. + If the connection was accepted on a UNIX socket instead, the port would be + replaced with the ID of the accepting socket, which is also reported in the + stats interface. + + - "request_date" is the exact date when the first byte of the HTTP request + was received by HAProxy (log field %tr). + + - "frontend_name" is the name of the frontend (or listener) which received + and processed the connection. + + - "backend_name" is the name of the backend (or listener) which was selected + to manage the connection to the server. This will be the same as the + frontend if no switching rule has been applied. + + - "server_name" is the name of the last server to which the connection was + sent, which might differ from the first one if there were connection errors + and a redispatch occurred. Note that this server belongs to the backend + which processed the request. If the request was aborted before reaching a + server, "<NOSRV>" is indicated instead of a server name. If the request was + intercepted by the stats subsystem, "<STATS>" is indicated instead. + + - "TR" is the total time in milliseconds spent waiting for a full HTTP + request from the client (not counting body) after the first byte was + received. It can be "-1" if the connection was aborted before a complete + request could be received or a bad request was received. It should + always be very small because a request generally fits in one single packet. + Large times here generally indicate network issues between the client and + HAProxy or requests being typed by hand. See section 8.4 "Timing Events" + for more details. + + - "Tw" is the total time in milliseconds spent waiting in the various queues. + It can be "-1" if the connection was aborted before reaching the queue. + See section 8.4 "Timing Events" for more details. + + - "Tc" is the total time in milliseconds spent waiting for the connection to + establish to the final server, including retries. It can be "-1" if the + request was aborted before a connection could be established. See section + 8.4 "Timing Events" for more details. + + - "Tr" is the total time in milliseconds spent waiting for the server to send + a full HTTP response, not counting data. It can be "-1" if the request was + aborted before a complete response could be received. It generally matches + the server's processing time for the request, though it may be altered by + the amount of data sent by the client to the server. Large times here on + "GET" requests generally indicate an overloaded server. See section 8.4 + "Timing Events" for more details. + + - "Ta" is the time the request remained active in HAProxy, which is the total + time in milliseconds elapsed between the first byte of the request was + received and the last byte of response was sent. It covers all possible + processing except the handshake (see Th) and idle time (see Ti). There is + one exception, if "option logasap" was specified, then the time counting + stops at the moment the log is emitted. In this case, a '+' sign is + prepended before the value, indicating that the final one will be larger. + See section 8.4 "Timing Events" for more details. + + - "status_code" is the HTTP status code returned to the client. This status + is generally set by the server, but it might also be set by HAProxy when + the server cannot be reached or when its response is blocked by HAProxy. + + - "bytes_read" is the total number of bytes transmitted to the client when + the log is emitted. This does include HTTP headers. If "option logasap" is + specified, this value will be prefixed with a '+' sign indicating that + the final one may be larger. Please note that this value is a 64-bit + counter, so log analysis tools must be able to handle it without + overflowing. + + - "captured_request_cookie" is an optional "name=value" entry indicating that + the client had this cookie in the request. The cookie name and its maximum + length are defined by the "capture cookie" statement in the frontend + configuration. The field is a single dash ('-') when the option is not + set. Only one cookie may be captured, it is generally used to track session + ID exchanges between a client and a server to detect session crossing + between clients due to application bugs. For more details, please consult + the section "Capturing HTTP headers and cookies" below. + + - "captured_response_cookie" is an optional "name=value" entry indicating + that the server has returned a cookie with its response. The cookie name + and its maximum length are defined by the "capture cookie" statement in the + frontend configuration. The field is a single dash ('-') when the option is + not set. Only one cookie may be captured, it is generally used to track + session ID exchanges between a client and a server to detect session + crossing between clients due to application bugs. For more details, please + consult the section "Capturing HTTP headers and cookies" below. + + - "termination_state" is the condition the session was in when the session + ended. This indicates the session state, which side caused the end of + session to happen, for what reason (timeout, error, ...), just like in TCP + logs, and information about persistence operations on cookies in the last + two characters. The normal flags should begin with "--", indicating the + session was closed by either end with no data remaining in buffers. See + below "Session state at disconnection" for more details. + + - "actconn" is the total number of concurrent connections on the process when + the session was logged. It is useful to detect when some per-process system + limits have been reached. For instance, if actconn is close to 512 or 1024 + when multiple connection errors occur, chances are high that the system + limits the process to use a maximum of 1024 file descriptors and that all + of them are used. See section 3 "Global parameters" to find how to tune the + system. + + - "feconn" is the total number of concurrent connections on the frontend when + the session was logged. It is useful to estimate the amount of resource + required to sustain high loads, and to detect when the frontend's "maxconn" + has been reached. Most often when this value increases by huge jumps, it is + because there is congestion on the backend servers, but sometimes it can be + caused by a denial of service attack. + + - "beconn" is the total number of concurrent connections handled by the + backend when the session was logged. It includes the total number of + concurrent connections active on servers as well as the number of + connections pending in queues. It is useful to estimate the amount of + additional servers needed to support high loads for a given application. + Most often when this value increases by huge jumps, it is because there is + congestion on the backend servers, but sometimes it can be caused by a + denial of service attack. + + - "srv_conn" is the total number of concurrent connections still active on + the server when the session was logged. It can never exceed the server's + configured "maxconn" parameter. If this value is very often close or equal + to the server's "maxconn", it means that traffic regulation is involved a + lot, meaning that either the server's maxconn value is too low, or that + there aren't enough servers to process the load with an optimal response + time. When only one of the server's "srv_conn" is high, it usually means + that this server has some trouble causing the requests to take longer to be + processed than on other servers. + + - "retries" is the number of connection retries experienced by this session + when trying to connect to the server. It must normally be zero, unless a + server is being stopped at the same moment the connection was attempted. + Frequent retries generally indicate either a network problem between + HAProxy and the server, or a misconfigured system backlog on the server + preventing new connections from being queued. This field may optionally be + prefixed with a '+' sign, indicating that the session has experienced a + redispatch after the maximal retry count has been reached on the initial + server. In this case, the server name appearing in the log is the one the + connection was redispatched to, and not the first one, though both may + sometimes be the same in case of hashing for instance. So as a general rule + of thumb, when a '+' is present in front of the retry count, this count + should not be attributed to the logged server. + + - "srv_queue" is the total number of requests which were processed before + this one in the server queue. It is zero when the request has not gone + through the server queue. It makes it possible to estimate the approximate + server's response time by dividing the time spent in queue by the number of + requests in the queue. It is worth noting that if a session experiences a + redispatch and passes through two server queues, their positions will be + cumulative. A request should not pass through both the server queue and the + backend queue unless a redispatch occurs. + + - "backend_queue" is the total number of requests which were processed before + this one in the backend's global queue. It is zero when the request has not + gone through the global queue. It makes it possible to estimate the average + queue length, which easily translates into a number of missing servers when + divided by a server's "maxconn" parameter. It is worth noting that if a + session experiences a redispatch, it may pass twice in the backend's queue, + and then both positions will be cumulative. A request should not pass + through both the server queue and the backend queue unless a redispatch + occurs. + + - "captured_request_headers" is a list of headers captured in the request due + to the presence of the "capture request header" statement in the frontend. + Multiple headers can be captured, they will be delimited by a vertical bar + ('|'). When no capture is enabled, the braces do not appear, causing a + shift of remaining fields. It is important to note that this field may + contain spaces, and that using it requires a smarter log parser than when + it's not used. Please consult the section "Capturing HTTP headers and + cookies" below for more details. + + - "captured_response_headers" is a list of headers captured in the response + due to the presence of the "capture response header" statement in the + frontend. Multiple headers can be captured, they will be delimited by a + vertical bar ('|'). When no capture is enabled, the braces do not appear, + causing a shift of remaining fields. It is important to note that this + field may contain spaces, and that using it requires a smarter log parser + than when it's not used. Please consult the section "Capturing HTTP headers + and cookies" below for more details. + + - "http_request" is the complete HTTP request line, including the method, + request and HTTP version string. Non-printable characters are encoded (see + below the section "Non-printable characters"). This is always the last + field, and it is always delimited by quotes and is the only one which can + contain quotes. If new fields are added to the log format, they will be + added before this field. This field might be truncated if the request is + huge and does not fit in the standard syslog buffer (1024 characters). This + is the reason why this field must always remain the last one. + + +8.2.4. HTTPS log format +---------------------- + +The HTTPS format is the best suited for HTTP over SSL connections. It is an +extension of the HTTP format (see section 8.2.3) to which SSL related +information are added. It is enabled when "option httpslog" is specified in the +frontend. Just like the TCP and HTTP formats, the log is usually emitted at the +end of the session, unless "option logasap" is specified. A session which +matches the "monitor" rules will never logged. It is also possible not to log +sessions for which no data were sent by the client by specifying "option +dontlognull" in the frontend. Successful connections will not be logged if +"option dontlog-normal" is specified in the frontend. + +The HTTPS log format is internally declared as a custom log format based on the +exact following string, which may also be used as a basis to extend the format +if required. Refer to section 8.2.6 "Custom log format" to see how to use this: + + # strict equivalent of "option httpslog" + log-format "%ci:%cp [%tr] %ft %b/%s %TR/%Tw/%Tc/%Tr/%Ta %ST %B %CC \ + %CS %tsc %ac/%fc/%bc/%sc/%rc %sq/%bq %hr %hs %{+Q}r \ + %[fc_err]/%[ssl_fc_err,hex]/%[ssl_c_err]/\ + %[ssl_c_ca_err]/%[ssl_fc_is_resumed] %[ssl_fc_sni]/%sslv/%sslc" + +This format is basically the HTTP one (see section 8.2.3) with new fields +appended to it. The new fields (lines 17 and 18) will be detailed here. For the +HTTP ones, refer to the HTTP section. + + Example : + frontend https-in + mode http + option httpslog + log global + bind *:443 ssl crt mycerts/srv.pem ... + default_backend bck + + backend static + server srv1 127.0.0.1:8000 ssl crt mycerts/clt.pem ... + + >>> Feb 6 12:14:14 localhost \ + haproxy[14389]: 10.0.1.2:33317 [06/Feb/2009:12:14:14.655] https-in \ + static/srv1 10/0/30/69/109 200 2750 - - ---- 1/1/1/1/0 0/0 {1wt.eu} \ + {} "GET /index.html HTTP/1.1" 0/0/0/0/0 \ + 1wt.eu/TLSv1.3/TLS_AES_256_GCM_SHA384 + + Field Format Extract from the example above + 1 process_name '[' pid ']:' haproxy[14389]: + 2 client_ip ':' client_port 10.0.1.2:33317 + 3 '[' request_date ']' [06/Feb/2009:12:14:14.655] + 4 frontend_name https-in + 5 backend_name '/' server_name static/srv1 + 6 TR '/' Tw '/' Tc '/' Tr '/' Ta* 10/0/30/69/109 + 7 status_code 200 + 8 bytes_read* 2750 + 9 captured_request_cookie - + 10 captured_response_cookie - + 11 termination_state ---- + 12 actconn '/' feconn '/' beconn '/' srv_conn '/' retries* 1/1/1/1/0 + 13 srv_queue '/' backend_queue 0/0 + 14 '{' captured_request_headers* '}' {haproxy.1wt.eu} + 15 '{' captured_response_headers* '}' {} + 16 '"' http_request '"' "GET /index.html HTTP/1.1" + 17 fc_err '/' ssl_fc_err '/' ssl_c_err + '/' ssl_c_ca_err '/' ssl_fc_is_resumed 0/0/0/0/0 + 18 ssl_fc_sni '/' ssl_version + '/' ssl_ciphers 1wt.eu/TLSv1.3/TLS_AES_256_GCM_SHA384 + +Detailed fields description : + - "fc_err" is the status of the connection on the frontend's side. It + corresponds to the "fc_err" sample fetch. See the "fc_err" and "fc_err_str" + sample fetch functions for more information. + + - "ssl_fc_err" is the last error of the first SSL error stack that was + raised on the connection from the frontend's perspective. It might be used + to detect SSL handshake errors for instance. It will be 0 if everything + went well. See the "ssl_fc_err" sample fetch's description for more + information. + + - "ssl_c_err" is the status of the client's certificate verification process. + The handshake might be successful while having a non-null verification + error code if it is an ignored one. See the "ssl_c_err" sample fetch and + the "crt-ignore-err" option. + + - "ssl_c_ca_err" is the status of the client's certificate chain verification + process. The handshake might be successful while having a non-null + verification error code if it is an ignored one. See the "ssl_c_ca_err" + sample fetch and the "ca-ignore-err" option. + + - "ssl_fc_is_resumed" is true if the incoming TLS session was resumed with + the stateful cache or a stateless ticket. Don't forgot that a TLS session + can be shared by multiple requests. + + - "ssl_fc_sni" is the SNI (Server Name Indication) presented by the client + to select the certificate to be used. It usually matches the host name for + the first request of a connection. An absence of this field may indicate + that the SNI was not sent by the client, and will lead haproxy to use the + default certificate, or to reject the connection in case of strict-sni. + + - "ssl_version" is the SSL version of the frontend. + + - "ssl_ciphers" is the SSL cipher used for the connection. + + +8.2.5. Error log format +----------------------- + +When an incoming connection fails due to an SSL handshake or an invalid PROXY +protocol header, HAProxy will log the event using a shorter, fixed line format, +unless a dedicated error log format is defined through an "error-log-format" +line. By default, logs are emitted at the LOG_INFO level, unless the option +"log-separate-errors" is set in the backend, in which case the LOG_ERR level +will be used. Connections on which no data are exchanged (e.g. probes) are not +logged if the "dontlognull" option is set. + +The default format looks like this : + + >>> Dec 3 18:27:14 localhost \ + haproxy[6103]: 127.0.0.1:56059 [03/Dec/2012:17:35:10.380] frt/f1: \ + Connection error during SSL handshake + + Field Format Extract from the example above + 1 process_name '[' pid ']:' haproxy[6103]: + 2 client_ip ':' client_port 127.0.0.1:56059 + 3 '[' accept_date ']' [03/Dec/2012:17:35:10.380] + 4 frontend_name "/" bind_name ":" frt/f1: + 5 message Connection error during SSL handshake + +These fields just provide minimal information to help debugging connection +failures. + +By using the "error-log-format" directive, the legacy log format described +above will not be used anymore, and all error log lines will follow the +defined format. + +An example of reasonably complete error-log-format follows, it will report the +source address and port, the connection accept() date, the frontend name, the +number of active connections on the process and on thit frontend, haproxy's +internal error identifier on the front connection, the hexadecimal OpenSSL +error number (that can be copy-pasted to "openssl errstr" for full decoding), +the client certificate extraction status (0 indicates no error), the client +certificate validation status using the CA (0 indicates no error), a boolean +indicating if the connection is new or was resumed, the optional server name +indication (SNI) provided by the client, the SSL version name and the SSL +ciphers used on the connection, if any. Note that backend connection errors +are never reported here since in order for a backend connection to fail, it +would have passed through a successful stream, hence will be available as +regular traffic log (see option httplog or option httpslog). + + # detailed frontend connection error log + error-log-format "%ci:%cp [%tr] %ft %ac/%fc %[fc_err]/\ + %[ssl_fc_err,hex]/%[ssl_c_err]/%[ssl_c_ca_err]/%[ssl_fc_is_resumed] \ + %[ssl_fc_sni]/%sslv/%sslc" + + +8.2.6. Custom log format +------------------------ + +When the default log formats are not sufficient, it is possible to define new +ones in very fine details. As creating a log-format from scratch is not always +a trivial task, it is strongly recommended to first have a look at the existing +formats ("option tcplog", "option httplog", "option httpslog"), pick the one +looking the closest to the expectation, copy its "log-format" equivalent string +and adjust it. + +HAProxy understands some log format variables. % precedes log format variables. +Variables can take arguments using braces ('{}'), and multiple arguments are +separated by commas within the braces. Flags may be added or removed by +prefixing them with a '+' or '-' sign. + +Special variable "%o" may be used to propagate its flags to all other +variables on the same format string. This is particularly handy with quoted +("Q") and escaped ("E") string formats. + +If a variable is named between square brackets ('[' .. ']') then it is used +as a sample expression rule (see section 7.3). This it useful to add some +less common information such as the client's SSL certificate's DN, or to log +the key that would be used to store an entry into a stick table. + +Note: spaces must be escaped. In configuration directives "log-format", +"log-format-sd" and "unique-id-format", spaces are considered as +delimiters and are merged. In order to emit a verbatim '%', it must be +preceded by another '%' resulting in '%%'. + +Note: when using the RFC5424 syslog message format, the characters '"', +'\' and ']' inside PARAM-VALUE should be escaped with '\' as prefix (see +https://tools.ietf.org/html/rfc5424#section-6.3.3 for more details). In +such cases, the use of the flag "E" should be considered. + +Flags are : + * Q: quote a string + * X: hexadecimal representation (IPs, Ports, %Ts, %rt, %pid) + * E: escape characters '"', '\' and ']' in a string with '\' as prefix + (intended purpose is for the RFC5424 structured-data log formats) + + Example: + + log-format %T\ %t\ Some\ Text + log-format %{+Q}o\ %t\ %s\ %{-Q}r + + log-format-sd %{+Q,+E}o\ [exampleSDID@1234\ header=%[capture.req.hdr(0)]] + +Please refer to the table below for currently defined variables : + + +---+------+-----------------------------------------------+-------------+ + | R | var | field name (8.2.2 and 8.2.3 for description) | type | + +---+------+-----------------------------------------------+-------------+ + | | %o | special variable, apply flags on all next var | | + +---+------+-----------------------------------------------+-------------+ + | | %B | bytes_read (from server to client) | numeric | + | H | %CC | captured_request_cookie | string | + | H | %CS | captured_response_cookie | string | + | | %H | hostname | string | + | H | %HM | HTTP method (ex: POST) | string | + | H | %HP | HTTP request URI without query string | string | + | H | %HPO | HTTP path only (without host nor query string)| string | + | H | %HQ | HTTP request URI query string (ex: ?bar=baz) | string | + | H | %HU | HTTP request URI (ex: /foo?bar=baz) | string | + | H | %HV | HTTP version (ex: HTTP/1.0) | string | + | | %ID | unique-id | string | + | | %ST | status_code | numeric | + | | %T | gmt_date_time | date | + | H | %Ta | Active time of the request (from TR to end) | numeric | + | | %Tc | Tc | numeric | + | | %Td | Td = Tt - (Tq + Tw + Tc + Tr) | numeric | + | | %Tl | local_date_time | date | + | | %Th | connection handshake time (SSL, PROXY proto) | numeric | + | H | %Ti | idle time before the HTTP request | numeric | + | H | %Tq | Th + Ti + TR | numeric | + | H | %TR | time to receive the full request from 1st byte| numeric | + | H | %Tr | Tr (response time) | numeric | + | | %Ts | timestamp | numeric | + | | %Tt | Tt | numeric | + | | %Tu | Tu | numeric | + | | %Tw | Tw | numeric | + | | %U | bytes_uploaded (from client to server) | numeric | + | | %ac | actconn | numeric | + | | %b | backend_name | string | + | | %bc | beconn (backend concurrent connections) | numeric | + | | %bi | backend_source_ip (connecting address) | IP | + | | %bp | backend_source_port (connecting address) | numeric | + | | %bq | backend_queue | numeric | + | | %ci | client_ip (accepted address) | IP | + | | %cp | client_port (accepted address) | numeric | + | | %f | frontend_name | string | + | | %fc | feconn (frontend concurrent connections) | numeric | + | | %fi | frontend_ip (accepting address) | IP | + | | %fp | frontend_port (accepting address) | numeric | + | | %ft | frontend_name_transport ('~' suffix for SSL) | string | + | | %lc | frontend_log_counter | numeric | + | | %hr | captured_request_headers default style | string | + | | %hrl | captured_request_headers CLF style | string list | + | | %hs | captured_response_headers default style | string | + | | %hsl | captured_response_headers CLF style | string list | + | | %ms | accept date milliseconds (left-padded with 0) | numeric | + | | %pid | PID | numeric | + | H | %r | http_request | string | + | | %rc | retries | numeric | + | | %rt | request_counter (HTTP req or TCP session) | numeric | + | | %s | server_name | string | + | | %sc | srv_conn (server concurrent connections) | numeric | + | | %si | server_IP (target address) | IP | + | | %sp | server_port (target address) | numeric | + | | %sq | srv_queue | numeric | + | S | %sslc| ssl_ciphers (ex: AES-SHA) | string | + | S | %sslv| ssl_version (ex: TLSv1) | string | + | | %t | date_time (with millisecond resolution) | date | + | H | %tr | date_time of HTTP request | date | + | H | %trg | gmt_date_time of start of HTTP request | date | + | H | %trl | local_date_time of start of HTTP request | date | + | | %ts | termination_state | string | + | H | %tsc | termination_state with cookie status | string | + +---+------+-----------------------------------------------+-------------+ + + R = Restrictions : H = mode http only ; S = SSL only + + +8.3. Advanced logging options +----------------------------- + +Some advanced logging options are often looked for but are not easy to find out +just by looking at the various options. Here is an entry point for the few +options which can enable better logging. Please refer to the keywords reference +for more information about their usage. + + +8.3.1. Disabling logging of external tests +------------------------------------------ + +It is quite common to have some monitoring tools perform health checks on +HAProxy. Sometimes it will be a layer 3 load-balancer such as LVS or any +commercial load-balancer, and sometimes it will simply be a more complete +monitoring system such as Nagios. When the tests are very frequent, users often +ask how to disable logging for those checks. There are three possibilities : + + - if connections come from everywhere and are just TCP probes, it is often + desired to simply disable logging of connections without data exchange, by + setting "option dontlognull" in the frontend. It also disables logging of + port scans, which may or may not be desired. + + - it is possible to use the "http-request set-log-level silent" action using + a variety of conditions (source networks, paths, user-agents, etc). + + - if the tests are performed on a known URI, use "monitor-uri" to declare + this URI as dedicated to monitoring. Any host sending this request will + only get the result of a health-check, and the request will not be logged. + + +8.3.2. Logging before waiting for the session to terminate +---------------------------------------------------------- + +The problem with logging at end of connection is that you have no clue about +what is happening during very long sessions, such as remote terminal sessions +or large file downloads. This problem can be worked around by specifying +"option logasap" in the frontend. HAProxy will then log as soon as possible, +just before data transfer begins. This means that in case of TCP, it will still +log the connection status to the server, and in case of HTTP, it will log just +after processing the server headers. In this case, the number of bytes reported +is the number of header bytes sent to the client. In order to avoid confusion +with normal logs, the total time field and the number of bytes are prefixed +with a '+' sign which means that real numbers are certainly larger. + + +8.3.3. Raising log level upon errors +------------------------------------ + +Sometimes it is more convenient to separate normal traffic from errors logs, +for instance in order to ease error monitoring from log files. When the option +"log-separate-errors" is used, connections which experience errors, timeouts, +retries, redispatches or HTTP status codes 5xx will see their syslog level +raised from "info" to "err". This will help a syslog daemon store the log in +a separate file. It is very important to keep the errors in the normal traffic +file too, so that log ordering is not altered. You should also be careful if +you already have configured your syslog daemon to store all logs higher than +"notice" in an "admin" file, because the "err" level is higher than "notice". + + +8.3.4. Disabling logging of successful connections +-------------------------------------------------- + +Although this may sound strange at first, some large sites have to deal with +multiple thousands of logs per second and are experiencing difficulties keeping +them intact for a long time or detecting errors within them. If the option +"dontlog-normal" is set on the frontend, all normal connections will not be +logged. In this regard, a normal connection is defined as one without any +error, timeout, retry nor redispatch. In HTTP, the status code is checked too, +and a response with a status 5xx is not considered normal and will be logged +too. Of course, doing is is really discouraged as it will remove most of the +useful information from the logs. Do this only if you have no other +alternative. + + +8.4. Timing events +------------------ + +Timers provide a great help in troubleshooting network problems. All values are +reported in milliseconds (ms). These timers should be used in conjunction with +the session termination flags. In TCP mode with "option tcplog" set on the +frontend, 3 control points are reported under the form "Tw/Tc/Tt", and in HTTP +mode, 5 control points are reported under the form "TR/Tw/Tc/Tr/Ta". In +addition, three other measures are provided, "Th", "Ti", and "Tq". + +Timings events in HTTP mode: + + first request 2nd request + |<-------------------------------->|<-------------- ... + t tr t tr ... + ---|----|----|----|----|----|----|----|----|-- + : Th Ti TR Tw Tc Tr Td : Ti ... + :<---- Tq ---->: : + :<-------------- Tt -------------->: + :<-- -----Tu--------------->: + :<--------- Ta --------->: + +Timings events in TCP mode: + + TCP session + |<----------------->| + t t + ---|----|----|----|----|--- + | Th Tw Tc Td | + |<------ Tt ------->| + + - Th: total time to accept tcp connection and execute handshakes for low level + protocols. Currently, these protocols are proxy-protocol and SSL. This may + only happen once during the whole connection's lifetime. A large time here + may indicate that the client only pre-established the connection without + speaking, that it is experiencing network issues preventing it from + completing a handshake in a reasonable time (e.g. MTU issues), or that an + SSL handshake was very expensive to compute. Please note that this time is + reported only before the first request, so it is safe to average it over + all request to calculate the amortized value. The second and subsequent + request will always report zero here. + + - Ti: is the idle time before the HTTP request (HTTP mode only). This timer + counts between the end of the handshakes and the first byte of the HTTP + request. When dealing with a second request in keep-alive mode, it starts + to count after the end of the transmission the previous response. When a + multiplexed protocol such as HTTP/2 is used, it starts to count immediately + after the previous request. Some browsers pre-establish connections to a + server in order to reduce the latency of a future request, and keep them + pending until they need it. This delay will be reported as the idle time. A + value of -1 indicates that nothing was received on the connection. + + - TR: total time to get the client request (HTTP mode only). It's the time + elapsed between the first bytes received and the moment the proxy received + the empty line marking the end of the HTTP headers. The value "-1" + indicates that the end of headers has never been seen. This happens when + the client closes prematurely or times out. This time is usually very short + since most requests fit in a single packet. A large time may indicate a + request typed by hand during a test. + + - Tq: total time to get the client request from the accept date or since the + emission of the last byte of the previous response (HTTP mode only). It's + exactly equal to Th + Ti + TR unless any of them is -1, in which case it + returns -1 as well. This timer used to be very useful before the arrival of + HTTP keep-alive and browsers' pre-connect feature. It's recommended to drop + it in favor of TR nowadays, as the idle time adds a lot of noise to the + reports. + + - Tw: total time spent in the queues waiting for a connection slot. It + accounts for backend queue as well as the server queues, and depends on the + queue size, and the time needed for the server to complete previous + requests. The value "-1" means that the request was killed before reaching + the queue, which is generally what happens with invalid or denied requests. + + - Tc: total time to establish the TCP connection to the server. It's the time + elapsed between the moment the proxy sent the connection request, and the + moment it was acknowledged by the server, or between the TCP SYN packet and + the matching SYN/ACK packet in return. The value "-1" means that the + connection never established. + + - Tr: server response time (HTTP mode only). It's the time elapsed between + the moment the TCP connection was established to the server and the moment + the server sent its complete response headers. It purely shows its request + processing time, without the network overhead due to the data transmission. + It is worth noting that when the client has data to send to the server, for + instance during a POST request, the time already runs, and this can distort + apparent response time. For this reason, it's generally wise not to trust + too much this field for POST requests initiated from clients behind an + untrusted network. A value of "-1" here means that the last the response + header (empty line) was never seen, most likely because the server timeout + stroke before the server managed to process the request. + + - Ta: total active time for the HTTP request, between the moment the proxy + received the first byte of the request header and the emission of the last + byte of the response body. The exception is when the "logasap" option is + specified. In this case, it only equals (TR+Tw+Tc+Tr), and is prefixed with + a '+' sign. From this field, we can deduce "Td", the data transmission time, + by subtracting other timers when valid : + + Td = Ta - (TR + Tw + Tc + Tr) + + Timers with "-1" values have to be excluded from this equation. Note that + "Ta" can never be negative. + + - Tt: total session duration time, between the moment the proxy accepted it + and the moment both ends were closed. The exception is when the "logasap" + option is specified. In this case, it only equals (Th+Ti+TR+Tw+Tc+Tr), and + is prefixed with a '+' sign. From this field, we can deduce "Td", the data + transmission time, by subtracting other timers when valid : + + Td = Tt - (Th + Ti + TR + Tw + Tc + Tr) + + Timers with "-1" values have to be excluded from this equation. In TCP + mode, "Ti", "Tq" and "Tr" have to be excluded too. Note that "Tt" can never + be negative and that for HTTP, Tt is simply equal to (Th+Ti+Ta). + + - Tu: total estimated time as seen from client, between the moment the proxy + accepted it and the moment both ends were closed, without idle time. + This is useful to roughly measure end-to-end time as a user would see it, + without idle time pollution from keep-alive time between requests. This + timer in only an estimation of time seen by user as it assumes network + latency is the same in both directions. The exception is when the "logasap" + option is specified. In this case, it only equals (Th+TR+Tw+Tc+Tr), and is + prefixed with a '+' sign. + +These timers provide precious indications on trouble causes. Since the TCP +protocol defines retransmit delays of 3, 6, 12... seconds, we know for sure +that timers close to multiples of 3s are nearly always related to lost packets +due to network problems (wires, negotiation, congestion). Moreover, if "Ta" or +"Tt" is close to a timeout value specified in the configuration, it often means +that a session has been aborted on timeout. + +Most common cases : + + - If "Th" or "Ti" are close to 3000, a packet has probably been lost between + the client and the proxy. This is very rare on local networks but might + happen when clients are on far remote networks and send large requests. It + may happen that values larger than usual appear here without any network + cause. Sometimes, during an attack or just after a resource starvation has + ended, HAProxy may accept thousands of connections in a few milliseconds. + The time spent accepting these connections will inevitably slightly delay + processing of other connections, and it can happen that request times in the + order of a few tens of milliseconds are measured after a few thousands of + new connections have been accepted at once. Using one of the keep-alive + modes may display larger idle times since "Ti" measures the time spent + waiting for additional requests. + + - If "Tc" is close to 3000, a packet has probably been lost between the + server and the proxy during the server connection phase. This value should + always be very low, such as 1 ms on local networks and less than a few tens + of ms on remote networks. + + - If "Tr" is nearly always lower than 3000 except some rare values which seem + to be the average majored by 3000, there are probably some packets lost + between the proxy and the server. + + - If "Ta" is large even for small byte counts, it generally is because + neither the client nor the server decides to close the connection while + HAProxy is running in tunnel mode and both have agreed on a keep-alive + connection mode. In order to solve this issue, it will be needed to specify + one of the HTTP options to manipulate keep-alive or close options on either + the frontend or the backend. Having the smallest possible 'Ta' or 'Tt' is + important when connection regulation is used with the "maxconn" option on + the servers, since no new connection will be sent to the server until + another one is released. + +Other noticeable HTTP log cases ('xx' means any value to be ignored) : + + TR/Tw/Tc/Tr/+Ta The "option logasap" is present on the frontend and the log + was emitted before the data phase. All the timers are valid + except "Ta" which is shorter than reality. + + -1/xx/xx/xx/Ta The client was not able to send a complete request in time + or it aborted too early. Check the session termination flags + then "timeout http-request" and "timeout client" settings. + + TR/-1/xx/xx/Ta It was not possible to process the request, maybe because + servers were out of order, because the request was invalid + or forbidden by ACL rules. Check the session termination + flags. + + TR/Tw/-1/xx/Ta The connection could not establish on the server. Either it + actively refused it or it timed out after Ta-(TR+Tw) ms. + Check the session termination flags, then check the + "timeout connect" setting. Note that the tarpit action might + return similar-looking patterns, with "Tw" equal to the time + the client connection was maintained open. + + TR/Tw/Tc/-1/Ta The server has accepted the connection but did not return + a complete response in time, or it closed its connection + unexpectedly after Ta-(TR+Tw+Tc) ms. Check the session + termination flags, then check the "timeout server" setting. + + +8.5. Session state at disconnection +----------------------------------- + +TCP and HTTP logs provide a session termination indicator in the +"termination_state" field, just before the number of active connections. It is +2-characters long in TCP mode, and is extended to 4 characters in HTTP mode, +each of which has a special meaning : + + - On the first character, a code reporting the first event which caused the + session to terminate : + + C : the TCP session was unexpectedly aborted by the client. + + S : the TCP session was unexpectedly aborted by the server, or the + server explicitly refused it. + + P : the session was prematurely aborted by the proxy, because of a + connection limit enforcement, because a DENY filter was matched, + because of a security check which detected and blocked a dangerous + error in server response which might have caused information leak + (e.g. cacheable cookie). + + L : the session was locally processed by HAProxy and was not passed to + a server. This is what happens for stats and redirects. + + R : a resource on the proxy has been exhausted (memory, sockets, source + ports, ...). Usually, this appears during the connection phase, and + system logs should contain a copy of the precise error. If this + happens, it must be considered as a very serious anomaly which + should be fixed as soon as possible by any means. + + I : an internal error was identified by the proxy during a self-check. + This should NEVER happen, and you are encouraged to report any log + containing this, because this would almost certainly be a bug. It + would be wise to preventively restart the process after such an + event too, in case it would be caused by memory corruption. + + D : the session was killed by HAProxy because the server was detected + as down and was configured to kill all connections when going down. + + U : the session was killed by HAProxy on this backup server because an + active server was detected as up and was configured to kill all + backup connections when going up. + + K : the session was actively killed by an admin operating on HAProxy. + + c : the client-side timeout expired while waiting for the client to + send or receive data. + + s : the server-side timeout expired while waiting for the server to + send or receive data. + + - : normal session completion, both the client and the server closed + with nothing left in the buffers. + + - on the second character, the TCP or HTTP session state when it was closed : + + R : the proxy was waiting for a complete, valid REQUEST from the client + (HTTP mode only). Nothing was sent to any server. + + Q : the proxy was waiting in the QUEUE for a connection slot. This can + only happen when servers have a 'maxconn' parameter set. It can + also happen in the global queue after a redispatch consecutive to + a failed attempt to connect to a dying server. If no redispatch is + reported, then no connection attempt was made to any server. + + C : the proxy was waiting for the CONNECTION to establish on the + server. The server might at most have noticed a connection attempt. + + H : the proxy was waiting for complete, valid response HEADERS from the + server (HTTP only). + + D : the session was in the DATA phase. + + L : the proxy was still transmitting LAST data to the client while the + server had already finished. This one is very rare as it can only + happen when the client dies while receiving the last packets. + + T : the request was tarpitted. It has been held open with the client + during the whole "timeout tarpit" duration or until the client + closed, both of which will be reported in the "Tw" timer. + + - : normal session completion after end of data transfer. + + - the third character tells whether the persistence cookie was provided by + the client (only in HTTP mode) : + + N : the client provided NO cookie. This is usually the case for new + visitors, so counting the number of occurrences of this flag in the + logs generally indicate a valid trend for the site frequentation. + + I : the client provided an INVALID cookie matching no known server. + This might be caused by a recent configuration change, mixed + cookies between HTTP/HTTPS sites, persistence conditionally + ignored, or an attack. + + D : the client provided a cookie designating a server which was DOWN, + so either "option persist" was used and the client was sent to + this server, or it was not set and the client was redispatched to + another server. + + V : the client provided a VALID cookie, and was sent to the associated + server. + + E : the client provided a valid cookie, but with a last date which was + older than what is allowed by the "maxidle" cookie parameter, so + the cookie is consider EXPIRED and is ignored. The request will be + redispatched just as if there was no cookie. + + O : the client provided a valid cookie, but with a first date which was + older than what is allowed by the "maxlife" cookie parameter, so + the cookie is consider too OLD and is ignored. The request will be + redispatched just as if there was no cookie. + + U : a cookie was present but was not used to select the server because + some other server selection mechanism was used instead (typically a + "use-server" rule). + + - : does not apply (no cookie set in configuration). + + - the last character reports what operations were performed on the persistence + cookie returned by the server (only in HTTP mode) : + + N : NO cookie was provided by the server, and none was inserted either. + + I : no cookie was provided by the server, and the proxy INSERTED one. + Note that in "cookie insert" mode, if the server provides a cookie, + it will still be overwritten and reported as "I" here. + + U : the proxy UPDATED the last date in the cookie that was presented by + the client. This can only happen in insert mode with "maxidle". It + happens every time there is activity at a different date than the + date indicated in the cookie. If any other change happens, such as + a redispatch, then the cookie will be marked as inserted instead. + + P : a cookie was PROVIDED by the server and transmitted as-is. + + R : the cookie provided by the server was REWRITTEN by the proxy, which + happens in "cookie rewrite" or "cookie prefix" modes. + + D : the cookie provided by the server was DELETED by the proxy. + + - : does not apply (no cookie set in configuration). + +The combination of the two first flags gives a lot of information about what +was happening when the session terminated, and why it did terminate. It can be +helpful to detect server saturation, network troubles, local system resource +starvation, attacks, etc... + +The most common termination flags combinations are indicated below. They are +alphabetically sorted, with the lowercase set just after the upper case for +easier finding and understanding. + + Flags Reason + + -- Normal termination. + + CC The client aborted before the connection could be established to the + server. This can happen when HAProxy tries to connect to a recently + dead (or unchecked) server, and the client aborts while HAProxy is + waiting for the server to respond or for "timeout connect" to expire. + + CD The client unexpectedly aborted during data transfer. This can be + caused by a browser crash, by an intermediate equipment between the + client and HAProxy which decided to actively break the connection, + by network routing issues between the client and HAProxy, or by a + keep-alive session between the server and the client terminated first + by the client. + + cD The client did not send nor acknowledge any data for as long as the + "timeout client" delay. This is often caused by network failures on + the client side, or the client simply leaving the net uncleanly. + + CH The client aborted while waiting for the server to start responding. + It might be the server taking too long to respond or the client + clicking the 'Stop' button too fast. + + cH The "timeout client" stroke while waiting for client data during a + POST request. This is sometimes caused by too large TCP MSS values + for PPPoE networks which cannot transport full-sized packets. It can + also happen when client timeout is smaller than server timeout and + the server takes too long to respond. + + CQ The client aborted while its session was queued, waiting for a server + with enough empty slots to accept it. It might be that either all the + servers were saturated or that the assigned server was taking too + long a time to respond. + + CR The client aborted before sending a full HTTP request. Most likely + the request was typed by hand using a telnet client, and aborted + too early. The HTTP status code is likely a 400 here. Sometimes this + might also be caused by an IDS killing the connection between HAProxy + and the client. "option http-ignore-probes" can be used to ignore + connections without any data transfer. + + cR The "timeout http-request" stroke before the client sent a full HTTP + request. This is sometimes caused by too large TCP MSS values on the + client side for PPPoE networks which cannot transport full-sized + packets, or by clients sending requests by hand and not typing fast + enough, or forgetting to enter the empty line at the end of the + request. The HTTP status code is likely a 408 here. Note: recently, + some browsers started to implement a "pre-connect" feature consisting + in speculatively connecting to some recently visited web sites just + in case the user would like to visit them. This results in many + connections being established to web sites, which end up in 408 + Request Timeout if the timeout strikes first, or 400 Bad Request when + the browser decides to close them first. These ones pollute the log + and feed the error counters. Some versions of some browsers have even + been reported to display the error code. It is possible to work + around the undesirable effects of this behavior by adding "option + http-ignore-probes" in the frontend, resulting in connections with + zero data transfer to be totally ignored. This will definitely hide + the errors of people experiencing connectivity issues though. + + CT The client aborted while its session was tarpitted. It is important to + check if this happens on valid requests, in order to be sure that no + wrong tarpit rules have been written. If a lot of them happen, it + might make sense to lower the "timeout tarpit" value to something + closer to the average reported "Tw" timer, in order not to consume + resources for just a few attackers. + + LR The request was intercepted and locally handled by HAProxy. Generally + it means that this was a redirect or a stats request. + + SC The server or an equipment between it and HAProxy explicitly refused + the TCP connection (the proxy received a TCP RST or an ICMP message + in return). Under some circumstances, it can also be the network + stack telling the proxy that the server is unreachable (e.g. no route, + or no ARP response on local network). When this happens in HTTP mode, + the status code is likely a 502 or 503 here. + + sC The "timeout connect" stroke before a connection to the server could + complete. When this happens in HTTP mode, the status code is likely a + 503 or 504 here. + + SD The connection to the server died with an error during the data + transfer. This usually means that HAProxy has received an RST from + the server or an ICMP message from an intermediate equipment while + exchanging data with the server. This can be caused by a server crash + or by a network issue on an intermediate equipment. + + sD The server did not send nor acknowledge any data for as long as the + "timeout server" setting during the data phase. This is often caused + by too short timeouts on L4 equipment before the server (firewalls, + load-balancers, ...), as well as keep-alive sessions maintained + between the client and the server expiring first on HAProxy. + + SH The server aborted before sending its full HTTP response headers, or + it crashed while processing the request. Since a server aborting at + this moment is very rare, it would be wise to inspect its logs to + control whether it crashed and why. The logged request may indicate a + small set of faulty requests, demonstrating bugs in the application. + Sometimes this might also be caused by an IDS killing the connection + between HAProxy and the server. + + sH The "timeout server" stroke before the server could return its + response headers. This is the most common anomaly, indicating too + long transactions, probably caused by server or database saturation. + The immediate workaround consists in increasing the "timeout server" + setting, but it is important to keep in mind that the user experience + will suffer from these long response times. The only long term + solution is to fix the application. + + sQ The session spent too much time in queue and has been expired. See + the "timeout queue" and "timeout connect" settings to find out how to + fix this if it happens too often. If it often happens massively in + short periods, it may indicate general problems on the affected + servers due to I/O or database congestion, or saturation caused by + external attacks. + + PC The proxy refused to establish a connection to the server because the + process's socket limit has been reached while attempting to connect. + The global "maxconn" parameter may be increased in the configuration + so that it does not happen anymore. This status is very rare and + might happen when the global "ulimit-n" parameter is forced by hand. + + PD The proxy blocked an incorrectly formatted chunked encoded message in + a request or a response, after the server has emitted its headers. In + most cases, this will indicate an invalid message from the server to + the client. HAProxy supports chunk sizes of up to 2GB - 1 (2147483647 + bytes). Any larger size will be considered as an error. + + PH The proxy blocked the server's response, because it was invalid, + incomplete, dangerous (cache control), or matched a security filter. + In any case, an HTTP 502 error is sent to the client. One possible + cause for this error is an invalid syntax in an HTTP header name + containing unauthorized characters. It is also possible but quite + rare, that the proxy blocked a chunked-encoding request from the + client due to an invalid syntax, before the server responded. In this + case, an HTTP 400 error is sent to the client and reported in the + logs. Finally, it may be due to an HTTP header rewrite failure on the + response. In this case, an HTTP 500 error is sent (see + "tune.maxrewrite" and "http-response strict-mode" for more + inforomation). + + PR The proxy blocked the client's HTTP request, either because of an + invalid HTTP syntax, in which case it returned an HTTP 400 error to + the client, or because a deny filter matched, in which case it + returned an HTTP 403 error. It may also be due to an HTTP header + rewrite failure on the request. In this case, an HTTP 500 error is + sent (see "tune.maxrewrite" and "http-request strict-mode" for more + inforomation). + + PT The proxy blocked the client's request and has tarpitted its + connection before returning it a 500 server error. Nothing was sent + to the server. The connection was maintained open for as long as + reported by the "Tw" timer field. + + RC A local resource has been exhausted (memory, sockets, source ports) + preventing the connection to the server from establishing. The error + logs will tell precisely what was missing. This is very rare and can + only be solved by proper system tuning. + +The combination of the two last flags gives a lot of information about how +persistence was handled by the client, the server and by HAProxy. This is very +important to troubleshoot disconnections, when users complain they have to +re-authenticate. The commonly encountered flags are : + + -- Persistence cookie is not enabled. + + NN No cookie was provided by the client, none was inserted in the + response. For instance, this can be in insert mode with "postonly" + set on a GET request. + + II A cookie designating an invalid server was provided by the client, + a valid one was inserted in the response. This typically happens when + a "server" entry is removed from the configuration, since its cookie + value can be presented by a client when no other server knows it. + + NI No cookie was provided by the client, one was inserted in the + response. This typically happens for first requests from every user + in "insert" mode, which makes it an easy way to count real users. + + VN A cookie was provided by the client, none was inserted in the + response. This happens for most responses for which the client has + already got a cookie. + + VU A cookie was provided by the client, with a last visit date which is + not completely up-to-date, so an updated cookie was provided in + response. This can also happen if there was no date at all, or if + there was a date but the "maxidle" parameter was not set, so that the + cookie can be switched to unlimited time. + + EI A cookie was provided by the client, with a last visit date which is + too old for the "maxidle" parameter, so the cookie was ignored and a + new cookie was inserted in the response. + + OI A cookie was provided by the client, with a first visit date which is + too old for the "maxlife" parameter, so the cookie was ignored and a + new cookie was inserted in the response. + + DI The server designated by the cookie was down, a new server was + selected and a new cookie was emitted in the response. + + VI The server designated by the cookie was not marked dead but could not + be reached. A redispatch happened and selected another one, which was + then advertised in the response. + + +8.6. Non-printable characters +----------------------------- + +In order not to cause trouble to log analysis tools or terminals during log +consulting, non-printable characters are not sent as-is into log files, but are +converted to the two-digits hexadecimal representation of their ASCII code, +prefixed by the character '#'. The only characters that can be logged without +being escaped are comprised between 32 and 126 (inclusive). Obviously, the +escape character '#' itself is also encoded to avoid any ambiguity ("#23"). It +is the same for the character '"' which becomes "#22", as well as '{', '|' and +'}' when logging headers. + +Note that the space character (' ') is not encoded in headers, which can cause +issues for tools relying on space count to locate fields. A typical header +containing spaces is "User-Agent". + +Last, it has been observed that some syslog daemons such as syslog-ng escape +the quote ('"') with a backslash ('\'). The reverse operation can safely be +performed since no quote may appear anywhere else in the logs. + + +8.7. Capturing HTTP cookies +--------------------------- + +Cookie capture simplifies the tracking a complete user session. This can be +achieved using the "capture cookie" statement in the frontend. Please refer to +section 4.2 for more details. Only one cookie can be captured, and the same +cookie will simultaneously be checked in the request ("Cookie:" header) and in +the response ("Set-Cookie:" header). The respective values will be reported in +the HTTP logs at the "captured_request_cookie" and "captured_response_cookie" +locations (see section 8.2.3 about HTTP log format). When either cookie is +not seen, a dash ('-') replaces the value. This way, it's easy to detect when a +user switches to a new session for example, because the server will reassign it +a new cookie. It is also possible to detect if a server unexpectedly sets a +wrong cookie to a client, leading to session crossing. + + Examples : + # capture the first cookie whose name starts with "ASPSESSION" + capture cookie ASPSESSION len 32 + + # capture the first cookie whose name is exactly "vgnvisitor" + capture cookie vgnvisitor= len 32 + + +8.8. Capturing HTTP headers +--------------------------- + +Header captures are useful to track unique request identifiers set by an upper +proxy, virtual host names, user-agents, POST content-length, referrers, etc. In +the response, one can search for information about the response length, how the +server asked the cache to behave, or an object location during a redirection. + +Header captures are performed using the "capture request header" and "capture +response header" statements in the frontend. Please consult their definition in +section 4.2 for more details. + +It is possible to include both request headers and response headers at the same +time. Non-existent headers are logged as empty strings, and if one header +appears more than once, only its last occurrence will be logged. Request headers +are grouped within braces '{' and '}' in the same order as they were declared, +and delimited with a vertical bar '|' without any space. Response headers +follow the same representation, but are displayed after a space following the +request headers block. These blocks are displayed just before the HTTP request +in the logs. + +As a special case, it is possible to specify an HTTP header capture in a TCP +frontend. The purpose is to enable logging of headers which will be parsed in +an HTTP backend if the request is then switched to this HTTP backend. + + Example : + # This instance chains to the outgoing proxy + listen proxy-out + mode http + option httplog + option logasap + log global + server cache1 192.168.1.1:3128 + + # log the name of the virtual server + capture request header Host len 20 + + # log the amount of data uploaded during a POST + capture request header Content-Length len 10 + + # log the beginning of the referrer + capture request header Referer len 20 + + # server name (useful for outgoing proxies only) + capture response header Server len 20 + + # logging the content-length is useful with "option logasap" + capture response header Content-Length len 10 + + # log the expected cache behavior on the response + capture response header Cache-Control len 8 + + # the Via header will report the next proxy's name + capture response header Via len 20 + + # log the URL location during a redirection + capture response header Location len 20 + + >>> Aug 9 20:26:09 localhost \ + haproxy[2022]: 127.0.0.1:34014 [09/Aug/2004:20:26:09] proxy-out \ + proxy-out/cache1 0/0/0/162/+162 200 +350 - - ---- 0/0/0/0/0 0/0 \ + {fr.adserver.yahoo.co||http://fr.f416.mail.} {|864|private||} \ + "GET http://fr.adserver.yahoo.com/" + + >>> Aug 9 20:30:46 localhost \ + haproxy[2022]: 127.0.0.1:34020 [09/Aug/2004:20:30:46] proxy-out \ + proxy-out/cache1 0/0/0/182/+182 200 +279 - - ---- 0/0/0/0/0 0/0 \ + {w.ods.org||} {Formilux/0.1.8|3495|||} \ + "GET http://trafic.1wt.eu/ HTTP/1.1" + + >>> Aug 9 20:30:46 localhost \ + haproxy[2022]: 127.0.0.1:34028 [09/Aug/2004:20:30:46] proxy-out \ + proxy-out/cache1 0/0/2/126/+128 301 +223 - - ---- 0/0/0/0/0 0/0 \ + {www.sytadin.equipement.gouv.fr||http://trafic.1wt.eu/} \ + {Apache|230|||http://www.sytadin.} \ + "GET http://www.sytadin.equipement.gouv.fr/ HTTP/1.1" + + +8.9. Examples of logs +--------------------- + +These are real-world examples of logs accompanied with an explanation. Some of +them have been made up by hand. The syslog part has been removed for better +reading. Their sole purpose is to explain how to decipher them. + + >>> haproxy[674]: 127.0.0.1:33318 [15/Oct/2003:08:31:57.130] px-http \ + px-http/srv1 6559/0/7/147/6723 200 243 - - ---- 5/3/3/1/0 0/0 \ + "HEAD / HTTP/1.0" + + => long request (6.5s) entered by hand through 'telnet'. The server replied + in 147 ms, and the session ended normally ('----') + + >>> haproxy[674]: 127.0.0.1:33319 [15/Oct/2003:08:31:57.149] px-http \ + px-http/srv1 6559/1230/7/147/6870 200 243 - - ---- 324/239/239/99/0 \ + 0/9 "HEAD / HTTP/1.0" + + => Idem, but the request was queued in the global queue behind 9 other + requests, and waited there for 1230 ms. + + >>> haproxy[674]: 127.0.0.1:33320 [15/Oct/2003:08:32:17.654] px-http \ + px-http/srv1 9/0/7/14/+30 200 +243 - - ---- 3/3/3/1/0 0/0 \ + "GET /image.iso HTTP/1.0" + + => request for a long data transfer. The "logasap" option was specified, so + the log was produced just before transferring data. The server replied in + 14 ms, 243 bytes of headers were sent to the client, and total time from + accept to first data byte is 30 ms. + + >>> haproxy[674]: 127.0.0.1:33320 [15/Oct/2003:08:32:17.925] px-http \ + px-http/srv1 9/0/7/14/30 502 243 - - PH-- 3/2/2/0/0 0/0 \ + "GET /cgi-bin/bug.cgi? HTTP/1.0" + + => the proxy blocked a server response either because of an "http-response + deny" rule, or because the response was improperly formatted and not + HTTP-compliant, or because it blocked sensitive information which risked + being cached. In this case, the response is replaced with a "502 bad + gateway". The flags ("PH--") tell us that it was HAProxy who decided to + return the 502 and not the server. + + >>> haproxy[18113]: 127.0.0.1:34548 [15/Oct/2003:15:18:55.798] px-http \ + px-http/<NOSRV> -1/-1/-1/-1/8490 -1 0 - - CR-- 2/2/2/0/0 0/0 "" + + => the client never completed its request and aborted itself ("C---") after + 8.5s, while the proxy was waiting for the request headers ("-R--"). + Nothing was sent to any server. + + >>> haproxy[18113]: 127.0.0.1:34549 [15/Oct/2003:15:19:06.103] px-http \ + px-http/<NOSRV> -1/-1/-1/-1/50001 408 0 - - cR-- 2/2/2/0/0 0/0 "" + + => The client never completed its request, which was aborted by the + time-out ("c---") after 50s, while the proxy was waiting for the request + headers ("-R--"). Nothing was sent to any server, but the proxy could + send a 408 return code to the client. + + >>> haproxy[18989]: 127.0.0.1:34550 [15/Oct/2003:15:24:28.312] px-tcp \ + px-tcp/srv1 0/0/5007 0 cD 0/0/0/0/0 0/0 + + => This log was produced with "option tcplog". The client timed out after + 5 seconds ("c----"). + + >>> haproxy[18989]: 10.0.0.1:34552 [15/Oct/2003:15:26:31.462] px-http \ + px-http/srv1 3183/-1/-1/-1/11215 503 0 - - SC-- 205/202/202/115/3 \ + 0/0 "HEAD / HTTP/1.0" + + => The request took 3s to complete (probably a network problem), and the + connection to the server failed ('SC--') after 4 attempts of 2 seconds + (config says 'retries 3'), and no redispatch (otherwise we would have + seen "/+3"). Status code 503 was returned to the client. There were 115 + connections on this server, 202 connections on this proxy, and 205 on + the global process. It is possible that the server refused the + connection because of too many already established. + + +9. Supported filters +-------------------- + +Here are listed officially supported filters with the list of parameters they +accept. Depending on compile options, some of these filters might be +unavailable. The list of available filters is reported in haproxy -vv. + +See also : "filter" + +9.1. Trace +---------- + +filter trace [name <name>] [random-forwarding] [hexdump] + + Arguments: + <name> is an arbitrary name that will be reported in + messages. If no name is provided, "TRACE" is used. + + <quiet> inhibits trace messages. + + <random-forwarding> enables the random forwarding of parsed data. By + default, this filter forwards all previously parsed + data. With this parameter, it only forwards a random + amount of the parsed data. + + <hexdump> dumps all forwarded data to the server and the client. + +This filter can be used as a base to develop new filters. It defines all +callbacks and print a message on the standard error stream (stderr) with useful +information for all of them. It may be useful to debug the activity of other +filters or, quite simply, HAProxy's activity. + +Using <random-parsing> and/or <random-forwarding> parameters is a good way to +tests the behavior of a filter that parses data exchanged between a client and +a server by adding some latencies in the processing. + + +9.2. HTTP compression +--------------------- + +filter compression + +The HTTP compression has been moved in a filter in HAProxy 1.7. "compression" +keyword must still be used to enable and configure the HTTP compression. And +when no other filter is used, it is enough. When used with the cache or the +fcgi-app enabled, it is also enough. In this case, the compression is always +done after the response is stored in the cache. But it is mandatory to +explicitly use a filter line to enable the HTTP compression when at least one +filter other than the cache or the fcgi-app is used for the same +listener/frontend/backend. This is important to know the filters evaluation +order. + +See also : "compression", section 9.4 about the cache filter and section 9.5 + about the fcgi-app filter. + + +9.3. Stream Processing Offload Engine (SPOE) +-------------------------------------------- + +filter spoe [engine <name>] config <file> + + Arguments : + + <name> is the engine name that will be used to find the right scope in + the configuration file. If not provided, all the file will be + parsed. + + <file> is the path of the engine configuration file. This file can + contain configuration of several engines. In this case, each + part must be placed in its own scope. + +The Stream Processing Offload Engine (SPOE) is a filter communicating with +external components. It allows the offload of some specifics processing on the +streams in tiered applications. These external components and information +exchanged with them are configured in dedicated files, for the main part. It +also requires dedicated backends, defined in HAProxy configuration. + +SPOE communicates with external components using an in-house binary protocol, +the Stream Processing Offload Protocol (SPOP). + +For all information about the SPOE configuration and the SPOP specification, see +"doc/SPOE.txt". + +9.4. Cache +---------- + +filter cache <name> + + Arguments : + + <name> is name of the cache section this filter will use. + +The cache uses a filter to store cacheable responses. The HTTP rules +"cache-store" and "cache-use" must be used to define how and when to use a +cache. By default the corresponding filter is implicitly defined. And when no +other filters than fcgi-app or compression are used, it is enough. In such +case, the compression filter is always evaluated after the cache filter. But it +is mandatory to explicitly use a filter line to use a cache when at least one +filter other than the compression or the fcgi-app is used for the same +listener/frontend/backend. This is important to know the filters evaluation +order. + +See also : section 9.2 about the compression filter, section 9.5 about the + fcgi-app filter and section 6 about cache. + + +9.5. Fcgi-app +------------- + +filter fcgi-app <name> + + Arguments : + + <name> is name of the fcgi-app section this filter will use. + +The FastCGI application uses a filter to evaluate all custom parameters on the +request path, and to process the headers on the response path. the <name> must +reference an existing fcgi-app section. The directive "use-fcgi-app" should be +used to define the application to use. By default the corresponding filter is +implicitly defined. And when no other filters than cache or compression are +used, it is enough. But it is mandatory to explicitly use a filter line to a +fcgi-app when at least one filter other than the compression or the cache is +used for the same backend. This is important to know the filters evaluation +order. + +See also: "use-fcgi-app", section 9.2 about the compression filter, section 9.4 + about the cache filter and section 10 about FastCGI application. + + +9.6. OpenTracing +---------------- + +The OpenTracing filter adds native support for using distributed tracing in +HAProxy. This is enabled by sending an OpenTracing compliant request to one +of the supported tracers such as Datadog, Jaeger, Lightstep and Zipkin tracers. +Please note: tracers are not listed by any preference, but alphabetically. + +This feature is only enabled when HAProxy was built with USE_OT=1. + +The OpenTracing filter activation is done explicitly by specifying it in the +HAProxy configuration. If this is not done, the OpenTracing filter in no way +participates in the work of HAProxy. + +filter opentracing [id <id>] config <file> + + Arguments : + + <id> is the OpenTracing filter id that will be used to find the + right scope in the configuration file. If no filter id is + specified, 'ot-filter' is used as default. If scope is not + specified in the configuration file, it applies to all defined + OpenTracing filters. + + <file> is the path of the OpenTracing configuration file. The same + file can contain configurations for multiple OpenTracing + filters simultaneously. In that case we do not need to define + scope so the same configuration applies to all filters or each + filter must have its own scope defined. + +More detailed documentation related to the operation, configuration and use +of the filter can be found in the addons/ot directory. + + +10. FastCGI applications +------------------------- + +HAProxy is able to send HTTP requests to Responder FastCGI applications. This +feature was added in HAProxy 2.1. To do so, servers must be configured to use +the FastCGI protocol (using the keyword "proto fcgi" on the server line) and a +FastCGI application must be configured and used by the backend managing these +servers (using the keyword "use-fcgi-app" into the proxy section). Several +FastCGI applications may be defined, but only one can be used at a time by a +backend. + +HAProxy implements all features of the FastCGI specification for Responder +application. Especially it is able to multiplex several requests on a simple +connection. + +10.1. Setup +----------- + +10.1.1. Fcgi-app section +-------------------------- + +fcgi-app <name> + Declare a FastCGI application named <name>. To be valid, at least the + document root must be defined. + +acl <aclname> <criterion> [flags] [operator] <value> ... + Declare or complete an access list. + + See "acl" keyword in section 4.2 and section 7 about ACL usage for + details. ACLs defined for a FastCGI application are private. They cannot be + used by any other application or by any proxy. In the same way, ACLs defined + in any other section are not usable by a FastCGI application. However, + Pre-defined ACLs are available. + +docroot <path> + Define the document root on the remote host. <path> will be used to build + the default value of FastCGI parameters SCRIPT_FILENAME and + PATH_TRANSLATED. It is a mandatory setting. + +index <script-name> + Define the script name that will be appended after an URI that ends with a + slash ("/") to set the default value of the FastCGI parameter SCRIPT_NAME. It + is an optional setting. + + Example : + index index.php + +log-stderr global +log-stderr <address> [len <length>] [format <format>] + [sample <ranges>:<sample_size>] <facility> [<level> [<minlevel>]] + Enable logging of STDERR messages reported by the FastCGI application. + + See "log" keyword in section 4.2 for details. It is an optional setting. By + default STDERR messages are ignored. + +pass-header <name> [ { if | unless } <condition> ] + Specify the name of a request header which will be passed to the FastCGI + application. It may optionally be followed by an ACL-based condition, in + which case it will only be evaluated if the condition is true. + + Most request headers are already available to the FastCGI application, + prefixed with "HTTP_". Thus, this directive is only required to pass headers + that are purposefully omitted. Currently, the headers "Authorization", + "Proxy-Authorization" and hop-by-hop headers are omitted. + + Note that the headers "Content-type" and "Content-length" are never passed to + the FastCGI application because they are already converted into parameters. + +path-info <regex> + Define a regular expression to extract the script-name and the path-info from + the URL-decoded path. Thus, <regex> may have two captures: the first one to + capture the script name and the second one to capture the path-info. The + first one is mandatory, the second one is optional. This way, it is possible + to extract the script-name from the path ignoring the path-info. It is an + optional setting. If it is not defined, no matching is performed on the + path. and the FastCGI parameters PATH_INFO and PATH_TRANSLATED are not + filled. + + For security reason, when this regular expression is defined, the newline and + the null characters are forbidden from the path, once URL-decoded. The reason + to such limitation is because otherwise the matching always fails (due to a + limitation one the way regular expression are executed in HAProxy). So if one + of these two characters is found in the URL-decoded path, an error is + returned to the client. The principle of least astonishment is applied here. + + Example : + path-info ^(/.+\.php)(/.*)?$ # both script-name and path-info may be set + path-info ^(/.+\.php) # the path-info is ignored + +option get-values +no option get-values + Enable or disable the retrieve of variables about connection management. + + HAProxy is able to send the record FCGI_GET_VALUES on connection + establishment to retrieve the value for following variables: + + * FCGI_MAX_REQS The maximum number of concurrent requests this + application will accept. + + * FCGI_MPXS_CONNS "0" if this application does not multiplex connections, + "1" otherwise. + + Some FastCGI applications does not support this feature. Some others close + the connection immediately after sending their response. So, by default, this + option is disabled. + + Note that the maximum number of concurrent requests accepted by a FastCGI + application is a connection variable. It only limits the number of streams + per connection. If the global load must be limited on the application, the + server parameters "maxconn" and "pool-max-conn" must be set. In addition, if + an application does not support connection multiplexing, the maximum number + of concurrent requests is automatically set to 1. + +option keep-conn +no option keep-conn + Instruct the FastCGI application to keep the connection open or not after + sending a response. + + If disabled, the FastCGI application closes the connection after responding + to this request. By default, this option is enabled. + +option max-reqs <reqs> + Define the maximum number of concurrent requests this application will + accept. + + This option may be overwritten if the variable FCGI_MAX_REQS is retrieved + during connection establishment. Furthermore, if the application does not + support connection multiplexing, this option will be ignored. By default set + to 1. + +option mpxs-conns +no option mpxs-conns + Enable or disable the support of connection multiplexing. + + This option may be overwritten if the variable FCGI_MPXS_CONNS is retrieved + during connection establishment. It is disabled by default. + +set-param <name> <fmt> [ { if | unless } <condition> ] + Set a FastCGI parameter that should be passed to this application. Its + value, defined by <fmt> must follows the log-format rules (see section 8.2.4 + "Custom Log format"). It may optionally be followed by an ACL-based + condition, in which case it will only be evaluated if the condition is true. + + With this directive, it is possible to overwrite the value of default FastCGI + parameters. If the value is evaluated to an empty string, the rule is + ignored. These directives are evaluated in their declaration order. + + Example : + # PHP only, required if PHP was built with --enable-force-cgi-redirect + set-param REDIRECT_STATUS 200 + + set-param PHP_AUTH_DIGEST %[req.hdr(Authorization)] + + +10.1.2. Proxy section +--------------------- + +use-fcgi-app <name> + Define the FastCGI application to use for the backend. + + Arguments : + <name> is the name of the FastCGI application to use. + + This keyword is only available for HTTP proxies with the backend capability + and with at least one FastCGI server. However, FastCGI servers can be mixed + with HTTP servers. But except there is a good reason to do so, it is not + recommended (see section 10.3 about the limitations for details). Only one + application may be defined at a time per backend. + + Note that, once a FastCGI application is referenced for a backend, depending + on the configuration some processing may be done even if the request is not + sent to a FastCGI server. Rules to set parameters or pass headers to an + application are evaluated. + + +10.1.3. Example +--------------- + + frontend front-http + mode http + bind *:80 + bind *: + + use_backend back-dynamic if { path_reg ^/.+\.php(/.*)?$ } + default_backend back-static + + backend back-static + mode http + server www A.B.C.D:80 + + backend back-dynamic + mode http + use-fcgi-app php-fpm + server php-fpm A.B.C.D:9000 proto fcgi + + fcgi-app php-fpm + log-stderr global + option keep-conn + + docroot /var/www/my-app + index index.php + path-info ^(/.+\.php)(/.*)?$ + + +10.2. Default parameters +------------------------ + +A Responder FastCGI application has the same purpose as a CGI/1.1 program. In +the CGI/1.1 specification (RFC3875), several variables must be passed to the +script. So HAProxy set them and some others commonly used by FastCGI +applications. All these variables may be overwritten, with caution though. + + +-------------------+-----------------------------------------------------+ + | AUTH_TYPE | Identifies the mechanism, if any, used by HAProxy | + | | to authenticate the user. Concretely, only the | + | | BASIC authentication mechanism is supported. | + | | | + +-------------------+-----------------------------------------------------+ + | CONTENT_LENGTH | Contains the size of the message-body attached to | + | | the request. It means only requests with a known | + | | size are considered as valid and sent to the | + | | application. | + | | | + +-------------------+-----------------------------------------------------+ + | CONTENT_TYPE | Contains the type of the message-body attached to | + | | the request. It may not be set. | + | | | + +-------------------+-----------------------------------------------------+ + | DOCUMENT_ROOT | Contains the document root on the remote host under | + | | which the script should be executed, as defined in | + | | the application's configuration. | + | | | + +-------------------+-----------------------------------------------------+ + | GATEWAY_INTERFACE | Contains the dialect of CGI being used by HAProxy | + | | to communicate with the FastCGI application. | + | | Concretely, it is set to "CGI/1.1". | + | | | + +-------------------+-----------------------------------------------------+ + | PATH_INFO | Contains the portion of the URI path hierarchy | + | | following the part that identifies the script | + | | itself. To be set, the directive "path-info" must | + | | be defined. | + | | | + +-------------------+-----------------------------------------------------+ + | PATH_TRANSLATED | If PATH_INFO is set, it is its translated version. | + | | It is the concatenation of DOCUMENT_ROOT and | + | | PATH_INFO. If PATH_INFO is not set, this parameters | + | | is not set too. | + | | | + +-------------------+-----------------------------------------------------+ + | QUERY_STRING | Contains the request's query string. It may not be | + | | set. | + | | | + +-------------------+-----------------------------------------------------+ + | REMOTE_ADDR | Contains the network address of the client sending | + | | the request. | + | | | + +-------------------+-----------------------------------------------------+ + | REMOTE_USER | Contains the user identification string supplied by | + | | client as part of user authentication. | + | | | + +-------------------+-----------------------------------------------------+ + | REQUEST_METHOD | Contains the method which should be used by the | + | | script to process the request. | + | | | + +-------------------+-----------------------------------------------------+ + | REQUEST_URI | Contains the request's URI. | + | | | + +-------------------+-----------------------------------------------------+ + | SCRIPT_FILENAME | Contains the absolute pathname of the script. it is | + | | the concatenation of DOCUMENT_ROOT and SCRIPT_NAME. | + | | | + +-------------------+-----------------------------------------------------+ + | SCRIPT_NAME | Contains the name of the script. If the directive | + | | "path-info" is defined, it is the first part of the | + | | URI path hierarchy, ending with the script name. | + | | Otherwise, it is the entire URI path. | + | | | + +-------------------+-----------------------------------------------------+ + | SERVER_NAME | Contains the name of the server host to which the | + | | client request is directed. It is the value of the | + | | header "Host", if defined. Otherwise, the | + | | destination address of the connection on the client | + | | side. | + | | | + +-------------------+-----------------------------------------------------+ + | SERVER_PORT | Contains the destination TCP port of the connection | + | | on the client side, which is the port the client | + | | connected to. | + | | | + +-------------------+-----------------------------------------------------+ + | SERVER_PROTOCOL | Contains the request's protocol. | + | | | + +-------------------+-----------------------------------------------------+ + | SERVER_SOFTWARE | Contains the string "HAProxy" followed by the | + | | current HAProxy version. | + | | | + +-------------------+-----------------------------------------------------+ + | HTTPS | Set to a non-empty value ("on") if the script was | + | | queried through the HTTPS protocol. | + | | | + +-------------------+-----------------------------------------------------+ + + +10.3. Limitations +------------------ + +The current implementation have some limitations. The first one is about the +way some request headers are hidden to the FastCGI applications. This happens +during the headers analysis, on the backend side, before the connection +establishment. At this stage, HAProxy know the backend is using a FastCGI +application but it don't know if the request will be routed to a FastCGI server +or not. But to hide request headers, it simply removes them from the HTX +message. So, if the request is finally routed to an HTTP server, it never see +these headers. For this reason, it is not recommended to mix FastCGI servers +and HTTP servers under the same backend. + +Similarly, the rules "set-param" and "pass-header" are evaluated during the +request headers analysis. So the evaluation is always performed, even if the +requests is finally forwarded to an HTTP server. + +About the rules "set-param", when a rule is applied, a pseudo header is added +into the HTX message. So, the same way than for HTTP header rewrites, it may +fail if the buffer is full. The rules "set-param" will compete with +"http-request" ones. + +Finally, all FastCGI params and HTTP headers are sent into a unique record +FCGI_PARAM. Encoding of this record must be done in one pass, otherwise a +processing error is returned. It means the record FCGI_PARAM, once encoded, +must not exceeds the size of a buffer. However, there is no reserve to respect +here. + + +11. Address formats +------------------- + +Several statements as "bind, "server", "nameserver" and "log" requires an +address. + +This address can be a host name, an IPv4 address, an IPv6 address, or '*'. +The '*' is equal to the special address "0.0.0.0" and can be used, in the case +of "bind" or "dgram-bind" to listen on all IPv4 of the system.The IPv6 +equivalent is '::'. + +Depending of the statement, a port or port range follows the IP address. This +is mandatory on 'bind' statement, optional on 'server'. + +This address can also begin with a slash '/'. It is considered as the "unix" +family, and '/' and following characters must be present the path. + +Default socket type or transport method "datagram" or "stream" depends on the +configuration statement showing the address. Indeed, 'bind' and 'server' will +use a "stream" socket type by default whereas 'log', 'nameserver' or +'dgram-bind' will use a "datagram". + +Optionally, a prefix could be used to force the address family and/or the +socket type and the transport method. + + +11.1. Address family prefixes +----------------------------- + +'abns@<name>' following <name> is an abstract namespace (Linux only). + +'fd@<n>' following address is a file descriptor <n> inherited from the + parent. The fd must be bound and may or may not already be + listening. + +'ip@<address>[:port1[-port2]]' following <address> is considered as an IPv4 or + IPv6 address depending on the syntax. Depending + on the statement using this address, a port or + a port range may or must be specified. + +'ipv4@<address>[:port1[-port2]]' following <address> is always considered as + an IPv4 address. Depending on the statement + using this address, a port or a port range + may or must be specified. + +'ipv6@<address>[:port1[-port2]]' following <address> is always considered as + an IPv6 address. Depending on the statement + using this address, a port or a port range + may or must be specified. + +'sockpair@<n>' following address is the file descriptor of a connected unix + socket or of a socketpair. During a connection, the initiator + creates a pair of connected sockets, and passes one of them + over the FD to the other end. The listener waits to receive + the FD from the unix socket and uses it as if it were the FD + of an accept(). Should be used carefully. + +'unix@<path>' following string is considered as a UNIX socket <path>. this + prefix is useful to declare an UNIX socket path which don't + start by slash '/'. + + +11.2. Socket type prefixes +-------------------------- + +Previous "Address family prefixes" can also be prefixed to force the socket +type and the transport method. The default depends of the statement using +this address but in some cases the user may force it to a different one. +This is the case for "log" statement where the default is syslog over UDP +but we could force to use syslog over TCP. + +Those prefixes were designed for internal purpose and users should +instead use aliases of the next section "11.3 Protocol prefixes". + +If users need one those prefixes to perform what they expect because +they can not configure the same using the protocol prefixes, they should +report this to the maintainers. + +'stream+<family>@<address>' forces socket type and transport method + to "stream" + +'dgram+<family>@<address>' forces socket type and transport method + to "datagram". + + +11.3. Protocol prefixes +----------------------- + +'quic4@<address>[:port1[-port2]]' following <address> is always considered as + an IPv4 address but socket type is forced to + "datagram" and the transport method is forced + to "stream". Depending on the statement using + this address, a UDP port or port range can or + must be specified. + +'quic6@<address>[:port1[-port2]]' following <address> is always considered as + an IPv6 address but socket type is forced to + "datagram" and the transport method is forced + to "stream". Depending on the statement using + this address, a UDP port or port range can or + must be specified. + +'tcp@<address>[:port1[-port2]]' following <address> is considered as an IPv4 + or IPv6 address depending of the syntax but + socket type and transport method is forced to + "stream". Depending on the statement using + this address, a port or a port range can or + must be specified. It is considered as an alias + of 'stream+ip@'. + +'tcp4@<address>[:port1[-port2]]' following <address> is always considered as + an IPv4 address but socket type and transport + method is forced to "stream". Depending on the + statement using this address, a port or port + range can or must be specified. + It is considered as an alias of 'stream+ipv4@'. + +'tcp6@<address>[:port1[-port2]]' following <address> is always considered as + an IPv6 address but socket type and transport + method is forced to "stream". Depending on the + statement using this address, a port or port + range can or must be specified. + It is considered as an alias of 'stream+ipv4@'. + +'udp@<address>[:port1[-port2]]' following <address> is considered as an IPv4 + or IPv6 address depending of the syntax but + socket type and transport method is forced to + "datagram". Depending on the statement using + this address, a port or a port range can or + must be specified. It is considered as an alias + of 'dgram+ip@'. + +'udp4@<address>[:port1[-port2]]' following <address> is always considered as + an IPv4 address but socket type and transport + method is forced to "datagram". Depending on + the statement using this address, a port or + port range can or must be specified. + It is considered as an alias of 'dgram+ipv4@'. + +'udp6@<address>[:port1[-port2]]' following <address> is always considered as + an IPv6 address but socket type and transport + method is forced to "datagram". Depending on + the statement using this address, a port or + port range can or must be specified. + It is considered as an alias of 'dgram+ipv4@'. + +'uxdg@<path>' following string is considered as a unix socket <path> but + transport method is forced to "datagram". It is considered as + an alias of 'dgram+unix@'. + +'uxst@<path>' following string is considered as a unix socket <path> but + transport method is forced to "stream". It is considered as + an alias of 'stream+unix@'. + +In future versions, other prefixes could be used to specify protocols like +QUIC which proposes stream transport based on socket of type "datagram". + +/* + * Local variables: + * fill-column: 79 + * End: + */ |