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+ ----------------------
+ 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:
+ */