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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:01:30 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:01:30 +0000 |
| commit | 6beeb1b708550be0d4a53b272283e17e5e35fe17 (patch) | |
| tree | 1ce8673d4aaa948e5554000101f46536a1e4cc29 /docs/manual/sections.html.en | |
| parent | Initial commit. (diff) | |
| download | apache2-upstream/2.4.57.tar.xz apache2-upstream/2.4.57.zip | |
Adding upstream version 2.4.57.upstream/2.4.57
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'docs/manual/sections.html.en')
| -rw-r--r-- | docs/manual/sections.html.en | 607 |
1 files changed, 607 insertions, 0 deletions
diff --git a/docs/manual/sections.html.en b/docs/manual/sections.html.en new file mode 100644 index 0000000..71885e9 --- /dev/null +++ b/docs/manual/sections.html.en @@ -0,0 +1,607 @@ +<?xml version="1.0" encoding="UTF-8"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head> +<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" /> +<!-- + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + This file is generated from xml source: DO NOT EDIT + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + --> +<title>Configuration Sections - Apache HTTP Server Version 2.4</title> +<link href="./style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> +<link href="./style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> +<link href="./style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="./style/css/prettify.css" /> +<script src="./style/scripts/prettify.min.js" type="text/javascript"> +</script> + +<link href="./images/favicon.ico" rel="shortcut icon" /></head> +<body id="manual-page"><div id="page-header"> +<p class="menu"><a href="./mod/">Modules</a> | <a href="./mod/directives.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="./glossary.html">Glossary</a> | <a href="./sitemap.html">Sitemap</a></p> +<p class="apache">Apache HTTP Server Version 2.4</p> +<img alt="" src="./images/feather.png" /></div> +<div class="up"><a href="./"><img title="<-" alt="<-" src="./images/left.gif" /></a></div> +<div id="path"> +<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="./">Version 2.4</a></div><div id="page-content"><div id="preamble"><h1>Configuration Sections</h1> +<div class="toplang"> +<p><span>Available Languages: </span><a href="./en/sections.html" title="English"> en </a> | +<a href="./fr/sections.html" hreflang="fr" rel="alternate" title="Français"> fr </a> | +<a href="./ja/sections.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | +<a href="./ko/sections.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> | +<a href="./tr/sections.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p> +</div> + <p>Directives in the <a href="configuring.html">configuration files</a> may apply to the +entire server, or they may be restricted to apply only to particular +directories, files, hosts, or URLs. This document describes how to +use configuration section containers or <code>.htaccess</code> files +to change the scope of other configuration directives.</p> +</div> +<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><ul id="toc"><li><img alt="" src="./images/down.gif" /> <a href="#types">Types of Configuration Section Containers</a></li> +<li><img alt="" src="./images/down.gif" /> <a href="#file-and-web">Filesystem, Webspace, and Boolean Expressions</a></li> +<li><img alt="" src="./images/down.gif" /> <a href="#virtualhost">Virtual Hosts</a></li> +<li><img alt="" src="./images/down.gif" /> <a href="#proxy">Proxy</a></li> +<li><img alt="" src="./images/down.gif" /> <a href="#whatwhere">What Directives are Allowed?</a></li> +<li><img alt="" src="./images/down.gif" /> <a href="#merging">How the sections are merged</a></li> +</ul><h3>See also</h3><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div> +<div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div> +<div class="section"> +<h2><a name="types" id="types">Types of Configuration Section Containers</a></h2> + +<table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td><ul><li><code class="module"><a href="./mod/core.html">core</a></code></li><li><code class="module"><a href="./mod/mod_version.html">mod_version</a></code></li><li><code class="module"><a href="./mod/mod_proxy.html">mod_proxy</a></code></li></ul></td><td><ul><li><code class="directive"><a href="./mod/core.html#directory"><Directory></a></code></li><li><code class="directive"><a href="./mod/core.html#directorymatch"><DirectoryMatch></a></code></li><li><code class="directive"><a href="./mod/core.html#files"><Files></a></code></li><li><code class="directive"><a href="./mod/core.html#filesmatch"><FilesMatch></a></code></li><li><code class="directive"><a href="./mod/core.html#if"><If></a></code></li><li><code class="directive"><a href="./mod/core.html#ifdefine"><IfDefine></a></code></li><li><code class="directive"><a href="./mod/core.html#ifmodule"><IfModule></a></code></li><li><code class="directive"><a href="./mod/mod_version.html#ifversion"><IfVersion></a></code></li><li><code class="directive"><a href="./mod/core.html#location"><Location></a></code></li><li><code class="directive"><a href="./mod/core.html#locationmatch"><LocationMatch></a></code></li><li><code class="directive"><a href="./mod/mod_md.html#mdomainsetsection"><MDomainSet></a></code></li><li><code class="directive"><a href="./mod/mod_proxy.html#proxy"><Proxy></a></code></li><li><code class="directive"><a href="./mod/mod_proxy.html#proxymatch"><ProxyMatch></a></code></li><li><code class="directive"><a href="./mod/core.html#virtualhost"><VirtualHost></a></code></li></ul></td></tr></table> + +<p>There are two basic types of containers. Most containers are +evaluated for each request. The enclosed directives are applied only +for those requests that match the containers. The <code class="directive"><a href="./mod/core.html#ifdefine"><IfDefine></a></code>, <code class="directive"><a href="./mod/core.html#ifmodule"><IfModule></a></code>, and +<code class="directive"><a href="./mod/mod_version.html#ifversion"><IfVersion></a></code> +containers, on the other hand, are evaluated only at server startup +and restart. If their conditions are true at startup, then the +enclosed directives will apply to all requests. If the conditions are +not true, the enclosed directives will be ignored.</p> + +<p>The <code class="directive"><a href="./mod/core.html#ifdefine"><IfDefine></a></code> directive +encloses directives that will only be applied if an appropriate +parameter is defined on the <code class="program"><a href="./programs/httpd.html">httpd</a></code> command line. For example, +with the following configuration, all requests will be redirected +to another site only if the server is started using +<code>httpd -DClosedForNow</code>:</p> + +<pre class="prettyprint lang-config"><IfDefine ClosedForNow> + Redirect "/" "http://otherserver.example.com/" +</IfDefine></pre> + + +<p>The <code class="directive"><a href="./mod/core.html#ifmodule"><IfModule></a></code> +directive is very similar, except it encloses directives that will +only be applied if a particular module is available in the server. +The module must either be statically compiled in the server, or it +must be dynamically compiled and its <code class="directive"><a href="./mod/mod_so.html#loadmodule">LoadModule</a></code> line must be earlier in the +configuration file. This directive should only be used if you need +your configuration file to work whether or not certain modules are +installed. It should not be used to enclose directives that you want +to work all the time, because it can suppress useful error messages +about missing modules.</p> + +<p>In the following example, the <code class="directive"><a href="./mod/mod_mime_magic.html#mimemagicfile">MimeMagicFile</a></code> directive will be +applied only if <code class="module"><a href="./mod/mod_mime_magic.html">mod_mime_magic</a></code> is available.</p> + +<pre class="prettyprint lang-config"><IfModule mod_mime_magic.c> + MimeMagicFile "conf/magic" +</IfModule></pre> + + +<p>The <code class="directive"><a href="./mod/mod_version.html#ifversion"><IfVersion></a></code> +directive is very similar to <code class="directive"><a href="./mod/core.html#ifdefine"><IfDefine></a></code> and <code class="directive"><a href="./mod/core.html#ifmodule"><IfModule></a></code>, except it encloses directives that will +only be applied if a particular version of the server is executing. This +module is designed for the use in test suites and large networks which have to +deal with different httpd versions and different configurations.</p> + +<pre class="prettyprint lang-config"><IfVersion >= 2.4> + # this happens only in versions greater or + # equal 2.4.0. +</IfVersion></pre> + + +<p><code class="directive"><a href="./mod/core.html#ifdefine"><IfDefine></a></code>, +<code class="directive"><a href="./mod/core.html#ifmodule"><IfModule></a></code>, and the +<code class="directive"><a href="./mod/mod_version.html#ifversion"><IfVersion></a></code> +can apply negative conditions by preceding their test with "!". +Also, these sections can be nested to achieve more complex +restrictions.</p> +</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div> +<div class="section"> +<h2><a name="file-and-web" id="file-and-web">Filesystem, Webspace, and Boolean Expressions</a></h2> + +<p>The most commonly used configuration section containers are the +ones that change the configuration of particular places in the +filesystem or webspace. First, it is important to understand the +difference between the two. The filesystem is the view of your disks +as seen by your operating system. For example, in a default install, +Apache httpd resides at <code>/usr/local/apache2</code> in the Unix +filesystem or <code>"c:/Program Files/Apache Group/Apache2"</code> in +the Windows filesystem. (Note that forward slashes should always be +used as the path separator in Apache httpd configuration files, even for Windows.) In contrast, +the webspace is the view of your site as delivered by the web server +and seen by the client. So the path <code>/dir/</code> in the +webspace corresponds to the path +<code>/usr/local/apache2/htdocs/dir/</code> in the filesystem of a +default Apache httpd install on Unix. The webspace need not map directly to +the filesystem, since webpages may be generated dynamically +from databases or other locations.</p> + +<h3><a name="filesystem" id="filesystem">Filesystem Containers</a></h3> + +<p>The <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> +and <code class="directive"><a href="./mod/core.html#files"><Files></a></code> +directives, along with their <a class="glossarylink" href="./glossary.html#regex" title="see glossary">regex</a> +counterparts, apply directives to +parts of the filesystem. Directives enclosed in a <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> section apply to +the named filesystem directory and all subdirectories of that +directory (as well as the files in those directories). +The same effect can be obtained using <a href="howto/htaccess.html">.htaccess files</a>. For example, in the +following configuration, directory indexes will be enabled for the +<code>/var/web/dir1</code> directory and all subdirectories.</p> + +<pre class="prettyprint lang-config"><Directory "/var/web/dir1"> + Options +Indexes +</Directory></pre> + + +<p>Directives enclosed in a <code class="directive"><a href="./mod/core.html#files"><Files></a></code> section apply to any file with +the specified name, regardless of what directory it lies in. +So for example, the following configuration directives will, +when placed in the main section of the configuration file, +deny access to any file named <code>private.html</code> regardless +of where it is found.</p> + +<pre class="prettyprint lang-config"><Files "private.html"> + Require all denied +</Files></pre> + + +<p>To address files found in a particular part of the filesystem, the +<code class="directive"><a href="./mod/core.html#files"><Files></a></code> and +<code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> sections +can be combined. For example, the following configuration will deny +access to <code>/var/web/dir1/private.html</code>, +<code>/var/web/dir1/subdir2/private.html</code>, +<code>/var/web/dir1/subdir3/private.html</code>, and any other instance +of <code>private.html</code> found under the <code>/var/web/dir1/</code> +directory.</p> + +<pre class="prettyprint lang-config"><Directory "/var/web/dir1"> + <Files "private.html"> + Require all denied + </Files> +</Directory></pre> + + + +<h3><a name="webspace" id="webspace">Webspace Containers</a></h3> + +<p>The <code class="directive"><a href="./mod/core.html#location"><Location></a></code> +directive and its <a class="glossarylink" href="./glossary.html#regex" title="see glossary">regex</a> counterpart, on +the other hand, change the +configuration for content in the webspace. For example, the following +configuration prevents access to any URL-path that begins in /private. +In particular, it will apply to requests for +<code>http://yoursite.example.com/private</code>, +<code>http://yoursite.example.com/private123</code>, and +<code>http://yoursite.example.com/private/dir/file.html</code> as well +as any other requests starting with the <code>/private</code> string.</p> + +<pre class="prettyprint lang-config"><LocationMatch "^/private"> + Require all denied +</LocationMatch></pre> + + +<p>The <code class="directive"><a href="./mod/core.html#location"><Location></a></code> +directive need not have anything to do with the filesystem. +For example, the following example shows how to map a particular +URL to an internal Apache HTTP Server handler provided by <code class="module"><a href="./mod/mod_status.html">mod_status</a></code>. +No file called <code>server-status</code> needs to exist in the +filesystem.</p> + +<pre class="prettyprint lang-config"><Location "/server-status"> + SetHandler server-status +</Location></pre> + + + +<h3><a name="overlapping-webspace" id="overlapping-webspace">Overlapping Webspace</a></h3> +<p>In order to have two overlapping URLs one has to consider the order in which +certain sections or directives are evaluated. For +<code class="directive"><a href="./mod/core.html#location"><Location></a></code> this would be:</p> +<pre class="prettyprint lang-config"><Location "/foo"> +</Location> +<Location "/foo/bar"> +</Location></pre> + +<p><code class="directive"><a href="./mod/mod_alias.html#alias"><Alias></a></code>es on the other hand, +are mapped vice-versa:</p> +<pre class="prettyprint lang-config">Alias "/foo/bar" "/srv/www/uncommon/bar" +Alias "/foo" "/srv/www/common/foo"</pre> + +<p>The same is true for the <code class="directive"><a href="./mod/mod_proxy.html#proxypass">ProxyPass</a></code> +directives:</p> +<pre class="prettyprint lang-config">ProxyPass "/special-area" "http://special.example.com" smax=5 max=10 +ProxyPass "/" "balancer://mycluster/" stickysession=JSESSIONID|jsessionid nofailover=On</pre> + + + +<h3><a name="wildcards" id="wildcards">Wildcards and Regular Expressions</a></h3> + +<p>The <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code>, +<code class="directive"><a href="./mod/core.html#files"><Files></a></code>, and +<code class="directive"><a href="./mod/core.html#location"><Location></a></code> +directives can each use shell-style wildcard characters as in +<code>fnmatch</code> from the C standard library. The character "*" +matches any sequence of characters, "?" matches any single character, +and "[<em>seq</em>]" matches any character in <em>seq</em>. The "/" +character will not be matched by any wildcard; it must be specified +explicitly.</p> + +<p>If even more flexible matching is required, each +container has a regular expression (regex) counterpart <code class="directive"><a href="./mod/core.html#directorymatch"><DirectoryMatch></a></code>, <code class="directive"><a href="./mod/core.html#filesmatch"><FilesMatch></a></code>, and <code class="directive"><a href="./mod/core.html#locationmatch"><LocationMatch></a></code> that allow +perl-compatible +<a class="glossarylink" href="./glossary.html#regex" title="see glossary">regular expressions</a> +to be used in choosing the matches. But see the section below on +configuration merging to find out how using regex sections will change +how directives are applied.</p> + +<p>A non-regex wildcard section that changes the configuration of +all user directories could look as follows:</p> + +<pre class="prettyprint lang-config"><Directory "/home/*/public_html"> + Options Indexes +</Directory></pre> + + +<p>Using regex sections, we can deny access to many types of image files +at once:</p> +<pre class="prettyprint lang-config"><FilesMatch "\.(?i:gif|jpe?g|png)$"> + Require all denied +</FilesMatch></pre> + + +<p>Regular expressions containing <strong>named groups and +backreferences</strong> are added to the environment with the +corresponding name in uppercase. This allows elements of filename paths +and URLs to be referenced from within <a href="expr.html">expressions</a> +and modules like <code class="module"><a href="./mod/mod_rewrite.html">mod_rewrite</a></code>.</p> + +<pre class="prettyprint lang-config"><DirectoryMatch "^/var/www/combined/(?<SITENAME>[^/]+)"> + Require ldap-group "cn=%{env:MATCH_SITENAME},ou=combined,o=Example" +</DirectoryMatch></pre> + + + + +<h3><a name="expressions" id="expressions">Boolean expressions</a></h3> +<p>The <code class="directive"><a href="./mod/core.html#if"><If></a></code> +directive change the configuration depending on a condition which can be +expressed by a boolean expression. For example, the following configuration +denies access if the HTTP Referer header does not start with +"http://www.example.com/".</p> +<pre class="prettyprint lang-config"><If "!(%{HTTP_REFERER} -strmatch 'http://www.example.com/*')"> + Require all denied +</If></pre> + + + + +<h3><a name="whichwhen" id="whichwhen">What to use When</a></h3> + +<p>Choosing between filesystem containers and webspace containers is +actually quite easy. When applying directives to objects that reside +in the filesystem always use <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> or <code class="directive"><a href="./mod/core.html#files"><Files></a></code>. When applying directives to objects +that do not reside in the filesystem (such as a webpage generated from +a database), use <code class="directive"><a href="./mod/core.html#location"><Location></a></code>.</p> + +<p>It is important to never use <code class="directive"><a href="./mod/core.html#location"><Location></a></code> when trying to restrict +access to objects in the filesystem. This is because many +different webspace locations (URLs) could map to the same filesystem +location, allowing your restrictions to be circumvented. +For example, consider the following configuration:</p> + +<pre class="prettyprint lang-config"><Location "/dir/"> + Require all denied +</Location></pre> + + +<p>This works fine if the request is for +<code>http://yoursite.example.com/dir/</code>. But what if you are on +a case-insensitive filesystem? Then your restriction could be easily +circumvented by requesting +<code>http://yoursite.example.com/DIR/</code>. The <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> directive, in +contrast, will apply to any content served from that location, +regardless of how it is called. (An exception is filesystem links. +The same directory can be placed in more than one part of the +filesystem using symbolic links. The <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> directive will follow the symbolic +link without resetting the pathname. Therefore, for the highest level +of security, symbolic links should be disabled with the appropriate +<code class="directive"><a href="./mod/core.html#options">Options</a></code> directive.)</p> + +<p>If you are, perhaps, thinking that none of this applies to you +because you use a case-sensitive filesystem, remember that there are +many other ways to map multiple webspace locations to the same +filesystem location. Therefore you should always use the filesystem +containers when you can. There is, however, one exception to this +rule. Putting configuration restrictions in a <code><Location +"/"></code> section is perfectly safe because this section will apply +to all requests regardless of the specific URL.</p> + + +<h3><a name="nesting" id="nesting">Nesting of sections</a></h3> + +<p>Some section types can be nested inside other section types. On the one +hand, <code class="directive"><a href="./mod/core.html#files"><Files></a></code> can be used +inside <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code>. On +the other hand, <code class="directive"><a href="./mod/core.html#if"><If></a></code> can +be used inside <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code>, +<code class="directive"><a href="./mod/core.html#location"><Location></a></code>, and <code class="directive"><a href="./mod/core.html#files"><Files></a></code> sections (but not inside another +<code class="directive"><a href="./mod/core.html#if"><If></a></code>). The regex +counterparts of the named section behave identically.</p> + +<p>Nested sections are merged after non-nested sections of the same type.</p> + + + +</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div> +<div class="section"> +<h2><a name="virtualhost" id="virtualhost">Virtual Hosts</a></h2> + +<p>The <code class="directive"><a href="./mod/core.html#virtualhost"><VirtualHost></a></code> +container encloses directives that apply to specific hosts. +This is useful when serving multiple hosts from the same machine +with a different configuration for each. For more information, +see the <a href="vhosts/">Virtual Host Documentation</a>.</p> +</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div> +<div class="section"> +<h2><a name="proxy" id="proxy">Proxy</a></h2> + +<p>The <code class="directive"><a href="./mod/mod_proxy.html#proxy"><Proxy></a></code> +and <code class="directive"><a href="./mod/mod_proxy.html#proxymatch"><ProxyMatch></a></code> +containers apply enclosed configuration directives only +to sites accessed through <code class="module"><a href="./mod/mod_proxy.html">mod_proxy</a></code>'s proxy server +that match the specified URL. For example, the following configuration +will allow only a subset of clients to access the +<code>www.example.com</code> website using the proxy server:</p> + +<pre class="prettyprint lang-config"><Proxy "http://www.example.com/*"> + Require host yournetwork.example.com +</Proxy></pre> + +</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div> +<div class="section"> +<h2><a name="whatwhere" id="whatwhere">What Directives are Allowed?</a></h2> + +<p>To find out what directives are allowed in what types of +configuration sections, check the <a href="mod/directive-dict.html#Context">Context</a> of the directive. +Everything that is allowed in +<code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> +sections is also syntactically allowed in +<code class="directive"><a href="./mod/core.html#directorymatch"><DirectoryMatch></a></code>, +<code class="directive"><a href="./mod/core.html#files"><Files></a></code>, +<code class="directive"><a href="./mod/core.html#filesmatch"><FilesMatch></a></code>, +<code class="directive"><a href="./mod/core.html#location"><Location></a></code>, +<code class="directive"><a href="./mod/core.html#locationmatch"><LocationMatch></a></code>, +<code class="directive"><a href="./mod/mod_proxy.html#proxy"><Proxy></a></code>, +and <code class="directive"><a href="./mod/mod_proxy.html#proxymatch"><ProxyMatch></a></code> +sections. There are some exceptions, however:</p> + +<ul> +<li>The <code class="directive"><a href="./mod/core.html#allowoverride">AllowOverride</a></code> directive +works only in <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> +sections.</li> + +<li>The <code>FollowSymLinks</code> and +<code>SymLinksIfOwnerMatch</code> <code class="directive"><a href="./mod/core.html#options">Options</a></code> work only in <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> sections or +<code>.htaccess</code> files.</li> + +<li>The <code class="directive"><a href="./mod/core.html#options">Options</a></code> directive cannot +be used in <code class="directive"><a href="./mod/core.html#files"><Files></a></code> +and <code class="directive"><a href="./mod/core.html#filesmatch"><FilesMatch></a></code> +sections.</li> +</ul> +</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div> +<div class="section"> +<h2><a name="merging" id="merging">How the sections are merged</a></h2> + +<p>The configuration sections are applied in a very particular order. +Since this can have important effects on how configuration directives +are interpreted, it is important to understand how this works.</p> + + <p>The order of merging is:</p> + + <ol> + <li> <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> (except regular expressions) + and <code>.htaccess</code> done simultaneously (with + <code>.htaccess</code>, if allowed, overriding + <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code>)</li> + + <li><code class="directive"><a href="./mod/core.html#directorymatch"><DirectoryMatch></a></code> + (and <code><Directory "~"></code>)</li> + + <li><code class="directive"><a href="./mod/core.html#files"><Files></a></code> and <code class="directive"><a href="./mod/core.html#filesmatch"><FilesMatch></a></code> done + simultaneously</li> + + <li><code class="directive"><a href="./mod/core.html#location"><Location></a></code> + and <code class="directive"><a href="./mod/core.html#locationmatch"><LocationMatch></a></code> done simultaneously</li> + + <li><code class="directive"><a href="./mod/core.html#if"><If></a></code> sections, even when + they are enclosed in any of the preceding contexts. + </li> + + </ol> + + <p>Some important remarks:</p> + <ul> + <li>Apart from <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code>, within each group the sections are + processed in the order they appear in the configuration files. + For example, a request for <em>/foo/bar</em> will match + <code><Location "/foo/bar"></code> and + <code><Location "/foo"></code> (group 4 in this case): + both sections will be evaluated + but in the order they appear in the configuration files.</li> + <li><code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> + (group 1 above) is processed in the order shortest directory + component to longest. For example, + <code><Directory "/var/web/dir"></code> will be processed before + <code><Directory "/var/web/dir/subdir"></code>.</li> + <li>If multiple <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> sections apply + to the same directory they are processed in the configuration file + order.</li> + <li>Configurations included via the <code class="directive"><a href="./mod/core.html#include">Include</a></code> directive will be treated as if + they were inside the including file at the location of the + <code class="directive"><a href="./mod/core.html#include">Include</a></code> directive.</li> + <li>Sections inside <code class="directive"><a href="./mod/core.html#virtualhost"><VirtualHost></a></code> sections + are applied <em>after</em> the corresponding sections outside + the virtual host definition. This allows virtual hosts to + override the main server configuration.</li> + <li>When the request is served by <code class="module"><a href="./mod/mod_proxy.html">mod_proxy</a></code>, the + <code class="directive"><a href="./mod/mod_proxy.html#proxy"><Proxy></a></code> + container takes the place of the <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> container in the processing + order.</li> + <li> Caution should be exercised when mixing related configuration + directives inside and outside of <code class="directive"><a href="./mod/core.html#if"><If></a></code> because of the effect on merging order. Explicit use + of <code class="directive"><a href="./mod/core.html#else"><Else></a></code> can help. + </li> + <li> When <code class="directive"><a href="./mod/core.html#if"><If></a></code> is + used in <code>.htaccess</code>, the enclosed directives in a parent + directory will be merged <em>after</em> non-enclosed directives in a + subdirectory.</li> + </ul> + + <div class="note"><h3>Technical Note</h3> + There is actually a + <code><Location></code>/<code><LocationMatch></code> + sequence performed just before the name translation phase + (where <code>Aliases</code> and <code>DocumentRoots</code> + are used to map URLs to filenames). The results of this + sequence are completely thrown away after the translation has + completed. + </div> + +<h3><a name="relationship-module-configuration" id="relationship-module-configuration">Relationship between modules and configuration sections</a></h3> + <p>One question that often arises after reading how configuration sections are + merged is related to how and when directives of specific modules like <code class="module"><a href="./mod/mod_rewrite.html">mod_rewrite</a></code> + are processed. The answer is not trivial and needs a bit of background. + Each httpd module manages its own configuration, and each of its directives in httpd.conf specify one piece + of configuration in a particular context. httpd does not execute a command as it is read.</p> + <p>At runtime, the core of httpd iterates over the defined configuration sections in the order + described above to determine which ones apply to the current request. When the first section matches, + it is considered the current configuration for this request. If a subsequent section matches too, + then each module with a directive in either of the sections is given a chance to merge its configuration between the two sections. The result is a third configuration, and the process goes on until all the configuration sections + are evaluated.</p> + <p>After the above step, the "real" processing of the HTTP request begins: each module has a chance to run + and perform whatever tasks they like. They can retrieve their own final merged configuration from the core + of the httpd to determine how they should act.</p> + <p>An example can help to visualize the whole process. The following configuration uses the + <code class="directive"><a href="./mod/mod_headers.html#header">Header</a></code> directive of <code class="module"><a href="./mod/mod_headers.html">mod_headers</a></code> to set + a specific HTTP header. What value will httpd set in the <code>CustomHeaderName</code> header for a request to + <code>/example/index.html</code> ? + </p> + <pre class="prettyprint lang-config"><Directory "/"> + Header set CustomHeaderName one + <FilesMatch ".*"> + Header set CustomHeaderName three + </FilesMatch> +</Directory> + +<Directory "/example"> + Header set CustomHeaderName two +</Directory></pre> + + <ul> + <li><code class="directive">Directory</code> "/" matches and an initial configuration to set the <code>CustomHeaderName</code> header with the value <code>one</code> is created.</li> + <li><code class="directive">Directory</code> "/example" matches, and since <code class="module"><a href="./mod/mod_headers.html">mod_headers</a></code> specifies in its code to override in case of a merge, a new configuration is created to set the <code>CustomHeaderName</code> header with the value <code>two</code>.</li> + <li><code class="directive">FilesMatch</code> ".*" matches and another merge opportunity arises, causing the <code>CustomHeaderName</code> header to be set with the value <code>three</code>.</li> + <li>Eventually during the next steps of the HTTP request processing <code class="module"><a href="./mod/mod_headers.html">mod_headers</a></code> will be called and it will receive the configuration to set the <code>CustomHeaderName</code> header with the value <code>three</code>. <code class="module"><a href="./mod/mod_headers.html">mod_headers</a></code> normally uses this configuration to perform its job, namely setting the foo header. This does not mean that a module can't perform a more complex action like discarding directives because not needed or deprecated, etc..</li> + </ul> + + <p>This is true for .htaccess too since they have the same priority as <code class="directive">Directory</code> in the merge order. The important concept to understand is that configuration sections like <code class="directive">Directory</code> and <code class="directive">FilesMatch</code> are not comparable to module specific directives like <code class="directive"><a href="./mod/mod_headers.html#header">Header</a></code> or <code class="directive"><a href="./mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> because they operate on different levels. + </p> + + +<h3><a name="merge-examples" id="merge-examples">Some useful examples</a></h3> + +<p>Below is an artificial example to show the order of +merging. Assuming they all apply to the request, the directives in +this example will be applied in the order A > B > C > D > +E.</p> + +<pre class="prettyprint lang-config"><Location "/"> + E +</Location> + +<Files "f.html"> + D +</Files> + +<VirtualHost *> + <Directory "/a/b"> + B + </Directory> +</VirtualHost> + +<DirectoryMatch "^.*b$"> + C +</DirectoryMatch> + +<Directory "/a/b"> + A +</Directory></pre> + + + +<p>For a more concrete example, consider the following. Regardless of +any access restrictions placed in <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> sections, the <code class="directive"><a href="./mod/core.html#location"><Location></a></code> section will be +evaluated last and will allow unrestricted access to the server. In +other words, order of merging is important, so be careful!</p> + +<pre class="prettyprint lang-config"><Location "/"> + Require all granted +</Location> + +# Whoops! This <Directory> section will have no effect +<Directory "/"> + <RequireAll> + Require all granted + Require not host badguy.example.com + </RequireAll> +</Directory></pre> + + + + +</div></div> +<div class="bottomlang"> +<p><span>Available Languages: </span><a href="./en/sections.html" title="English"> en </a> | +<a href="./fr/sections.html" hreflang="fr" rel="alternate" title="Français"> fr </a> | +<a href="./ja/sections.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | +<a href="./ko/sections.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> | +<a href="./tr/sections.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p> +</div><div class="top"><a href="#page-header"><img src="./images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. 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