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 prevent the proxy server from being used to access the
-<code>www.example.com</code> website.</p>
+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 all granted
+ Require host yournetwork.example.com
</Proxy></pre>
</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
container takes the place of the <code class="directive"><a href="./mod/core.html#directory"><Directory></a></code> container in the processing
order.</p>
- <p>Later sections override earlier ones, however each module is responsible
- for interpreting what form this override takes. A later configuration section
- with directives from a given module might cause a conceptual "merge" of some
- directives, all directives, or a complete replacement of the modules
- configuration with the module defaults and directives explicitly listed in
- the later context.</p>
-
-<div class="note"><h3>Technical Note</h3>
+ <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
are used to map URLs to filenames). The results of this
sequence are completely thrown away after the translation has
completed.
-</div>
+ </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>
-<h3><a name="merge-examples" id="merge-examples">Some Examples</a></h3>
+<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 perfom 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
</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
projects / apache / commitdiff