apache/docs/manual/mod/mod_proxy_express.xml

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<modulesynopsis metafile="mod_proxy_express.xml.meta">

<name>mod_proxy_express</name>
<description>Dynamic mass reverse proxy extension for
<module>mod_proxy</module></description>
<status>Extension</status>
<sourcefile>mod_proxy_express.c</sourcefile>
<identifier>proxy_express_module</identifier>

<summary>
    <p>This module creates dynamically configured mass reverse
    proxies, by mapping the Host: header of the HTTP request to
    a server name and backend URL stored in a DBM file.
    This allows for easy use of a huge number of reverse proxies
    with no configuration changes. It is much less feature-full
    than <module>mod_proxy_balancer</module>, which also provides
    dynamic growth, but is intended to handle much, much
    larger numbers of backends. It is ideally suited as a
    front-end HTTP switch.</p>

    <p>This module <em>requires</em> the service of <module
    >mod_proxy</module>.</p>

    <note type="warning"><title>Warning</title>
      <p>Do not enable proxying until you have <a
      href="mod_proxy.html#access">secured your server</a>. Open proxy
      servers are dangerous both to your network and to the Internet at
      large.</p>
    </note>

<note><title>Limitations</title>
  <ul>
    <li>This module is not intended to replace the dynamic capability of
      <module>mod_proxy_balancer</module>. Instead, it is intended to be mostly
      a lightweight and fast alternative to using <module>mod_rewrite</module>
      with <directive>RewriteMap</directive> and the <code>[P]</code> flag
      for mapped reverse proxying.
    </li>
    <li>It does not support regex or pattern matching at all.
    </li>
    <li>It emulates:
      <example>
        ProxyPass / backend.server:port<br />
        ProxyPassReverse / backend.server:port<br />
      </example>
      That is, the entire URL is appended to the mapped backend
      URL. This is in keeping with the intent of being a simple
      but fast reverse proxy switch.
    </li>
  </ul>
</note>

</summary>
<seealso><module>mod_proxy</module></seealso>

<directivesynopsis>
<name>ProxyExpressEnable</name>
<description>Enable the module functionality.</description>
<syntax>ProxyExpressEnable [on|off]</syntax>
<default>off</default>
<contextlist><context>server config</context><context>virtual host</context>
  </contextlist>
<compatibility>Available in Apache 2.3.13 and later</compatibility>

<usage>
  <p>The <directive>ProxyExpressEnable</directive> directive
    controls whether the module will be active.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>ProxyExpressDBMFile</name>
<description>Pathname to DBM file.</description>
<syntax>ProxyExpressDBMFile &lt;pathname&gt;</syntax>
<default>None</default>
<contextlist><context>server config</context><context>virtual host</context>
  </contextlist>
<compatibility>Available in Apache 2.3.13 and later</compatibility>

<usage>
  <p>The <directive>ProxyExpressDBMFile</directive> directive
    points to the location of the Express map DBM file. This
    file serves to map the incoming server name, obtained from
    the Host: header, to a backend URL.</p>

    <note><title>Note</title>
      <p>The file is constructed from a plain text file format using
        the <code><a href="../programs/httxt2dbm.html">httxt2dbm</a></code>
        utility.</p>

      <example><title>ProxyExpress map file</title>
        ##<br />
        ##express-map.txt:<br />
        ##<br />
        <br />
        www1.example.com    http://192.168.211.2:8080<br />
        www2.example.com   http://192.168.211.12:8088<br />
        www3.example.com   http://192.168.212.10<br />
      </example>

      <example><title>Create DBM file</title>
        httxt2dbm -i express-map.txt -o emap<br />
        </example>

      <example><title>Configuration</title>
        ProxyExpressDBMFile emap<br />
        </example>
    </note>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>ProxyExpressDBMType</name>
<description>DBM type of file.</description>
<syntax>ProxyExpressDBMFile &lt;type&gt;</syntax>
<default>"default"</default>
<contextlist><context>server config</context><context>virtual host</context>
  </contextlist>
<compatibility>Available in Apache 2.3.13 and later</compatibility>

<usage>
  <p>The <directive>ProxyExpressDBMType</directive> directive
    controls the DBM type expected by the module. The default
    is the default DBM type created with <code>
    <a href="../programs/httxt2dbm.html">httxt2dbm</a></code>.</p>
    <p>Possible values are (not all may be available at run time):</p>
<table border="1" style="zebra">
    <columnspec><column width=".3"/><column width=".7"/></columnspec>

    <tr><th>Value</th><th>Description</th></tr>
    <tr><td><code>db</code></td><td> Berkeley DB files</td></tr>
    <tr><td><code>gdbm</code></td><td> GDBM files</td></tr>
    <tr><td><code>ndbm</code></td><td> NDBM files</td></tr>
    <tr><td><code>sdbm</code></td><td> SDBM files (always available)</td></tr>
    <tr><td><code>default</code></td><td> default DBM type</td></tr>
    </table>

</usage>
</directivesynopsis>

</modulesynopsis>