docs/manual/rewrite/proxy.xml

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<manualpage metafile="proxy.xml.meta">
  <parentdocument href="./">Rewrite</parentdocument>

<title>Using mod_rewrite for Proxying</title>

<summary>

<p>This document supplements the <module>mod_rewrite</module> 
<a href="../mod/mod_rewrite.html">reference documentation</a>. It describes
how to use the RewriteRule's [P] flag to proxy content to another server.
A number of recipes are provided that describe common scenarios.</p>

</summary>
<seealso><a href="../mod/mod_rewrite.html">Module documentation</a></seealso>
<seealso><a href="intro.html">mod_rewrite introduction</a></seealso>
<seealso><a href="remapping.html">Redirection and remapping</a></seealso>
<seealso><a href="access.html">Controlling access</a></seealso>
<seealso><a href="vhosts.html">Virtual hosts</a></seealso>
<!--<seealso><a href="proxy.html">Proxying</a></seealso>-->
<seealso><a href="rewritemap.html">Using RewriteMap</a></seealso>
<seealso><a href="advanced.html">Advanced techniques and tricks</a></seealso>
<seealso><a href="avoid.html">When not to use mod_rewrite</a></seealso>

<section id="dynamic-proxy">

  <title>Proxying Content with mod_rewrite</title>

  <dl>
    <dt>Description:</dt>

    <dd>
    <p>
    mod_rewrite provides the [P] flag, which allows URLs to be passed,
    via mod_proxy, to another server. Two examples are given here. In
    one example, a URL is passed directly to another server, and served
    as though it were a local URL. In the other example, we proxy
    missing content to a back-end server.</p>
    </dd>

    <dt>Solution:</dt>

    <dd>
      <p>To simply map a URL to another server, we use the [P] flag, as
      follows:</p>

<example>
RewriteEngine  on<br />
RewriteBase    /products/<br />
RewriteRule    ^<strong>widget/</strong>(.*)$  <strong>http://product.example.com/widget/</strong>$1  [<strong>P</strong>]<br />
ProxyPassReverse /products/widget/ http://product.example.com/widget/
</example>

   <p>In the second example, we proxy the request only if we can't find
   the resource locally. This can be very useful when you're migrating
   from one server to another, and you're not sure if all the content
   has been migrated yet.</p>

<example>
RewriteCond %{REQUEST_FILENAME}       <strong>!-f</strong><br />
RewriteCond %{REQUEST_FILENAME}       <strong>!-d</strong><br />
RewriteRule ^/(.*) http://<strong>old</strong>.example.com/$1 [<strong>P</strong>]<br />
ProxyPassReverse / http://old.example.com/
</example>
    </dd>

    <dt>Discussion:</dt>

    <dd><p>In each case, we add a <directive
    module="mod_proxy">ProxyPassReverse</directive> directive to ensure
    that any redirects issued by the backend are correctly passed on to
    the client.</p>
    
    <p>Consider using either <directive
    module="mod_proxy">ProxyPass</directive> or <directive
    module="mod_proxy">ProxyPassMatch</directive> whenever possible in
    preference to mod_rewrite.</p>
    </dd>
  </dl>

</section>

</manualpage>