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<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 2.2</a> > <a href="./">Rewrite</a></div><div id="page-content"><div id="preamble"><h1>Dynamic mass virtual hosts with mod_rewrite</h1>
<div class="toplang">
<p><span>Available Languages: </span><a href="../en/rewrite/vhosts.html" title="English"> en </a></p>
</div>
<p>This document supplements the <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>
<a href="../mod/mod_rewrite.html">reference documentation</a>. It describes
how you can use <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> to create dynamically
configured virtual hosts.</p>
<div class="warning">mod_rewrite is not the best way to configure
virtual hosts. You should first consider the <a href="../vhosts/mass.html">alternatives</a> before resorting to
mod_rewrite. See also the "<a href="avoid.html#vhosts">how to avoid
mod_rewrite</a> document.</div>
</div>
<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#per-hostname">Virtual Hosts For Arbitrary Hostnames</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#simple.rewrite">Dynamic
Virtual Hosts Using <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code></a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#xtra-conf">Using a Separate Virtual Host Configuration File</a></li>
</ul><h3>See also</h3><ul class="seealso"><li><a href="../mod/mod_rewrite.html">Module documentation</a></li><li><a href="intro.html">mod_rewrite introduction</a></li><li><a href="remapping.html">Redirection and remapping</a></li><li><a href="access.html">Controlling access</a></li><li><a href="proxy.html">Proxying</a></li><li><a href="rewritemap.html">RewriteMap</a></li><li><a href="advanced.html">Advanced techniques and tricks</a></li><li><a href="avoid.html">When not to use mod_rewrite</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="per-hostname" id="per-hostname">Virtual Hosts For Arbitrary Hostnames</a></h2>
<dl>
<dt>Description:</dt>
<dd>
<p>We want to automatically create a virtual host for every hostname
which resolves in our domain, without having to create
new VirtualHost sections.</p>
<p>In this recipe, we assume that we'll be using the hostname
<code>www.<strong>SITE</strong>.example.com</code> for each
user, and serve their content out of
<code>/home/<strong>SITE</strong>/www</code>.</p>
</dd>
<dt>Solution:</dt>
<dd>
<div class="example"><p><code>
RewriteEngine on<br />
<br />
RewriteMap lowercase int:tolower<br />
<br />
RewriteCond %{lowercase:%{<strong>HTTP_HOST</strong>}} ^www\.<strong>([^.]+)</strong>\.example\.com$<br />
RewriteRule ^(.*) /home/<strong>%1</strong>/www$1
</code></p></div></dd>
<dt>Discussion</dt>
<dd>
<div class="warning">You will need to take care of the DNS
resolution - Apache does
not handle name resolution. You'll need either to create CNAME
records for each hostname, or a DNS wildcard record. Creating DNS
records is beyond the scope of this document.</div>
<p>The internal <code>tolower</code> RewriteMap directive is used to
ensure that the hostnames being used are all lowercase, so that there is
no ambiguity in the directory structure which must be created.</p>
<p>Parentheses used in a <code class="directive"><a href="../mod/mod_rewrite.html#rewritecond">RewriteCond</a></code> are captured into the
backreferences <code>%1</code>, <code>%2</code>, etc, while parentheses
used in <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> are
captured into the backreferences <code>$1</code>, <code>$2</code>,
etc.</p>
<p>
As with many techniques discussed in this document, mod_rewrite really
isn't the best way to accomplish this task. You should, instead,
consider using <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> instead, as it will much
more gracefully handle anything beyond serving static files, such as any
dynamic content, and Alias resolution.
</p>
</dd>
</dl>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="simple.rewrite" id="simple.rewrite">Dynamic
Virtual Hosts Using <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code></a></h2>
<p>This extract from <code>httpd.conf</code> does the same
thing as <a href="#simple">the first example</a>. The first
half is very similar to the corresponding part above, except for
some changes, required for backward compatibility and to make the
<code>mod_rewrite</code> part work properly; the second half
configures <code>mod_rewrite</code> to do the actual work.</p>
<p>Because <code>mod_rewrite</code> runs before other URI translation
modules (e.g., <code>mod_alias</code>), <code>mod_rewrite</code> must
be told to explicitly ignore any URLs that would have been handled
by those modules. And, because these rules would otherwise bypass
any <code>ScriptAlias</code> directives, we must have
<code>mod_rewrite</code> explicitly enact those mappings.</p>
<div class="example"><p><code>
# get the server name from the Host: header<br />
UseCanonicalName Off<br />
<br />
# splittable logs<br />
LogFormat "%{Host}i %h %l %u %t \"%r\" %s %b" vcommon<br />
CustomLog logs/access_log vcommon<br />
<br />
<Directory /www/hosts><br />
<span class="indent">
# ExecCGI is needed here because we can't force<br />
# CGI execution in the way that ScriptAlias does<br />
Options FollowSymLinks ExecCGI<br />
</span>
</Directory><br />
<br />
RewriteEngine On<br />
<br />
# a ServerName derived from a Host: header may be any case at all<br />
RewriteMap lowercase int:tolower<br />
<br />
## deal with normal documents first:<br />
# allow Alias /icons/ to work - repeat for other aliases<br />
RewriteCond %{REQUEST_URI} !^/icons/<br />
# allow CGIs to work<br />
RewriteCond %{REQUEST_URI} !^/cgi-bin/<br />
# do the magic<br />
RewriteRule ^/(.*)$ /www/hosts/${lowercase:%{SERVER_NAME}}/docs/$1<br />
<br />
## and now deal with CGIs - we have to force a handler<br />
RewriteCond %{REQUEST_URI} ^/cgi-bin/<br />
RewriteRule ^/(.*)$ /www/hosts/${lowercase:%{SERVER_NAME}}/cgi-bin/$1 [H=cgi-script]<br />
</code></p></div>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="xtra-conf" id="xtra-conf">Using a Separate Virtual Host Configuration File</a></h2>
<p>This arrangement uses more advanced <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>
features to work out the translation from virtual host to document
root, from a separate configuration file. This provides more
flexibility, but requires more complicated configuration.</p>
<p>The <code>vhost.map</code> file should look something like
this:</p>
<div class="example"><p><code>
customer-1.example.com /www/customers/1<br />
customer-2.example.com /www/customers/2<br />
# ...<br />
customer-N.example.com /www/customers/N<br />
</code></p></div>
<p>The <code>httpd.conf</code> should contain the following:</p>
<div class="example"><p><code>
RewriteEngine on<br />
<br />
RewriteMap lowercase int:tolower<br />
<br />
# define the map file<br />
RewriteMap vhost txt:/www/conf/vhost.map<br />
<br />
# deal with aliases as above<br />
RewriteCond %{REQUEST_URI} !^/icons/<br />
RewriteCond %{REQUEST_URI} !^/cgi-bin/<br />
RewriteCond ${lowercase:%{SERVER_NAME}} ^(.+)$<br />
# this does the file-based remap<br />
RewriteCond ${vhost:%1} ^(/.*)$<br />
RewriteRule ^/(.*)$ %1/docs/$1<br />
<br />
RewriteCond %{REQUEST_URI} ^/cgi-bin/<br />
RewriteCond ${lowercase:%{SERVER_NAME}} ^(.+)$<br />
RewriteCond ${vhost:%1} ^(/.*)$<br />
RewriteRule ^/(.*)$ %1/cgi-bin/$1 [H=cgi-script]
</code></p></div>
</div></div>
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