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| <p class="apache">Apache HTTP Server Version 2.0</p> |
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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 2.0</a> > <a href="./">Virtual Hosts</a></div><div id="page-content"><div class="retired"><h4>Please note</h4> |
| <p>This document refers to the <strong>2.0</strong> version of Apache httpd, which <strong>is no longer maintained</strong>. Upgrade, and refer to the current version of httpd instead, documented at:</p> |
| <ul><li><a href="http://httpd.apache.org/docs/current/">Current release version of Apache HTTP Server documentation</a></li></ul><p>You may follow <a href="http://httpd.apache.org/docs/current/vhosts/mass.html">this link</a> to go to the current version of this document.</p></div><div id="preamble"><h1>Dynamically Configured Mass Virtual Hosting</h1> |
| <div class="toplang"> |
| <p><span>Available Languages: </span><a href="../en/vhosts/mass.html" title="English"> en </a> | |
| <a href="../ko/vhosts/mass.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> | |
| <a href="../tr/vhosts/mass.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p> |
| </div> |
| |
| |
| <p>This document describes how to efficiently serve an |
| arbitrary number of virtual hosts with the Apache httpd webserver. |
| </p> |
| |
| </div> |
| <div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#motivation">Motivation</a></li> |
| <li><img alt="" src="../images/down.gif" /> <a href="#overview">Overview</a></li> |
| <li><img alt="" src="../images/down.gif" /> <a href="#simple">Simple Dynamic Virtual Hosts</a></li> |
| <li><img alt="" src="../images/down.gif" /> <a href="#homepages">A Virtually Hosted Homepages System</a></li> |
| <li><img alt="" src="../images/down.gif" /> <a href="#combinations">Using Multiple Virtual |
| Hosting Systems on the Same Server</a></li> |
| <li><img alt="" src="../images/down.gif" /> <a href="#ipbased">More Efficient IP-Based Virtual Hosting</a></li> |
| <li><img alt="" src="../images/down.gif" /> <a href="#simple.rewrite">Simple 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="#homepages.rewrite">A |
| Homepages System Using <code>mod_rewrite</code></a></li> |
| <li><img alt="" src="../images/down.gif" /> <a href="#xtra-conf">Using a Separate Virtual |
| Host Configuration File</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="motivation" id="motivation">Motivation</a></h2> |
| |
| <p>The techniques described here are of interest if your |
| <code>httpd.conf</code> contains many |
| <code><VirtualHost></code> sections that are |
| substantially the same, for example:</p> |
| |
| <div class="example"><p><code> |
| NameVirtualHost 111.22.33.44<br /> |
| <VirtualHost 111.22.33.44><br /> |
| <span class="indent"> |
| ServerName www.customer-1.com<br /> |
| DocumentRoot /www/hosts/www.customer-1.com/docs<br /> |
| ScriptAlias /cgi-bin/ /www/hosts/www.customer-1.com/cgi-bin<br /> |
| </span> |
| </VirtualHost><br /> |
| <VirtualHost 111.22.33.44><br /> |
| <span class="indent"> |
| ServerName www.customer-2.com<br /> |
| DocumentRoot /www/hosts/www.customer-2.com/docs<br /> |
| ScriptAlias /cgi-bin/ /www/hosts/www.customer-2.com/cgi-bin<br /> |
| </span> |
| </VirtualHost><br /> |
| # blah blah blah<br /> |
| <VirtualHost 111.22.33.44><br /> |
| <span class="indent"> |
| ServerName www.customer-N.com<br /> |
| DocumentRoot /www/hosts/www.customer-N.com/docs<br /> |
| ScriptAlias /cgi-bin/ /www/hosts/www.customer-N.com/cgi-bin<br /> |
| </span> |
| </VirtualHost> |
| </code></p></div> |
| |
| <p>The basic idea is to replace all of the static |
| <code><VirtualHost></code> configurations with a mechanism |
| that works them out dynamically. This has a number of |
| advantages:</p> |
| |
| <ol> |
| <li>Your configuration file is smaller, so Apache starts |
| more quickly and uses less memory.</li> |
| |
| <li>Adding virtual hosts is simply a matter of creating the |
| appropriate directories in the filesystem and entries in the |
| DNS - you don't need to reconfigure or restart Apache.</li> |
| </ol> |
| |
| <p>The main disadvantage is that you cannot have a different log file for |
| each virtual host; however, if you have many virtual hosts, doing |
| this can be a bad idea anyway, because of the number of file |
| descriptors needed. It is better to log to a pipe or a fifo, and arrange for |
| the process at the other end to distribute the logs to the customers. |
| (This can also be used to accumulate statistics, etc.).</p> |
| |
| </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> |
| <div class="section"> |
| <h2><a name="overview" id="overview">Overview</a></h2> |
| |
| <p>A virtual host is defined by two pieces of information: its |
| IP address, and the contents of the <code>Host:</code> header |
| in the HTTP request. The dynamic mass virtual hosting technique |
| used here is based on automatically inserting this information into the |
| pathname of the file that is used to satisfy the request. This |
| can be most easily done by using <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> |
| with Apache 2.0. Alternatively, <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> can be used. |
| Both of these modules are disabled by default; you must enable |
| one of them when configuring and building Apache if you want to |
| use this technique.</p> |
| |
| <p>A couple of things need to be `faked' to make the dynamic |
| virtual host look like a normal one. The most important is the |
| server name, which is used by Apache to generate |
| self-referential URLs etc. It is configured with the |
| <code>ServerName</code> directive, and it is available to CGIs |
| via the <code>SERVER_NAME</code> environment variable. The |
| actual value used at run time is controlled by the <code class="directive"><a href="../mod/core.html#usecanonicalname">UseCanonicalName</a></code> |
| setting. With <code>UseCanonicalName Off</code>, the server name |
| is taken from the contents of the <code>Host:</code> header in the |
| request. With <code>UseCanonicalName DNS</code>, it is taken from a |
| reverse DNS lookup of the virtual host's IP address. The former |
| setting is used for name-based dynamic virtual hosting, and the |
| latter is used for IP-based hosting. If Apache cannot work out |
| the server name because there is no <code>Host:</code> header, |
| or the DNS lookup fails, then the value configured with |
| <code>ServerName</code> is used instead.</p> |
| |
| <p>The other thing to `fake' is the document root (configured |
| with <code>DocumentRoot</code> and available to CGIs via the |
| <code>DOCUMENT_ROOT</code> environment variable). In a normal |
| configuration, this is used by the core module when |
| mapping URIs to filenames, but when the server is configured to |
| do dynamic virtual hosting, that job must be taken over by another |
| module (either <code>mod_vhost_alias</code> or |
| <code>mod_rewrite</code>), which has a different way of doing |
| the mapping. Neither of these modules is responsible for |
| setting the <code>DOCUMENT_ROOT</code> environment variable so |
| if any CGIs or SSI documents make use of it, they will get a |
| misleading value.</p> |
| |
| </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> |
| <div class="section"> |
| <h2><a name="simple" id="simple">Simple Dynamic Virtual Hosts</a></h2> |
| |
| <p>This extract from <code>httpd.conf</code> implements the |
| virtual host arrangement outlined in the <a href="#motivation">Motivation</a> section above, but in a |
| generic fashion using <code>mod_vhost_alias</code>.</p> |
| |
| <div class="example"><p><code> |
| # get the server name from the Host: header<br /> |
| UseCanonicalName Off<br /> |
| <br /> |
| # this log format can be split per-virtual-host based on the first field<br /> |
| LogFormat "%V %h %l %u %t \"%r\" %s %b" vcommon<br /> |
| CustomLog logs/access_log vcommon<br /> |
| <br /> |
| # include the server name in the filenames used to satisfy requests<br /> |
| VirtualDocumentRoot /www/hosts/%0/docs<br /> |
| VirtualScriptAlias /www/hosts/%0/cgi-bin |
| </code></p></div> |
| |
| <p>This configuration can be changed into an IP-based virtual |
| hosting solution by just turning <code>UseCanonicalName |
| Off</code> into <code>UseCanonicalName DNS</code>. The server |
| name that is inserted into the filename is then derived from |
| the IP address of the virtual host.</p> |
| |
| </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> |
| <div class="section"> |
| <h2><a name="homepages" id="homepages">A Virtually Hosted Homepages System</a></h2> |
| |
| <p>This is an adjustment of the above system, tailored for an |
| ISP's homepages server. Using a slightly more complicated |
| configuration, we can select substrings of the server name to |
| use in the filename so that, for example, the documents for |
| <code>www.user.isp.com</code> are found in |
| <code>/home/user/</code>. It uses a single <code>cgi-bin</code> |
| directory instead of one per virtual host.</p> |
| |
| <div class="example"><p><code> |
| # all the preliminary stuff is the same as above, then<br /> |
| <br /> |
| # include part of the server name in the filenames<br /> |
| VirtualDocumentRoot /www/hosts/%2/docs<br /> |
| <br /> |
| # single cgi-bin directory<br /> |
| ScriptAlias /cgi-bin/ /www/std-cgi/<br /> |
| </code></p></div> |
| |
| <p>There are examples of more complicated |
| <code>VirtualDocumentRoot</code> settings in the |
| <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> documentation.</p> |
| |
| </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> |
| <div class="section"> |
| <h2><a name="combinations" id="combinations">Using Multiple Virtual |
| Hosting Systems on the Same Server</a></h2> |
| |
| <p>With more complicated setups, you can use Apache's normal |
| <code><VirtualHost></code> directives to control the |
| scope of the various virtual hosting configurations. For |
| example, you could have one IP address for general customers' homepages, |
| and another for commercial customers, with the following setup. |
| This can, of course, be combined with conventional |
| <code><VirtualHost></code> configuration sections.</p> |
| |
| <div class="example"><p><code> |
| UseCanonicalName Off<br /> |
| <br /> |
| LogFormat "%V %h %l %u %t \"%r\" %s %b" vcommon<br /> |
| <br /> |
| <Directory /www/commercial><br /> |
| <span class="indent"> |
| Options FollowSymLinks<br /> |
| AllowOverride All<br /> |
| </span> |
| </Directory><br /> |
| <br /> |
| <Directory /www/homepages><br /> |
| <span class="indent"> |
| Options FollowSymLinks<br /> |
| AllowOverride None<br /> |
| </span> |
| </Directory><br /> |
| <br /> |
| <VirtualHost 111.22.33.44><br /> |
| <span class="indent"> |
| ServerName www.commercial.isp.com<br /> |
| <br /> |
| CustomLog logs/access_log.commercial vcommon<br /> |
| <br /> |
| VirtualDocumentRoot /www/commercial/%0/docs<br /> |
| VirtualScriptAlias /www/commercial/%0/cgi-bin<br /> |
| </span> |
| </VirtualHost><br /> |
| <br /> |
| <VirtualHost 111.22.33.45><br /> |
| <span class="indent"> |
| ServerName www.homepages.isp.com<br /> |
| <br /> |
| CustomLog logs/access_log.homepages vcommon<br /> |
| <br /> |
| VirtualDocumentRoot /www/homepages/%0/docs<br /> |
| ScriptAlias /cgi-bin/ /www/std-cgi/<br /> |
| </span> |
| </VirtualHost> |
| </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="ipbased" id="ipbased">More Efficient IP-Based Virtual Hosting</a></h2> |
| |
| <p>The configuration changes suggested to turn <a href="#simple">the first |
| example</a> into an IP-based virtual hosting setup result in |
| a rather inefficient setup. A new DNS lookup is required for every |
| request. To avoid this overhead, the filesystem can be arranged to |
| correspond to the IP addresses, instead of to the host names, thereby |
| negating the need for a DNS lookup. Logging will also have to be adjusted |
| to fit this system.</p> |
| |
| <div class="example"><p><code> |
| # get the server name from the reverse DNS of the IP address<br /> |
| UseCanonicalName DNS<br /> |
| <br /> |
| # include the IP address in the logs so they may be split<br /> |
| LogFormat "%A %h %l %u %t \"%r\" %s %b" vcommon<br /> |
| CustomLog logs/access_log vcommon<br /> |
| <br /> |
| # include the IP address in the filenames<br /> |
| VirtualDocumentRootIP /www/hosts/%0/docs<br /> |
| VirtualScriptAliasIP /www/hosts/%0/cgi-bin<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="simple.rewrite" id="simple.rewrite">Simple 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>There are a couple of especially tricky bits: by default, |
| <code>mod_rewrite</code> runs before other URI translation |
| modules (<code>mod_alias</code> etc.) - so if you wish to use these modules, <code>mod_rewrite</code> must be configured to accommodate |
| them. Also, some magic is required to do a |
| per-dynamic-virtual-host equivalent of |
| <code>ScriptAlias</code>.</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 /> |
| # now for the hard bit<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/$1<br /> |
| <br /> |
| ## and now deal with CGIs - we have to force a MIME type<br /> |
| RewriteCond %{REQUEST_URI} ^/cgi-bin/<br /> |
| RewriteRule ^/(.*)$ /www/hosts/${lowercase:%{SERVER_NAME}}/cgi-bin/$1 [T=application/x-httpd-cgi]<br /> |
| <br /> |
| # that's it! |
| </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="homepages.rewrite" id="homepages.rewrite">A |
| Homepages System Using <code>mod_rewrite</code></a></h2> |
| |
| <p>This does the same thing as <a href="#homepages">the second |
| example</a>.</p> |
| |
| <div class="example"><p><code> |
| RewriteEngine on<br /> |
| <br /> |
| RewriteMap lowercase int:tolower<br /> |
| <br /> |
| # allow CGIs to work<br /> |
| RewriteCond %{REQUEST_URI} !^/cgi-bin/<br /> |
| <br /> |
| # check the hostname is right so that the RewriteRule works<br /> |
| RewriteCond ${lowercase:%{SERVER_NAME}} ^www\.[a-z-]+\.isp\.com$<br /> |
| <br /> |
| # concatenate the virtual host name onto the start of the URI<br /> |
| # the [C] means do the next rewrite on the result of this one<br /> |
| RewriteRule ^(.+) ${lowercase:%{SERVER_NAME}}$1 [C]<br /> |
| <br /> |
| # now create the real file name<br /> |
| RewriteRule ^www\.([a-z-]+)\.isp\.com/(.*) /home/$1/$2<br /> |
| <br /> |
| # define the global CGI directory<br /> |
| ScriptAlias /cgi-bin/ /www/std-cgi/ |
| </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> |
| www.customer-1.com /www/customers/1<br /> |
| www.customer-2.com /www/customers/2<br /> |
| # ...<br /> |
| www.customer-N.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 [T=application/x-httpd-cgi] |
| </code></p></div> |
| |
| </div></div> |
| <div class="bottomlang"> |
| <p><span>Available Languages: </span><a href="../en/vhosts/mass.html" title="English"> en </a> | |
| <a href="../ko/vhosts/mass.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> | |
| <a href="../tr/vhosts/mass.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p> |
| </div><div id="footer"> |
| <p class="apache">Copyright 2013 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p> |
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