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

<name>mod_vhost_alias</name>

<description>Provides for dynamically configured mass virtual

hosting</description>

<status>Extension</status>

<sourcefile>mod_vhost_alias.c</sourcefile>

<identifier>vhost_alias_module</identifier>

<summary>

<p>This module creates dynamically configured virtual hosts, by

allowing the IP address and/or the <code>Host:</code> header of

the HTTP request to be used as part of the pathname to

determine what files to serve. This allows for easy use of a

huge number of virtual hosts with similar configurations.</p>

<note><title>Note</title>

<p>If <module>mod_alias</module> or <module>mod_userdir</module> are

used for translating URIs to filenames, they will override the

directives of <module>mod_vhost_alias</module> described below. For

example, the following configuration will map <code>

/cgi-bin/script.pl</code> to <code>

/usr/local/apache2/cgi-bin/script.pl</code> in all cases:</p>

<example>

ScriptAlias /cgi-bin/ /usr/local/apache2/cgi-bin/<br />

VirtualScriptAlias /never/found/%0/cgi-bin/

</example>

</note>

</summary>

<seealso><directive module="core">UseCanonicalName</directive></seealso>

<seealso><a href="/vhosts/mass.html">Dynamically configured mass

virtual hosting</a></seealso>

<section id="interpol">

<title>Directory Name Interpolation</title>

<p>All the directives in this module interpolate a string into

a pathname. The interpolated string (henceforth called the

"name") may be either the server name (see the <directive

module="core">UseCanonicalName</directive>

directive for details on how this is determined) or the IP

address of the virtual host on the server in dotted-quad

format. The interpolation is controlled by specifiers inspired

by <code>printf</code> which have a number of formats:</p>

<table>

<columnspec><column width=".2"/><column width=".6"/></columnspec>

<tr><td><code>%%</code></td>

<td>insert a <code>%</code></td></tr>

<tr><td><code>%p</code></td>

<td>insert the port number of the virtual host</td></tr>

<tr><td><code>%N.M</code></td>

<td>insert (part of) the name</td></tr>

</table>

<p><code>N</code> and <code>M</code> are used to specify

substrings of the name. <code>N</code> selects from the

dot-separated components of the name, and <code>M</code>

selects characters within whatever <code>N</code> has selected.

<code>M</code> is optional and defaults to zero if it isn't

present; the dot must be present if and only if <code>M</code>

is present. The interpretation is as follows:</p>

<table>

<columnspec><column width=".1"/><column width=".4"/></columnspec>

<tr><td><code>0</code></td>

<td>the whole name</td></tr>

<tr><td><code>1</code></td>

<td>the first part</td></tr>

<tr><td><code>2</code></td>

<td>the second part</td></tr>

<tr><td><code>-1</code></td>

<td>the last part</td></tr>

<tr><td><code>-2</code></td>

<td>the penultimate part</td></tr>

<tr><td><code>2+</code></td>

<td>the second and all subsequent parts</td></tr>

<tr><td><code>-2+</code></td>

<td>the penultimate and all preceding parts</td></tr>

<tr><td><code>1+</code> and <code>-1+</code></td>

<td>the same as <code>0</code></td></tr>

</table>

<p>If <code>N</code> or <code>M</code> is greater than the number

of parts available a single underscore is interpolated. </p>

</section>

<section id="examples">

<title>Examples</title>

<p>For simple name-based virtual hosts you might use the

following directives in your server configuration file:</p>

<example>

UseCanonicalName Off<br />

VirtualDocumentRoot /usr/local/apache/vhosts/%0

</example>

<p>A request for

<code>http://www.example.com/directory/file.html</code> will be

satisfied by the file

<code>/usr/local/apache/vhosts/www.example.com/directory/file.html</code>.

</p>

<p>For a very large number of virtual hosts it is a good idea

to arrange the files to reduce the size of the

<code>vhosts</code> directory. To do this you might use the

following in your configuration file:</p>

<example>

UseCanonicalName Off<br />

VirtualDocumentRoot /usr/local/apache/vhosts/%3+/%2.1/%2.2/%2.3/%2

</example>

<p>A request for

<code>http://www.domain.example.com/directory/file.html</code>

will be satisfied by the file

<code>/usr/local/apache/vhosts/example.com/d/o/m/domain/directory/file.html</code>.</p>

<p>A more even spread of files can be achieved by hashing from the

end of the name, for example: </p>

<example>

VirtualDocumentRoot /usr/local/apache/vhosts/%3+/%2.-1/%2.-2/%2.-3/%2

</example>

<p>The example request would come from

<code>/usr/local/apache/vhosts/example.com/n/i/a/domain/directory/file.html</code>.</p>

<p>Alternatively you might use: </p>

<example>

VirtualDocumentRoot /usr/local/apache/vhosts/%3+/%2.1/%2.2/%2.3/%2.4+

</example>

<p>The example request would come from

<code>/usr/local/apache/vhosts/example.com/d/o/m/ain/directory/file.html</code>.</p>

<p>For IP-based virtual hosting you might use the following in

your configuration file:</p>

<example>

UseCanonicalName DNS<br />

VirtualDocumentRootIP /usr/local/apache/vhosts/%1/%2/%3/%4/docs<br />

VirtualScriptAliasIP /usr/local/apache/vhosts/%1/%2/%3/%4/cgi-bin

</example>

<p>A request for

<code>http://www.domain.example.com/directory/file.html</code>

would be satisfied by the file

<code>/usr/local/apache/vhosts/10/20/30/40/docs/directory/file.html</code>

if the IP address of <code>www.domain.example.com</code> were

10.20.30.40. A request for

<code>http://www.domain.example.com/cgi-bin/script.pl</code> would

be satisfied by executing the program

<code>/usr/local/apache/vhosts/10/20/30/40/cgi-bin/script.pl</code>.</p>

<p>If you want to include the <code>.</code> character in a

<code>VirtualDocumentRoot</code> directive, but it clashes with

a <code>%</code> directive, you can work around the problem in

the following way:</p>

<example>

VirtualDocumentRoot /usr/local/apache/vhosts/%2.0.%3.0

</example>

<p>A request for

<code>http://www.domain.example.com/directory/file.html</code>

will be satisfied by the file

<code>/usr/local/apache/vhosts/domain.example/directory/file.html</code>.</p>

<p>The <directive module="mod_log_config">LogFormat</directive>

directives <code>%V</code> and <code>%A</code> are useful

in conjunction with this module.</p>

</section>

<directivesynopsis>

<name>VirtualDocumentRoot</name>

<description>Dynamically configure the location of the document root

for a given virtual host</description>

<syntax>VirtualDocumentRoot <em>interpolated-directory</em>|none</syntax>

<default>VirtualDocumentRoot none</default>

<contextlist>

<context>server config</context>

<context>virtual host</context>

</contextlist>

<usage>

<p>The <directive>VirtualDocumentRoot</directive> directive allows you to

determine where Apache HTTP Server will find your documents based on the

value of the server name. The result of expanding

<em>interpolated-directory</em> is used as the root of the

document tree in a similar manner to the <directive

module="core">DocumentRoot</directive> directive's argument.

If <em>interpolated-directory</em> is <code>none</code> then

<directive>VirtualDocumentRoot</directive> is turned off. This directive

cannot be used in the same context as <directive

module="mod_vhost_alias">VirtualDocumentRootIP</directive>.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>VirtualDocumentRootIP</name>

<description>Dynamically configure the location of the document root

for a given virtual host</description>

<syntax>VirtualDocumentRootIP <em>interpolated-directory</em>|none</syntax>

<default>VirtualDocumentRootIP none</default>

<contextlist>

<context>server config</context>

<context>virtual host</context>

</contextlist>

<usage>

<p>The <directive>VirtualDocumentRootIP</directive> directive is like the

<directive module="mod_vhost_alias">VirtualDocumentRoot</directive>

directive, except that it uses the IP address of the server end

of the connection for directory interpolation instead of the server

name.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>VirtualScriptAlias</name>

<description>Dynamically configure the location of the CGI directory for

a given virtual host</description>

<syntax>VirtualScriptAlias <em>interpolated-directory</em>|none</syntax>

<default>VirtualScriptAlias none</default>

<contextlist>

<context>server config</context>

<context>virtual host</context>

</contextlist>

<usage>

<p>The <directive>VirtualScriptAlias</directive> directive allows you to

determine where Apache httpd will find CGI scripts in a similar

manner to <directive module="mod_vhost_alias"

>VirtualDocumentRoot</directive> does for other documents. It matches

requests for URIs starting <code>/cgi-bin/</code>, much like <directive

module="mod_alias">ScriptAlias</directive>

<code>/cgi-bin/</code> would.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>VirtualScriptAliasIP</name>

<description>Dynamically configure the location of the cgi directory for

a given virtual host</description>

<syntax>VirtualScriptAliasIP <em>interpolated-directory</em>|none</syntax>

<default>VirtualScriptAliasIP none</default>

<contextlist>

<context>server config</context>

<context>virtual host</context>

</contextlist>

<usage>

<p>The <directive>VirtualScriptAliasIP</directive> directive is like the

<directive module="mod_vhost_alias">VirtualScriptAlias</directive>

directive, except that it uses the IP address of the server end

of the connection for directory interpolation instead of the server

name.</p>

</usage>

</directivesynopsis>

</modulesynopsis>