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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>

<highlight language="config">

ScriptAlias "/cgi-bin/" "/usr/local/apache2/cgi-bin/"

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

</highlight>

</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>

<highlight language="config">

UseCanonicalName Off

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

</highlight>

<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>

<highlight language="config">

UseCanonicalName Off

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

</highlight>

<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>

<highlight language="config">

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

</highlight>

<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>

<highlight language="config">

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

</highlight>

<p>The example request would come from

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

<p> A very common request by users is the ability to point multiple domains to multiple

document roots without having to worry about the length or number of parts of the

hostname being requested. If the requested hostname is <code>sub.www.domain.example.com</code>

instead of simply <code>www.domain.example.com</code>, then using %3+ will result in the document

root being <code>/usr/local/apache/vhosts/domain.example.com/...</code> instead of the

intended <code>example.com</code> directory. In such cases, it can be beneficial to use

the combination <code>%-2.0.%-1.0</code>, which will always yield the domain name and the

tld, for example <code>example.com</code> regardless of the number of subdomains appended

to the hostname. As such, one can make a configuration that will direct all first, second

or third level subdomains to the same directory:

</p>

<highlight language="config">

VirtualDocumentRoot "/usr/local/apache/vhosts/%-2.0.%-1.0"

</highlight>

<p>

In the example above, both <code>www.example.com</code> as well as <code>www.sub.example.com</code>

or <code>example.com</code> will all point to <code>/usr/local/apache/vhosts/example.com</code>.

</p>

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

your configuration file:</p>

<highlight language="config">

UseCanonicalName DNS

VirtualDocumentRootIP "/usr/local/apache/vhosts/%1/%2/%3/%4/docs"

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

</highlight>

<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>

<highlight language="config">

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

</highlight>

<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>

<note type="warning"><title>Note</title>

<directive>VirtualDocumentRoot</directive> will override any <directive

module="core">DocumentRoot</directive> directives you may have put in the same

context or child contexts. Putting a <directive>VirtualDocumentRoot</directive>

in the global server scope will effectively override <directive

module="core">DocumentRoot</directive> directives in any virtual hosts defined later

on, unless you set <directive>VirtualDocumentRoot</directive> to <code>None</code>

in each virtual host.

</note>

</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>