Apache Module mod_vhost_alias

Summary

This module creates dynamically configured virtual hosts, by allowing the IP address and/or theHost: 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.

ScriptAlias "/cgi-bin/" "/usr/local/apache2/cgi-bin/"VirtualScriptAlias "/never/found/%0/cgi-bin/"

Topics

• Directory Name Interpolation
• Examples

Directives

• VirtualDocumentRoot
• VirtualDocumentRootIP
• VirtualScriptAlias
• VirtualScriptAliasIP

Bugfix checklist

• httpd changelog
• Known issues
• Report a bug

See also

• UseCanonicalName
• Dynamically configured mass virtual hosting
• Comments

Directory Name Interpolation

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 theUseCanonicalName 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 byprintf which have a number of formats:

N andM are used to specify substrings of the name.N selects from the dot-separated components of the name, andM selects characters within whateverN has selected.M is optional and defaults to zero if it isn't present; the dot must be present if and only ifM is present. The interpretation is as follows:

IfN orM is greater than the number of parts available a single underscore is interpolated.

Examples

For simple name-based virtual hosts you might use the following directives in your server configuration file:

UseCanonicalName    OffVirtualDocumentRoot "/usr/local/apache/vhosts/%0"

A request forhttp://www.example.com/directory/file.html will be satisfied by the file/usr/local/apache/vhosts/www.example.com/directory/file.html.

For a very large number of virtual hosts it is a good idea to arrange the files to reduce the size of thevhosts directory. To do this you might use the following in your configuration file:

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

A request forhttp://www.domain.example.com/directory/file.html will be satisfied by the file/usr/local/apache/vhosts/example.com/d/o/m/domain/directory/file.html.

A more even spread of files can be achieved by hashing from the end of the name, for example:

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

The example request would come from/usr/local/apache/vhosts/example.com/n/i/a/domain/directory/file.html.

Alternatively you might use:

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

The example request would come from/usr/local/apache/vhosts/example.com/d/o/m/ain/directory/file.html.

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 issub.www.domain.example.com instead of simplywww.domain.example.com, then using %3+ will result in the documentroot being/usr/local/apache/vhosts/domain.example.com/... instead of theintendedexample.com directory. In such cases, it can be beneficial to use the combination%-2.0.%-1.0, which will always yield the domain name and the tld, for exampleexample.com 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:

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

In the example above, bothwww.example.com as well aswww.sub.example.comorexample.com will all point to/usr/local/apache/vhosts/example.com.

For IP-based virtual hosting you might use the following in your configuration file:

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

A request forhttp://www.domain.example.com/directory/file.html would be satisfied by the file/usr/local/apache/vhosts/10/20/30/40/docs/directory/file.html if the IP address ofwww.domain.example.com were 10.20.30.40. A request forhttp://www.domain.example.com/cgi-bin/script.pl would be satisfied by executing the program/usr/local/apache/vhosts/10/20/30/40/cgi-bin/script.pl.

If you want to include the. character in aVirtualDocumentRoot directive, but it clashes with a% directive, you can work around the problem in the following way:

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

A request forhttp://www.domain.example.com/directory/file.html will be satisfied by the file/usr/local/apache/vhosts/domain.example/directory/file.html.

TheLogFormat directives%V and%A are useful in conjunction with this module.

VirtualDocumentRootDirective

TheVirtualDocumentRoot directive allows you to determine where Apache HTTP Server will find your documents based on the value of the server name. The result of expandinginterpolated-directory is used as the root of the document tree in a similar manner to theDocumentRoot directive's argument. Ifinterpolated-directory isnone thenVirtualDocumentRoot is turned off. This directive cannot be used in the same context asVirtualDocumentRootIP.

VirtualDocumentRootIPDirective

TheVirtualDocumentRootIP directive is like theVirtualDocumentRoot directive, except that it uses the IP address of the server end of the connection for directory interpolation instead of the server name.

VirtualScriptAliasDirective

TheVirtualScriptAlias directive allows you to determine where Apache httpd will find CGI scripts in a similar manner toVirtualDocumentRoot does for other documents. It matches requests for URIs starting/cgi-bin/, much likeScriptAlias/cgi-bin/ would.

VirtualScriptAliasIPDirective

TheVirtualScriptAliasIP directive is like theVirtualScriptAlias directive, except that it uses the IP address of the server end of the connection for directory interpolation instead of the server name.