Recipe 4.7 Mass Virtual Hosting Using Rewrite Rules

Problem

Although there is a module—mod_vhost_alias—which is explicitly for the purpose of supporting large numbers of virtual hosts, it is very limiting and requires that every virtual host be configured exactly the same way. You want to support a large number of vhosts, configured dynamically, but, at the same time, you want to avoid mod_vhost_alias.

Solution

Use directives from mod_rewrite to map to a directory based on the hostname:

RewriteEngine on
RewriteCond   %{HTTP_HOST}     ^(www\.)?([^.]+)\.com$
RewriteRule   ^(.*)$   /home/%2$1

Discussion

mod_vhost_alias is useful, but it is best for settings where each virtual host is identical in every way but hostname. Using mod_vhost_alias precludes the use of other URL-mapping modules, such as mod_userdir, mod_rewrite, and mod_alias, and it can be very restrictive. Using mod_rewrite is less efficient, but it is more flexible.

For example, when using mod_vhost_alias, you must do all of your hosts with mod_vhost_alias; whereas with this alternate approach, you can do some of your hosts using the rewrite rules and others using conventional virtual host configuration techniques.

The directives in the Solution map requests for www.something.com (or without the www) to the directory /home/something.

See Also

• Recipe 5.16

• http://httpd.apache.org/docs/vhosts/

• http://httpd.apache.org/docs/vhosts/

• http://httpd.apache.org/docs/mod/mod_rewrite.html