Пункт 38. Dynamic virtual hosts with mod_rewrite
This document supplements the mod_rewrite
reference documentation. It describes
how you can use mod_rewrite to create dynamically
configured virtual hosts.
mod_rewrite is not the best way to configure
virtual hosts. You should first consider the alternatives before resorting to
mod_rewrite. See also the "how to avoid
mod_rewrite document.
Virtual Hosts For Arbitrary Hostnames
- Description:
-
We want to automatically create a virtual host for every hostname
which resolves in our domain, without having to create
new VirtualHost sections.
In this recipe, we assume that we'll be using the hostname
www.SITE.example.com for each
user, and serve their content out of
/home/SITE/www .
- Solution:
-
RewriteEngine on
RewriteMap lowercase int:tolower
RewriteCond "${lowercase:%{HTTP_HOST}}" "^www\.([^.]+)\.example\.com$"
RewriteRule "^(.*)" "/home/%1/www$1"
- Discussion
-
You will need to take care of the DNS
resolution - Apache does
not handle name resolution. You'll need either to create CNAME
records for each hostname, or a DNS wildcard record. Creating DNS
records is beyond the scope of this document.
The internal tolower RewriteMap directive is used to
ensure that the hostnames being used are all lowercase, so that there is
no ambiguity in the directory structure which must be created.
Parentheses used in a RewriteCond are captured into the
backreferences %1 , %2 , etc, while parentheses
used in RewriteRule are
captured into the backreferences $1 , $2 ,
etc.
As with many techniques discussed in this document, mod_rewrite really
isn't the best way to accomplish this task. You should, instead,
consider using mod_vhost_alias instead, as it will much
more gracefully handle anything beyond serving static files, such as any
dynamic content, and Alias resolution.
Dynamic
Virtual Hosts Using mod_rewrite
This extract from apache2.conf does the same
thing as the first example. The first
half is very similar to the corresponding part above, except for
some changes, required for backward compatibility and to make the
mod_rewrite part work properly; the second half
configures mod_rewrite to do the actual work.
Because mod_rewrite runs before other URI translation
modules (e.g., mod_alias ), mod_rewrite must
be told to explicitly ignore any URLs that would have been handled
by those modules. And, because these rules would otherwise bypass
any ScriptAlias directives, we must have
mod_rewrite explicitly enact those mappings.
# get the server name from the Host: header
UseCanonicalName Off
# splittable logs
LogFormat "%{Host}i %h %l %u %t \"%r\" %s %b" vcommon
CustomLog "logs/access_log" vcommon
<Directory "/www/hosts">
# ExecCGI is needed here because we can't force
# CGI execution in the way that ScriptAlias does
Options FollowSymLinks ExecCGI
</Directory>
RewriteEngine On
# a ServerName derived from a Host: header may be any case at all
RewriteMap lowercase int:tolower
## deal with normal documents first:
# allow Alias "/icons/" to work - repeat for other aliases
RewriteCond "%{REQUEST_URI}" "!^/icons/"
# allow CGIs to work
RewriteCond "%{REQUEST_URI}" "!^/cgi-bin/"
# do the magic
RewriteRule "^/(.*)$" "/www/hosts/${lowercase:%{SERVER_NAME}}/docs/$1"
## and now deal with CGIs - we have to force a handler
RewriteCond "%{REQUEST_URI}" "^/cgi-bin/"
RewriteRule "^/(.*)$" "/www/hosts/${lowercase:%{SERVER_NAME}}/cgi-bin/$1" [H=cgi-script]
Using a Separate Virtual Host Configuration File
This arrangement uses more advanced mod_rewrite
features to work out the translation from virtual host to document
root, from a separate configuration file. This provides more
flexibility, but requires more complicated configuration.
The vhost.map file should look something like
this:
customer-1.example.com /www/customers/1
customer-2.example.com /www/customers/2
# ...
customer-N.example.com /www/customers/N
The apache2.conf should contain the following:
RewriteEngine on
RewriteMap lowercase int:tolower
# define the map file
RewriteMap vhost "txt:/www/conf/vhost.map"
# deal with aliases as above
RewriteCond "%{REQUEST_URI}" "!^/icons/"
RewriteCond "%{REQUEST_URI}" "!^/cgi-bin/"
RewriteCond "${lowercase:%{SERVER_NAME}}" "^(.+)$"
# this does the file-based remap
RewriteCond "${vhost:%1}" "^(/.*)$"
RewriteRule "^/(.*)$" "%1/docs/$1"
RewriteCond "%{REQUEST_URI}" "^/cgi-bin/"
RewriteCond "${lowercase:%{SERVER_NAME}}" "^(.+)$"
RewriteCond "${vhost:%1}" "^(/.*)$"
RewriteRule "^/cgi-bin/(.*)$" "%1/cgi-bin/$1" [H=cgi-script]
