Dynamic mass virtual hosts with mod_rewrite

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+ + +

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
Dynamic + Virtual Hosts Using mod_rewrite
Using a Separate Virtual Host Configuration File

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 httpd.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 httpd.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]

+ + +

Dynamic mass virtual hosts with mod_rewrite

See also

Virtual Hosts For Arbitrary Hostnames

Dynamic + Virtual Hosts Using mod_rewrite

Using a Separate Virtual Host Configuration File

Comments

Dynamic + Virtual Hosts Using `mod_rewrite`