Apache Module mod_vhost_alias
Summary
This module creates dynamically configured virtual hosts, by
allowing the IP address and/or the Host: 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.
Note
If mod_alias or mod_userdir are
used for translating URIs to filenames, they will override the
directives of mod_vhost_alias described below. For
example, the following configuration will map
/cgi-bin/script.pl to
/usr/local/apache2/cgi-bin/script.pl in all cases:
ScriptAlias /cgi-bin/ /usr/local/apache2/cgi-bin/
VirtualScriptAlias /never/found/%0/cgi-bin/
Directives
Topics
See also
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 UseCanonicalName
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 printf which have a number of formats:
%% |
insert a % |
%p |
insert the port number of the virtual host |
%N.M |
insert (part of) the name |
N and M are used to specify
substrings of the name. N selects from the
dot-separated components of the name, and M
selects characters within whatever N has selected.
M is optional and defaults to zero if it isn't
present; the dot must be present if and only if M
is present. The interpretation is as follows:
0 |
the whole name |
1 |
the first part |
2 |
the second part |
-1 |
the last part |
-2 |
the penultimate part |
2+ |
the second and all subsequent parts |
-2+ |
the penultimate and all preceding parts |
1+ and -1+ |
the same as 0 |
If N or M is greater than the number
of parts available a single underscore is interpolated.
For simple name-based virtual hosts you might use the
following directives in your server configuration file:
UseCanonicalName Off
VirtualDocumentRoot /usr/local/apache/vhosts/%0
A request for
http://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 the
vhosts directory. To do this you might use the
following in your configuration file:
UseCanonicalName Off
VirtualDocumentRoot /usr/local/apache/vhosts/%3+/%2.1/%2.2/%2.3/%2
A request for
http://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.
For IP-based virtual hosting you might use the following in
your configuration file:
UseCanonicalName DNS
VirtualDocumentRootIP /usr/local/apache/vhosts/%1/%2/%3/%4/docs
VirtualScriptAliasIP /usr/local/apache/vhosts/%1/%2/%3/%4/cgi-bin
A request for
http://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 of www.domain.example.com were
10.20.30.40. A request for
http://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 a
VirtualDocumentRoot 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 for
http://www.domain.example.com/directory/file.html
will be satisfied by the file
/usr/local/apache/vhosts/domain.example/directory/file.html.
The LogFormat
directives %V and %A are useful
in conjunction with this module.
| Description: | Dynamically configure the location of the document root
for a given virtual host |
|---|
| Syntax: | VirtualDocumentRoot interpolated-directory|none |
|---|
| Default: | VirtualDocumentRoot none |
|---|
| Context: | server config, virtual host |
|---|
| Status: | Extension |
|---|
| Module: | mod_vhost_alias |
|---|
The VirtualDocumentRoot directive allows you to
determine where Apache will find your documents based on the
value of the server name. The result of expanding
interpolated-directory is used as the root of the
document tree in a similar manner to the DocumentRoot directive's argument.
If interpolated-directory is none then
VirtualDocumentRoot is turned off. This directive
cannot be used in the same context as VirtualDocumentRootIP.
| Description: | Dynamically configure the location of the document root
for a given virtual host |
|---|
| Syntax: | VirtualDocumentRootIP interpolated-directory|none |
|---|
| Default: | VirtualDocumentRootIP none |
|---|
| Context: | server config, virtual host |
|---|
| Status: | Extension |
|---|
| Module: | mod_vhost_alias |
|---|
The VirtualDocumentRootIP directive is like the
VirtualDocumentRoot
directive, except that it uses the IP address of the server end
of the connection for directory interpolation instead of the server
name.
| Description: | Dynamically configure the location of the CGI directory for
a given virtual host |
|---|
| Syntax: | VirtualScriptAlias interpolated-directory|none |
|---|
| Default: | VirtualScriptAlias none |
|---|
| Context: | server config, virtual host |
|---|
| Status: | Extension |
|---|
| Module: | mod_vhost_alias |
|---|
The VirtualScriptAlias directive allows you to
determine where Apache will find CGI scripts in a similar
manner to VirtualDocumentRoot does for other documents. It matches
requests for URIs starting /cgi-bin/, much like ScriptAlias
/cgi-bin/ would.
| Description: | Dynamically configure the location of the cgi directory for
a given virtual host |
|---|
| Syntax: | VirtualScriptAliasIP interpolated-directory|none |
|---|
| Default: | VirtualScriptAliasIP none |
|---|
| Context: | server config, virtual host |
|---|
| Status: | Extension |
|---|
| Module: | mod_vhost_alias |
|---|
The VirtualScriptAliasIP directive is like the
VirtualScriptAlias
directive, except that it uses the IP address of the server end
of the connection for directory interpolation instead of the server
name.
