= Installing Trac as CGI =

{{{
#!div class=important
  ''Please note that using Trac via CGI is the slowest deployment method available. It is slower than [TracModPython mod_python], [TracFastCgi FastCGI] and even [trac:TracOnWindowsIisAjp IIS/AJP] on Windows.''
}}}

CGI script is the entrypoint that web-server calls when a web-request to an application is made. To generate the `trac.cgi` script run:
{{{
trac-admin /path/to/env deploy /path/to/www/trac
}}}
`trac.cgi` will be in the `cgi-bin` folder inside the given path. Make sure it is executable by your web server. This command also copies `static resource` files to a `htdocs` directory of a given destination.

== Apache web-server configuration ==

In [http://httpd.apache.org/ Apache] there are two ways to run Trac as CGI:

 1. Use a `ScriptAlias` directive that maps an URL to the `trac.cgi` script (recommended)
 2. Copy the `trac.cgi` file into the directory for CGI executables used by your web server (commonly named `cgi-bin`). You can also create a symbolic link, but in that case make sure that the `FollowSymLinks` option is enabled for the `cgi-bin` directory.

To make Trac available at `http://yourhost.example.org/trac` add `ScriptAlias` directive to Apache configuration file, changing `trac.cgi` path to match your installation:
{{{
ScriptAlias /trac /path/to/www/trac/cgi-bin/trac.cgi
}}}

 ''Note that this directive requires enabled `mod_alias` module.''

If you're using Trac with a single project you need to set its location using the `TRAC_ENV` environment variable:
{{{
<Location "/trac">
  SetEnv TRAC_ENV "/path/to/projectenv"
</Location>
}}}

Or to use multiple projects you can specify their common parent directory using the `TRAC_ENV_PARENT_DIR` variable:
{{{
<Location "/trac">
  SetEnv TRAC_ENV_PARENT_DIR "/path/to/project/parent/dir"
</Location>
}}}

 ''Note that the `SetEnv` directive requires enabled `mod_env` module. It is also possible to set TRAC_ENV in trac.cgi. Just add the following code between "try:" and "from trac.web ...":''

{{{
    import os
    os.environ['TRAC_ENV'] = "/path/to/projectenv"
}}}

 '' Or for TRAC_ENV_PARENT_DIR: ''

{{{
    import os
    os.environ['TRAC_ENV_PARENT_DIR'] = "/path/to/project/parent/dir"
}}}

If you are using the [http://httpd.apache.org/docs/suexec.html Apache suEXEC] feature please see [http://trac.edgewall.org/wiki/ApacheSuexec].

On some systems, you ''may'' need to edit the shebang line in the `trac.cgi` file to point to your real Python installation path. On a Windows system you may need to configure Windows to know how to execute a .cgi file (Explorer -> Tools -> Folder Options -> File Types -> CGI).

== Mapping Static Resources ==

Out of the box, Trac will pass static resources such as style sheets or images through itself. For a CGI setup this is '''highly undesirable''', because this way CGI script is invoked for documents that could be much more efficiently served directly by web server.

Web servers such as [http://httpd.apache.org/ Apache] allow you to create “Aliases” to resources, giving them a virtual URL that doesn't necessarily reflect the layout of the servers file system. We already used this capability by defining a `ScriptAlias` for the CGI script. We also can map requests for static resources directly to the directory on the file system, avoiding processing these requests by CGI script.

There are two primary URL paths for static resources - `/chrome/common` and `/chrome/site`. Plugins can add their own resources usually accessible by `/chrome/plugin` path, so its important to override only known paths and not try to make universal `/chrome` alias for everything.

Add the following snippet to Apache configuration '''before''' the `ScriptAlias` for the CGI script, changing paths to match your deployment:
{{{
Alias /trac/chrome/common /path/to/trac/htdocs/common
Alias /trac/chrome/site /path/to/trac/htdocs/site
<Directory "/path/to/www/trac/htdocs">
  Order allow,deny
  Allow from all
</Directory>
}}}

If using mod_python, you might want to add this too (otherwise, the alias will be ignored):
{{{
<Location "/trac/chrome/common/">
  SetHandler None
</Location>
}}}

Note that we mapped `/trac` part of the URL to the `trac.cgi` script, and the path `/chrome/common` is the path you have to append to that location to intercept requests to the static resources. 

For example, if Trac is mapped to `/cgi-bin/trac.cgi` on your server, the URL of the Alias should be `/cgi-bin/trac.cgi/chrome/common`.

Similarly, if you have static resources in a project's htdocs directory (which is referenced by /chrome/site URL in themes), you can configure Apache to serve those resources (again, put this '''before''' the `ScriptAlias` for the CGI script, and adjust names and locations to match your installation):

{{{
Alias /trac/chrome/site /path/to/projectenv/htdocs
<Directory "/path/to/projectenv/htdocs">
  Order allow,deny
  Allow from all
</Directory>
}}}

Alternatively to hacking `/trac/chrome/site`, you can directly specify path to static resources using `htdocs_location` configuration option in [wiki:TracIni trac.ini]:
{{{
[trac]
htdocs_location = http://yourhost.example.org/trac-htdocs
}}}

Trac will then use this URL when embedding static resources into HTML pages. Of course, you still need to make the Trac `htdocs` directory available through the web server at the specified URL, for example by copying (or linking) the directory into the document root of the web server:
{{{
$ ln -s /path/to/www/trac/htdocs /var/www/yourhost.example.org/trac-htdocs
}}}

Note that in order to get this `htdocs` directory, you need first to extract the relevant Trac resources using the `deploy` command of TracAdmin:
[[TracAdminHelp(deploy)]]


== Adding Authentication ==

The simplest way to enable authentication with Apache is to create a password file. Use the `htpasswd` program to create the password file:
{{{
$ htpasswd -c /somewhere/trac.htpasswd admin
New password: <type password>
Re-type new password: <type password again>
Adding password for user admin
}}}

After the first user, you dont need the "-c" option anymore:
{{{
$ htpasswd /somewhere/trac.htpasswd john
New password: <type password>
Re-type new password: <type password again>
Adding password for user john
}}}

  ''See the man page for `htpasswd` for full documentation.''

After you've created the users, you can set their permissions using TracPermissions.

Now, you'll need to enable authentication against the password file in the Apache configuration:
{{{
<Location "/trac/login">
  AuthType Basic
  AuthName "Trac"
  AuthUserFile /somewhere/trac.htpasswd
  Require valid-user
</Location>
}}}

If you're hosting multiple projects you can use the same password file for all of them:
{{{
<LocationMatch "/trac/[^/]+/login">
  AuthType Basic
  AuthName "Trac"
  AuthUserFile /somewhere/trac.htpasswd
  Require valid-user
</LocationMatch>
}}}

For better security, it is recommended that you either enable SSL or at least use the “digest” authentication scheme instead of “Basic”. Please read the [http://httpd.apache.org/docs/2.0/ Apache HTTPD documentation] to find out more. For example, on a Debian 4.0r1 (etch) system the relevant section  in apache configuration can look like this:
{{{
<Location "/trac/login">
    LoadModule auth_digest_module /usr/lib/apache2/modules/mod_auth_digest.so
    AuthType Digest
    AuthName "trac"
    AuthDigestDomain /trac
    AuthUserFile /somewhere/trac.htpasswd
    Require valid-user
</Location>
}}}
and you'll have to create your .htpasswd file with htdigest instead of htpasswd as follows:
{{{
# htdigest /somewhere/trac.htpasswd trac admin
}}}
where the "trac" parameter above is the same as !AuthName above  ("Realm" in apache-docs). 

----
See also:  TracGuide, TracInstall, [wiki:TracModWSGI], TracFastCgi, TracModPython