Trac and mod_python

Trac 0.7.1 and later (not yet released) supports ​mod_python, which speeds up Trac's response times considerably and permits use of many Apache features not possible with tracd/mod_proxy.

Simple configuration

Here's a typical Trac CGI/Apache setup:

ScriptAlias /trac/myproject /path/to/python/share/trac/cgi-bin/trac.cgi
<Location /trac/myproject>
   SetEnv TRAC_ENV /var/svn/trac/myproject
</Location>

The equivalent mod_python setup is:

<Location /trac/myproject>
   SetHandler mod_python
   PythonHandler trac.ModPythonHandler
   PythonOption TracEnv /var/svn/trac/myproject
</Location>

Note: you might need to create a real physical trac/ directory (name matches the first location path segment from the above example) inside your DocumentRoot so that Trac can figure out the correct base location. That seems to be a problem (or feature?) with mod_python.

Setting up multiple projects

The hard way

The Trac mod_python handler can be configured to serve multiple projects, as can be seen in the following simple example:

<LocationMatch /trac/[[:alnum:]]+>
  SetHandler mod_python
  PythonHandler trac.ModPythonHandler
</LocationMatch>
<Location /trac/exampleone>
  PythonOption TracEnv "/var/www/projects/exampleone"
</Location>
<Location /trac/exampletwo>
  PythonOption TracEnv "/var/www/projects/exampletwo"
</Location>

This sets up two projects. The disadvantage of the approach used here is that you need one additional <Location> directive per Trac instance. Although you may be able to eliminate this using some mod_rewrite tricks, you can also make use of the built-in support for multiple projects, as described in the next section.

Or the easy way

The Trac mod_python handler handler supports a configuration option similar to Subversion's SvnParentPath, called TracEnvParentDir:

<LocationMatch /trac>
  SetHandler mod_python
  PythonHandler trac.ModPythonHandler
  PythonOption TracEnvParentDir "/var/www/projects"
</LocationMatch>

When you request the /trac URL, you will get a (currently very simple) listing of all subdirectories of the directory you set as TracEnvParentDir. Selecting any project in the list will bring you to the corresponding Trac instance. You should make sure that the configured directory only contains Trac environment directories that match the currently installed Trac version, because that is not checked prior the the generation of the project list.

A word of warning

Don't be tempted into using the ​support for multiple python interpreters! There appears to be a problem with loading the ClearSilver library (and/or python bindings) more than once per process. When you try to use multiple interpreters, every instance other than the first instance you accessed will fail with an import error on neo_cs.

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See also TracGuide, TracInstall, TracMultipleProjects