Trac and mod_python
Trac 0.7.1 and later supports mod_python, which speeds up Trac's response times considerably and permits use of many Apache features not possible with tracd/mod_proxy.
Here's a typical Trac CGI/Apache setup:
ScriptAlias /projects/myproject /path/to/python/share/trac/cgi-bin/trac.cgi
SetEnv TRAC_ENV /var/trac/myproject
The equivalent mod_python setup is:
PythonOption TracUriRoot "/projects/myproject"
PythonOption TracEnv /var/trac/myproject
Note that the option TracUriRoot may or may not be necessary in your setup. Try without first, and if the URLs produced by Trac look wrong, add the TracUriRoot option.
Setting up multiple projects
The Trac mod_python handler handler supports a configuration option similar to Subversion's SvnParentPath, called TracEnvParentDir:
PythonOption TracUriRoot /projects
PythonOption TracEnvParentDir "/var/trac"
When you request the /projects 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.
Adding authentication is straightforward in both cases. For example:
If you run trac with mod_python on Windows, attachments will not work.
There is a (simple) workaround for this which is to apply the patch attached to
See also TracGuide, TracInstall, TracMultipleProjects