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= Trac Plugins =
[[TracGuideToc]]

Since version 0.9, Trac supports plugins that extend the built-in functionality. The plugin functionality is based on the [http://projects.edgewall.com/trac/wiki/TracDev/ComponentArchitecture component architecture].

== Requirements ==

To use plugins in Trac, you need to have [http://peak.telecommunity.com/DevCenter/setuptools setuptools] (version 0.6) installed.

To install `setuptools`, download the bootstrap module [http://peak.telecommunity.com/dist/ez_setup.py ez_setup.py] and execute it as follows:
{{{
$ python ez_setup.py
}}}

If the `ez_setup.py` script fails to install the setuptools release, you can download it from [http://www.python.org/pypi/setuptools PyPI] and install it manually.

== Installing a Trac Plugin ==

=== For a Single Project ===

Plugins are packaged as [http://peak.telecommunity.com/DevCenter/PythonEggs Python eggs]. That means they are ZIP archives with the file extension `.egg`. If you have downloaded a source distribution of a plugin, you can run:
{{{
$ python setup.py bdist_egg
}}}
to build the `.egg` file.

Once you have the plugin archive, you need to copy it into the `plugins` directory of the [wiki:TracEnvironment project environment]. Also, make sure that the web server has sufficient permissions to read the plugin egg.

=== For All Projects ===

Plugins that you want to use in all your projects (such as [http://projects.edgewall.com/trac/wiki/WebAdmin WebAdmin]) can be installed globally by running:
{{{
$ python setup.py install
}}}

Alternatively, you can just drop the `.egg` file in the Python `site-packages` directory.

Unlike plugins installed per-environment, you'll have to explicitly enable globally installed plugins via [wiki:TracIni trac.ini]. This is done in the `[components]` section of the configuration file, for example:
{{{
[components]
webadmin.* = enabled
}}}

The name of the option is the Python package of the plugin. This should be specified in the documentation of the Plugin, but can also be easily find out by looking at the source (look for a top-level directory that contains a file named `__init__.py`.)

== Setting up the Plugin Cache ==

Some plugins will need to be extracted by the Python eggs runtime (`pkg_resources`), so that their contents are actual files on the file system. The directory in which they are extracted defaults to the home directory of the current user, which may or may not be a problem. You can however override the default location using the `PYTHON_EGG_CACHE` environment variable.

To do this from the Apache configuration, use the `SetEnv` directive as follows:
{{{
SetEnv PYTHON_EGG_CACHE /path/to/dir
}}}

This works whether your using the [wiki:TracCgi CGI] or the [wiki:TracModPython mod_python] front-end. Put this directive next to where you set the path to the [wiki:TracEnvironment Trac environment], i.e. in the same `<Location>` block.

For example (for CGI):
{{{
 <Location /trac>
   SetEnv TRAC_ENV /path/to/projenv
   SetEnv PYTHON_EGG_CACHE /path/to/dir
 </Location>
}}}

or (for mod_python):
{{{
 <Location /trac>
   SetHandler mod_python
   ...
   SetEnv PYTHON_EGG_CACHE /path/to/dir
 </Location>
}}}

For [wiki:TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.

----
See also TracGuide, [http://projects.edgewall.com/trac/wiki/PluginList plugin list], [http://projects.edgewall.com/trac/wiki/TracDev/ComponentArchitecture component architecture]