Changes from Version 1 of TracPlugins

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trac (IP: 127.0.0.1)
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09/25/08 15:44:25 (9 years ago)
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  • TracPlugins

    v0 v1  
     1= Trac Plugins = 
     2[[TracGuideToc]] 
     3 
     4Since version 0.9, Trac supports plugins that extend the built-in functionality. The plugin functionality is based on the [http://trac.edgewall.org/wiki/TracDev/ComponentArchitecture component architecture]. 
     5 
     6== Requirements == 
     7 
     8To use egg based plugins in Trac, you need to have [http://peak.telecommunity.com/DevCenter/setuptools setuptools] (version 0.6) installed. 
     9 
     10Plugins can also consist of a single `.py` file dropped into either the environment or global `plugins` directory ''(since [milestone:0.10])''. 
     11 
     12To install `setuptools`, download the bootstrap module [http://peak.telecommunity.com/dist/ez_setup.py ez_setup.py] and execute it as follows: 
     13{{{ 
     14$ python ez_setup.py 
     15}}} 
     16 
     17If 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. 
     18 
     19== Installing a Trac Plugin == 
     20 
     21=== For a Single Project === 
     22 
     23Plugins 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: 
     24{{{ 
     25$ python setup.py bdist_egg 
     26}}} 
     27to build the `.egg` file. 
     28 
     29Once 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. 
     30 
     31Note that the Python version that the egg is built with must 
     32match the Python version with which Trac is run.  If for 
     33instance you are running Trac under Python 2.3, but have 
     34upgraded your standalone Python to 2.4, the eggs won't be 
     35recognized. 
     36 
     37=== For All Projects === 
     38 
     39==== With an .egg file ==== 
     40 
     41Some plugins (such as [http://trac.edgewall.org/wiki/WebAdmin WebAdmin]) are downloadable as a `.egg` file which can be installed with the `easy_install` program: 
     42{{{ 
     43easy_install TracWebAdmin-0.1.1dev_r2765-py2.3.egg 
     44}}} 
     45 
     46If `easy_install` is not on your system see the Requirements section above to install it.  Windows users will need to add the `Scripts` directory of their Python installation (for example, `C:\Python23\Scripts`) to their `PATH` environment variable (see [http://peak.telecommunity.com/DevCenter/EasyInstall#windows-notes easy_install Windows notes] for more information). 
     47 
     48If Trac reports permission errors after installing a zipped egg and you would rather not bother providing a egg cache directory writable by the web server, you can get around it by simply unzipping the egg. Just pass `--always-unzip` to `easy_install`: 
     49{{{ 
     50easy_install --always-unzip TracWebAdmin-0.1.1dev_r2765-py2.3.egg 
     51}}} 
     52You should end up with a directory having the same name as the zipped egg (complete with `.egg` extension) and containing its uncompressed contents. 
     53 
     54Trac also searches for globally installed plugins under `$prefix/share/trac/plugins` ''(since 0.10)''. 
     55 
     56==== From source ==== 
     57 
     58If you downloaded the plugin's source from Subversion, or a source zip file you can install it using the included `setup.py`: 
     59{{{ 
     60$ python setup.py install 
     61}}} 
     62 
     63==== Enabling the plugin ==== 
     64Unlike 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: 
     65{{{ 
     66[components] 
     67webadmin.* = enabled 
     68}}} 
     69 
     70The 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`.) 
     71 
     72Note: After installing the plugin, you may need to restart Apache. 
     73 
     74== Setting up the Plugin Cache == 
     75 
     76Some 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. 
     77 
     78To do this from the Apache configuration, use the `SetEnv` directive as follows: 
     79{{{ 
     80SetEnv PYTHON_EGG_CACHE /path/to/dir 
     81}}} 
     82 
     83This works whether you are 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. 
     84 
     85For example (for CGI): 
     86{{{ 
     87 <Location /trac> 
     88   SetEnv TRAC_ENV /path/to/projenv 
     89   SetEnv PYTHON_EGG_CACHE /path/to/dir 
     90 </Location> 
     91}}} 
     92 
     93or (for mod_python): 
     94{{{ 
     95 <Location /trac> 
     96   SetHandler mod_python 
     97   ... 
     98   SetEnv PYTHON_EGG_CACHE /path/to/dir 
     99 </Location> 
     100}}} 
     101 
     102 ''Note: this requires the `mod_env` module'' 
     103 
     104For [wiki:TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables. 
     105 
     106=== About hook scripts === 
     107 
     108If you have set up some subversion hook scripts that call the Trac engine - such as the post-commit hook script provided in the `/contrib` directory - make sure you define the `PYTHON_EGG_CACHE` environment variable within these scripts as well. 
     109 
     110== Troubleshooting == 
     111 
     112=== Is setuptools properly installed? === 
     113 
     114Try this from the command line: 
     115{{{ 
     116$ python -c "import pkg_resources" 
     117}}} 
     118 
     119If you get '''no output''', setuptools '''is''' installed. Otherwise, you'll need to install it before plugins will work in Trac. 
     120 
     121=== Did you get the correct version of the Python egg? === 
     122 
     123Python eggs have the Python version encoded in their filename. For example, `MyPlugin-1.0-py2.4.egg` is an egg for Python 2.4, and will '''not''' be loaded if you're running a different Python version (such as 2.3 or 2.5). 
     124 
     125Also, verify that the egg file you downloaded is indeed a ZIP archive. If you downloaded it from a Trac site, chances are you downloaded the HTML preview page instead. 
     126 
     127=== Is the plugin enabled? === 
     128 
     129If you install a plugin globally (i.e. ''not'' inside the `plugins` directory of the Trac project environment) you will have to explicitly enable it in [TracIni trac.ini]. Make sure that: 
     130 * you actually added the necessary line(s) to the `[components]` section 
     131 * the package/module names are correct 
     132 * if you're reference a module (as opposed to a class), you've appended the necessary “.*” 
     133 * the value is “enabled", not e.g. “enable” 
     134 
     135=== Check the permissions on the egg file === 
     136 
     137Trac must of course be able to read the file. Yeah, you knew that ;-) 
     138 
     139=== Check the log files === 
     140 
     141Enable [TracLogging logging] in Trac, set the log level to `DEBUG` and then watch the log file for messages about loading plugins. 
     142 
     143---- 
     144See also TracGuide, [http://trac.edgewall.org/wiki/PluginList plugin list], [http://trac.edgewall.org/wiki/TracDev/ComponentArchitecture component architecture]