# Changes between Version 1 and Version 2 of TracPlugins

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Timestamp:
05/09/10 05:59:49 (12 years ago)
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 v1 [[TracGuideToc]] Since 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]. Since version 0.9, Trac supports [trac:PluginList plugins] that extend the built-in functionality. The plugin functionality is based on the [trac:TracDev/ComponentArchitecture component architecture]. Plugins can be installed globally (in this case they should be explicitly enabled in [TracIni#components-section trac.ini]) or locally for specific TracEnvironment. == Requirements == To use egg based plugins in Trac, you need to have [http://peak.telecommunity.com/DevCenter/setuptools setuptools] (version 0.6) installed. Plugins can also consist of a single .py file dropped into either the environment or global plugins directory ''(since [milestone:0.10])''. To install setuptools, download the bootstrap module [http://peak.telecommunity.com/dist/ez_setup.py ez_setup.py] and execute it as follows: 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. Plugins can also consist of a single .py file dropped into either the environment or global plugins directory ''(since [milestone:0.10])''. See TracIni#GlobalConfiguration . == 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: 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, and want to build the .egg file, follow this instruction: * Unpack the source. It should provide a setup.py. * 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. Then you will have a *.egg file. Examine the output of running python to find where this was created. 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. Then, restart the web server (this requirement was not previously mentioned in this document, but in my tests it began working only after I did so). To uninstall a plugin installed this way, remove the egg from plugins directory and restart web server. Note that the Python version that the egg is built with must recognized. Note also that in a multi-project setup, a pool of Python interpreter instances will be dynamically allocated to projects based on need, and since plugins occupy a place in Python's module system, the first version of any given plugin to be loaded will be used for all the projects. In other words, you cannot use different versions of a single plugin in two projects of a multi-project setup. It may be safer to install plugins for all projects (see below) and then enable them selectively on a project-by-project basis. === For All Projects === ==== With an .egg file ==== Some 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: Some plugins (such as [trac:SpamFilter SpamFilter]) are downloadable as a .egg file which can be installed with the easy_install program: {{{ easy_install TracWebAdmin-0.1.1dev_r2765-py2.3.egg easy_install TracSpamFilter }}} If 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: {{{ easy_install --always-unzip TracWebAdmin-0.1.1dev_r2765-py2.3.egg easy_install --always-unzip TracSpamFilter-0.2.1dev_r5943-py2.4.egg }}} You should end up with a directory having the same name as the zipped egg (complete with .egg extension) and containing its uncompressed contents. Trac also searches for globally installed plugins under $prefix/share/trac/plugins ''(since 0.10)''. Trac also searches for globally installed plugins ''(since 0.10)'', see TracIni#GlobalConfiguration. ==== From source ==== If you downloaded the plugin's source from Subversion, or a source zip file you can install it using the included setup.py: easy_install makes installing from source a snap. Just give it the URL to either a Subversion repository or a tarball/zip of the source: {{{ $python setup.py install easy_install http://svn.edgewall.com/repos/trac/plugins/0.11/spam-filter }}} ==== Enabling the plugin ==== 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: Unlike plugins installed per-environment, you'll have to explicitly enable globally installed plugins via [wiki:TracIni trac.ini]. This also applies to plugins installed in the path specified in the [inherit] plugins_dir configuration option. This is done in the [components] section of the configuration file, for example: {{{ [components] webadmin.* = enabled tracspamfilter.* = 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.) 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 discovered by looking at the source (look for a top-level directory that contains a file named __init__.py.) Note: After installing the plugin, you may need to restart Apache. Note: After installing the plugin, you need to restart your web server. ==== Uninstalling ==== easy_install or python setup.py does not have an uninstall feature. Hower, it is usually quite trivial to remove a globally installed egg and reference: 1. Do easy_install -m [plugin name] to remove references from $PYTHONLIB/site-packages/easy-install.pth when the plugin installed by setuptools. 1. Delete executables from /usr/bin, /usr/local/bin or C:\\Python*\Scripts. For search what executables are there, you may refer to [console-script] section of setup.py. 1. Delete the .egg file or folder from where it is installed, usually inside \$PYTHONLIB/site-packages/. 1. Restart web server. If you are uncertain about the location of the egg, here is a small tip to help locate an egg (or any package) - replace myplugin with whatever namespace the plugin uses (as used when enabling the plugin): {{{ >>> import myplugin >>> print myplugin.__file__ /opt/local/python24/lib/site-packages/myplugin-0.4.2-py2.4.egg/myplugin/__init__.pyc }}} == 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. 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 '.python-eggs' in 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: }}} ''Note: this requires the mod_env module'' ''Note: !SetEnv requires the mod_env module which needs to be activated for Apache. In this case the !SetEnv directive can also be used in the mod_python Location block.'' For [wiki:TracFastCgi FastCGI], you'll need to -initial-env option, or whatever is provided by your web server for setting environment variables. For [wiki:TracFastCgi FastCGI], you'll need to -initial-env option, or whatever is provided by your web server for setting environment variables. ''Note: that if you already use -initial-env to set the project directory for either a single project or parent you will need to add an additional -initial-env directive to the !FastCgiConfig directive. I.e. {{{ FastCgiConfig -initial-env TRAC_ENV=/var/lib/trac -initial-env PYTHON_EGG_CACHE=/var/lib/trac/plugin-cache }}} === About hook scripts === === Is the plugin enabled? === If 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: * you actually added the necessary line(s) to the [components] section * the package/module names are correct * if you're reference a module (as opposed to a class), you've appended the necessary “.*” * the value is “enabled", not e.g. “enable” === Check the permissions on the egg file === Trac must of course be able to read the file. Yeah, you knew that ;-) Trac must be able to read the file. === Check the log files === Enable [TracLogging logging] in Trac, set the log level to DEBUG and then watch the log file for messages about loading plugins. Enable [wiki:TracLogging logging] and set the log level to DEBUG, then watch the log file for messages about loading plugins. === Verify you have proper permissions === Some plugins require you have special permissions in order to use them. [trac:WebAdmin WebAdmin], for example, requires the user to have TRAC_ADMIN permissions for it to show up on the navigation bar. === Is the wrong version of the plugin loading? === If you put your plugins inside plugins directories, and certainly if you have more than one project, you need to make sure that the correct version of the plugin is loading. Here are some basic rules: * Only one version of the plugin can be loaded for each running Trac server (ie. each Python process). The Python namespaces and module list will be shared, and it cannot handle duplicates. Whether a plugin is enabled or disabled makes no difference. * A globally installed plugin (typically setup.py install) will override any version in global or project plugins directories. A plugin from the global plugins directory will be located before any project plugins directory. * If your Trac server hosts more than one project (as with TRAC_ENV_PARENT_DIR setups), then having two versions of a plugin in two different projects will give uncertain results. Only one of them will load, and the one loaded will be shared by both projects. Trac will load the first found - basically from the project that receives the first request. * Having more than one version listed inside Python site-packages is fine (ie. installed with setup.py install) - setuptools will make sure you get the version installed most recently. However, don't store more than one version inside a global or project plugins directory - neither version number nor installed date will matter at all. There is no way to determine which one will be located first when Trac searches the directory for plugins. === If all of the above failed === OK, so the logs don't mention plugins, the egg is readable, the python version is correct ''and'' the egg has been installed globally (and is enabled in the trac.ini) and it still doesn't work or give any error messages or any other indication as to why? Hop on the [trac:IrcChannel IrcChannel] and ask away. ---- See also TracGuide, [http://trac.edgewall.org/wiki/PluginList plugin list], [http://trac.edgewall.org/wiki/TracDev/ComponentArchitecture component architecture] See also TracGuide, [trac:PluginList plugin list], [trac:TracDev/ComponentArchitecture component architecture]