Changes between Version 1 and Version 2 of TracPlugins


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Timestamp:
Feb 22, 2011, 12:40:16 AM (9 years ago)
Author:
trac
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  • TracPlugins

    v1 v2  
    22[[TracGuideToc]]
    33
    4 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].
     4Trac is extensible with [trac:PluginList plugins] since version 0.9. The plugin functionality is based on the [trac:TracDev/ComponentArchitecture component architecture] with peculiarities described at [TracDev/PluginDevelopment plugin development] page.
    55
    6 == Requirements ==
     6== Plugin discovery ==
     7
     8From the user point of view a Plugin is either standalone .py file or an .egg package. Trac looks for Plugins in a global shared plugins directory (see [TracIni#GlobalConfiguration Global Configuration]), or in a local TracEnvironment, in its `plugins` directory.
     9Except for the later case, the components defined in a plugin should be explicitly enabled in the [[TracIni#components-section| [components] ]] section of the trac.ini file.
     10
     11== Requirements for Trac eggs  ==
    712
    813To use egg based plugins in Trac, you need to have [http://peak.telecommunity.com/DevCenter/setuptools setuptools] (version 0.6) installed.
    9 
    10 Plugins can also consist of a single `.py` file dropped into either the environment or global `plugins` directory ''(since [milestone:0.10])''.
    1114
    1215To install `setuptools`, download the bootstrap module [http://peak.telecommunity.com/dist/ez_setup.py ez_setup.py] and execute it as follows:
     
    1720If 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.
    1821
     22Plugins can also consist of a single `.py` file dropped into either the environment or the shared plugins directory.
     23
    1924== Installing a Trac Plugin ==
    2025
    2126=== For a Single Project ===
    2227
    23 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:
     28Plugins are packaged as [http://peak.telecommunity.com/DevCenter/PythonEggs Python eggs]. That means they are ZIP archives with the file extension `.egg`.
     29
     30If you have downloaded a source distribution of a plugin, and want to build the `.egg` file, follow this instruction:
     31 * Unpack the source. It should provide a setup.py.
     32 * Run:
    2433{{{
    2534$ python setup.py bdist_egg
    2635}}}
    27 to build the `.egg` file.
    2836
    29 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.
     37Then you will have a *.egg file. Examine the output of running python to find where this was created.
     38
     39Once 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).
     40
     41To uninstall a plugin installed this way, remove the egg from `plugins` directory and restart web server.
    3042
    3143Note that the Python version that the egg is built with must
    3244match the Python version with which Trac is run.  If for
    33 instance you are running Trac under Python 2.3, but have
    34 upgraded your standalone Python to 2.4, the eggs won't be
     45instance you are running Trac under Python 2.5, but have
     46upgraded your standalone Python to 2.6, the eggs won't be
    3547recognized.
     48
     49Note 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.
    3650
    3751=== For All Projects ===
     
    3953==== With an .egg file ====
    4054
    41 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:
     55Some plugins (such as [trac:SpamFilter SpamFilter]) are downloadable as a `.egg` file which can be installed with the `easy_install` program:
    4256{{{
    43 easy_install TracWebAdmin-0.1.1dev_r2765-py2.3.egg
     57easy_install TracSpamFilter
    4458}}}
    4559
    46 If `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).
     60If `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:\Python24\Scripts`) to their `PATH` environment variable (see [http://peak.telecommunity.com/DevCenter/EasyInstall#windows-notes easy_install Windows notes] for more information).
    4761
    4862If 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`:
    4963{{{
    50 easy_install --always-unzip TracWebAdmin-0.1.1dev_r2765-py2.3.egg
     64easy_install --always-unzip TracSpamFilter-0.4.1_r10106-py2.6.egg
    5165}}}
    5266You should end up with a directory having the same name as the zipped egg (complete with `.egg` extension) and containing its uncompressed contents.
    5367
    54 Trac also searches for globally installed plugins under `$prefix/share/trac/plugins` ''(since 0.10)''.
     68Trac also searches for plugins installed in the shared plugins directory ''(since 0.10)'', see TracIni#GlobalConfiguration. This is a convenient way to share the installation of plugins across several but not all environments.
    5569
    5670==== From source ====
    5771
    58 If you downloaded the plugin's source from Subversion, or a source zip file you can install it using the included `setup.py`:
     72`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:
    5973{{{
    60 $ python setup.py install
     74easy_install http://svn.edgewall.com/repos/trac/plugins/0.12/spam-filter-captcha
    6175}}}
    6276
    6377==== Enabling the plugin ====
    64 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:
     78Unlike 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 shared plugins directory, i.e. the path specified in the `[inherit] plugins_dir` configuration option.
     79
     80This is done in the `[components]` section of the configuration file, for example:
    6581{{{
    6682[components]
    67 webadmin.* = enabled
     83tracspamfilter.* = enabled
    6884}}}
    6985
    70 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`.)
     86The 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`.)
    7187
    72 Note: After installing the plugin, you may need to restart Apache.
     88Note: After installing the plugin, you need to restart your web server.
     89
     90==== Uninstalling ====
     91
     92`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:
     93 1. Do `easy_install -m [plugin name]` to remove references from `$PYTHONLIB/site-packages/easy-install.pth` when the plugin installed by setuptools.
     94 1. Delete executables from `/usr/bin`, `/usr/local/bin` or `C:\\Python*\Scripts`. For search what executables are there, you may refer to `[console-script]` section of `setup.py`.
     95 1. Delete the .egg file or folder from where it is installed, usually inside `$PYTHONLIB/site-packages/`.
     96 1. Restart web server.
     97
     98If 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):
     99{{{
     100>>> import myplugin
     101>>> print myplugin.__file__
     102/opt/local/python24/lib/site-packages/myplugin-0.4.2-py2.4.egg/myplugin/__init__.pyc
     103}}}
    73104
    74105== Setting up the Plugin Cache ==
    75106
    76 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.
     107Some 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.
    77108
    78109To do this from the Apache configuration, use the `SetEnv` directive as follows:
     
    100131}}}
    101132
    102  ''Note: this requires the `mod_env` module''
     133 ''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.''
    103134
    104 For [wiki:TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
     135For [wiki:TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
     136
     137 ''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.
     138
     139{{{
     140FastCgiConfig -initial-env TRAC_ENV=/var/lib/trac -initial-env PYTHON_EGG_CACHE=/var/lib/trac/plugin-cache
     141}}}
    105142
    106143=== About hook scripts ===
     
    121158=== Did you get the correct version of the Python egg? ===
    122159
    123 Python 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).
     160Python eggs have the Python version encoded in their filename. For example, `MyPlugin-1.0-py2.5.egg` is an egg for Python 2.5, and will '''not''' be loaded if you're running a different Python version (such as 2.4 or 2.6).
    124161
    125162Also, 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.
     
    127164=== Is the plugin enabled? ===
    128165
     166
    129167If 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:
    130168 * you actually added the necessary line(s) to the `[components]` section
    131169 * the package/module names are correct
    132  * if you're reference a module (as opposed to a class), you've appended the necessary “.*”
    133170 * the value is “enabled", not e.g. “enable”
    134171
    135172=== Check the permissions on the egg file ===
    136173
    137 Trac must of course be able to read the file. Yeah, you knew that ;-)
     174Trac must be able to read the file.
    138175
    139176=== Check the log files ===
    140177
    141 Enable [TracLogging logging] in Trac, set the log level to `DEBUG` and then watch the log file for messages about loading plugins.
     178Enable [wiki:TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins.
     179
     180=== Verify you have proper permissions ===
     181
     182Some 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.
     183
     184=== Is the wrong version of the plugin loading? ===
     185
     186If 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:
     187 * 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.
     188 * 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.
     189 * 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.
     190 * 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.
     191
     192=== If all of the above failed ===
     193
     194OK, 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.
    142195
    143196----
    144 See also TracGuide, [http://trac.edgewall.org/wiki/PluginList plugin list], [http://trac.edgewall.org/wiki/TracDev/ComponentArchitecture component architecture]
     197See also TracGuide, [trac:PluginList plugin list], [trac:TracDev/ComponentArchitecture component architecture]