Changes between Version 4 and Version 5 of TracPlugins


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Timestamp:
May 11, 2012, 10:43:20 AM (3 years ago)
Author:
trac
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  • TracPlugins

    v4 v5  
    1 = Trac Plugins =
     1= Trac plugins =
    22[[TracGuideToc]]
    33
    4 Trac 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.
     4From version 0.9 onwards, Trac is extensible with [trac:PluginList plugins]. Plugin functionality is based on the [trac:TracDev/ComponentArchitecture component architecture], with peculiarities described in the [TracDev/PluginDevelopment plugin development] page.
    55
    66== Plugin discovery ==
    77
    8 From 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]) and in `plugins` directory of local TracEnvironment. Components defined in globally installed plugins should be explicitly enabled in the [[TracIni#components-section| [components] ]] section of the trac.ini file.
    9 
    10 == Requirements for Trac eggs  ==
    11 
    12 To use egg based plugins in Trac, you need to have [http://peak.telecommunity.com/DevCenter/setuptools setuptools] (version 0.6) installed.
     8From the user's point of view, a plugin is either a standalone .py file or an .egg package. Trac looks for plugins in the global shared plugins directory (see [TracIni#GlobalConfiguration Global Configuration]) and in the `plugins` directory of the local TracEnvironment. Components defined in globally-installed plugins should be explicitly enabled in the [[TracIni#components-section| [components] ]] section of the trac.ini file.
     9
     10== Requirements for Trac eggs ==
     11
     12To use egg-based plugins in Trac, you need to have [http://peak.telecommunity.com/DevCenter/setuptools setuptools] (version 0.6) installed.
    1313
    1414To install `setuptools`, download the bootstrap module [http://peak.telecommunity.com/dist/ez_setup.py ez_setup.py] and execute it as follows:
     15
    1516{{{
    1617$ python ez_setup.py
     
    1920If 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.
    2021
    21 Plugins can also consist of a single `.py` file dropped directly into the root of environment's or into shared `plugins` directory.
    22 
    23 == Installing a Trac Plugin ==
    24 
    25 === For a Single Project ===
    26 
    27 Plugins are packaged as [http://peak.telecommunity.com/DevCenter/PythonEggs Python eggs]. That means they are ZIP archives with the file extension `.egg`.
    28 
    29 If you have downloaded a source distribution of a plugin, and want to build the `.egg` file, follow this instruction:
    30  * Unpack the source. It should provide a setup.py.
     22Plugins can also consist of a single `.py` file dropped directly into either the project's or the shared `plugins` directory.
     23
     24== Installing a Trac plugin ==
     25
     26=== For a single project ===
     27
     28Plugins are typically 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:
     31
     32 * Unpack the source. It should provide `setup.py`.
    3133 * Run:
     34
    3235{{{
    3336$ python setup.py bdist_egg
    3437}}}
    3538
    36 Then you will have a *.egg file. Examine the output of running python to find where this was created.
    37 
    38 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).
    39 
    40 To uninstall a plugin installed this way, remove the egg from `plugins` directory and restart web server.
    41 
    42 Note that the Python version that the egg is built with must
    43 match the Python version with which Trac is run.  If for
    44 instance you are running Trac under Python 2.5, but have
    45 upgraded your standalone Python to 2.6, the eggs won't be
    46 recognized.
    47 
    48 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.
    49 
    50 === For All Projects ===
     39You should have a *.egg file. Examine the output of running python to find where this was created.
     40
     41Once you have the plugin archive, 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. If you are running as a [wiki:TracStandalone "tracd" standalone server], restart tracd (kill and run again).
     42
     43To uninstall a plugin installed this way, remove the egg from the `plugins` directory and restart the web server.
     44
     45Note: the Python version that the egg is built with ''must'' match the Python version with which Trac is run. For example, if you're running Trac under Python 2.5, but have upgraded your standalone Python to 2.6, the eggs won't be recognized.
     46
     47Note also: in a multi-project setup, a pool of Python interpreter instances will be dynamically allocated to projects based on need; 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 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.
     48
     49=== For all projects ===
    5150
    5251==== With an .egg file ====
    5352
    54 Some plugins (such as [trac:SpamFilter SpamFilter]) are downloadable as a `.egg` file which can be installed with the `easy_install` program:
     53Some plugins (such as [trac:SpamFilter SpamFilter]) are downloadable as an `.egg` file that can be installed with the `easy_install` program:
    5554{{{
    5655easy_install TracSpamFilter
    5756}}}
    5857
    59 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:\Python24\Scripts`) to their `PATH` environment variable (see [http://peak.telecommunity.com/DevCenter/EasyInstall#windows-notes easy_install Windows notes] for more information).
    60 
    61 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`:
     58If `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).
     59
     60If 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`:
    6261{{{
    6362easy_install --always-unzip TracSpamFilter-0.4.1_r10106-py2.6.egg
     
    6564You should end up with a directory having the same name as the zipped egg (complete with `.egg` extension) and containing its uncompressed contents.
    6665
    67 Trac 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.
     66Trac 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.
    6867
    6968==== From source ====
     
    7574
    7675==== Enabling the plugin ====
    77 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 shared plugins directory, i.e. the path specified in the `[inherit] plugins_dir` configuration option.
    78 
    79 This is done in the `[components]` section of the configuration file, for example:
     76
     77Unlike 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 shared plugins directory, i.e. the path specified in the `[inherit] plugins_dir` configuration option.
     78
     79This is done in the `[components]` section of the configuration file. For example:
    8080{{{
    8181[components]
     
    8383}}}
    8484
    85 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`.)
    86 
    87 Note: After installing the plugin, you need to restart your web server.
     85The 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`).
     86
     87Note: After installing the plugin, you must restart your web server.
    8888
    8989==== Uninstalling ====
    9090
    91 `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:
     91`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:
     92
    9293 1. Do `easy_install -m [plugin name]` to remove references from `$PYTHONLIB/site-packages/easy-install.pth` when the plugin installed by setuptools.
    93  1. Delete executables from `/usr/bin`, `/usr/local/bin` or `C:\\Python*\Scripts`. For search what executables are there, you may refer to `[console-script]` section of `setup.py`.
    94  1. Delete the .egg file or folder from where it is installed, usually inside `$PYTHONLIB/site-packages/`.
    95  1. Restart web server.
    96 
    97 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):
     94 1. Delete executables from `/usr/bin`, `/usr/local/bin`, or `C:\\Python*\Scripts`. To find what executables are involved, refer to the `[console-script]` section of `setup.py`.
     95 1. Delete the .egg file or folder from where it's installed (usually inside `$PYTHONLIB/site-packages/`).
     96 1. Restart the web server.
     97
     98If you are uncertain about the location of the egg, here's a small tip to help locate an egg (or any package). Just replace `myplugin` with whatever namespace the plugin uses (as used when enabling the plugin):
    9899{{{
    99100>>> import myplugin
     
    102103}}}
    103104
    104 == Setting up the Plugin Cache ==
    105 
    106 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.
    107 
    108 To do this from the Apache configuration, use the `SetEnv` directive as follows:
     105== Setting up the plugin cache ==
     106
     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.
     108
     109To do this from the Apache configuration, use the `SetEnv` directive:
    109110{{{
    110111SetEnv PYTHON_EGG_CACHE /path/to/dir
    111112}}}
    112113
    113 This 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.
     114This works whether you're 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.
    114115
    115116For example (for CGI):
     
    121122}}}
    122123
    123 or (for mod_python):
     124Or (for mod_python):
    124125{{{
    125126 <Location /trac>
     
    142143=== About hook scripts ===
    143144
    144 If 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.
     145If you've 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.
    145146
    146147== Troubleshooting ==
     
    159160Python 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).
    160161
    161 Also, 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.
     162Also, 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.
    162163
    163164=== Is the plugin enabled? ===
    164165
    165 
    166 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:
    167  * you actually added the necessary line(s) to the `[components]` section
    168  * the package/module names are correct
    169  * the value is “enabled", not e.g. “enable”
    170 
    171 === Check the permissions on the egg file ===
    172 
    173 Trac must be able to read the file.
     166If you install a plugin globally (i.e., ''not'' inside the `plugins` directory of the Trac project environment), you must explicitly enable it in [TracIni trac.ini]. Make sure that:
     167
     168 * ...you actually added the necessary line(s) to the `[components]` section.
     169 * ...the package/module names are correct.
     170 * ...the value is "enabled", not "enable" or "Enable".
     171
     172=== Check the permissions on the .egg file ===
     173
     174Trac must be able to read the .egg file.
    174175
    175176=== Check the log files ===
     
    184185
    185186If 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:
    186  * 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.
    187  * 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.
    188  * 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.
    189  * 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.
     187
     188 * Only one version of the plugin can be loaded for each running Trac server (i.e., 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.
     189 * A globally-installed plugin (typically `setup.py install`) will override any version in the global or project plugins directories. A plugin from the global plugins directory will be located ''before'' any project plugins directory.
     190 * If your Trac server hosts more than one project (as with `TRAC_ENV_PARENT_DIR` setups), 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 plugin found, usually from the project that receives the first request.
     191 * Having more than one version listed inside Python site-packages is fine (i.e., 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.
    190192
    191193=== If all of the above failed ===
    192194
    193 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.
     195Okay, 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 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!
     196
     197== Web-based plugin administration ==
     198
     199The WebAdmin plugin (part of the core since 0.11) offers limited support for plugin configuration through the web to users with `TRAC_ADMIN` permission:
     200
     201* en/disabling installed plugins
     202* installing plugins by uploading them as eggs
     203
     204You probably want to disable the second function for security reasons: in `trac.ini`, in the `[components]` section, add the line
     205{{{
     206trac.admin.web_ui.PluginAdminPanel = disabled
     207}}}
     208This disables the whole panel, so the first function will no longer be available either.
    194209
    195210----
    196 See also TracGuide, [trac:PluginList plugin list], [trac:TracDev/ComponentArchitecture component architecture]
     211See also TracGuide, [trac:PluginList plugin list], [trac:TracDev/ComponentArchitecture component architecture].