Changes between Version 3 and Version 4 of TracPlugins


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Timestamp:
Jan 3, 2024, 10:40:13 AM (5 months ago)
Author:
trac
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  • TracPlugins

    v3 v4  
    33= Trac plugins
    44
    5 Trac is extensible with [trac:PluginList plugins]. Plugin functionality is based on the [trac:TracDev/ComponentArchitecture component architecture], with special cases described in the [trac:TracDev/PluginDevelopment plugin development] page.
     5Trac is extensible with [trac:PluginList plugins]. Plugin functionality is based on the [trac:TracDev/ComponentArchitecture component architecture], described in the [trac:TracDev/PluginDevelopment plugin development] page.
    66
    77== Plugin discovery
    88
    9 From the user's point of view, a plugin is either a standalone .py file or a package (egg or wheel). Trac looks for plugins in Python's `site-packages` directory, the [TracIni#GlobalConfiguration global shared] `plugins` directory and the [TracEnvironment project environment] `plugins` directory. Components defined in globally-installed plugins must be explicitly enabled in the [[TracIni#components-section| [components] ]] section of the `trac.ini` file. Components defined in the `plugins` directory of the project environment are enabled, unless explicitly disabled in the `[components]` section of the `trac.ini` file.
     9A plugin is either a single .py file or a package (.egg or .whl). Trac looks for plugins in Python's `site-packages` directory, the [TracIni#GlobalConfiguration global shared] `plugins` directory and the [TracEnvironment project environment] `plugins` directory. Plugins installed to the project environment `plugins` directory are enabled, unless explicitly disabled in the `[components]` section of the `trac.ini` file. Plugins installed elsewhere must be explicitly enabled in the [TracIni#components-section "[components]"] section of the `trac.ini` file.
    1010
    1111== Installing a Trac plugin
    1212
    13 The instructions below are applicable to a plugin packaged as an egg. Plugins implemented as a single `py` file should be downloaded and copied to the [TracEnvironment project environment] `plugins` directory or the [TracIni#GlobalConfiguration global shared] plugins directory.
     13The instructions below are applicable to plugins installed as packages. Plugins implemented as a single `py` file should be downloaded and copied to the [TracEnvironment project environment] `plugins` directory or the [TracIni#GlobalConfiguration global shared] plugins directory.
    1414
    1515=== For a single project
    1616
    17 If you have downloaded a source distribution of a plugin, and want to build the `.egg` file:
    18 
    19  * Unpack the source. It should provide `setup.py`.
    20  * Run:
     17Packages built for a single project must use the egg format, as the wheel format (described below) is not supported by the setuptools loading mechanism. Build the `egg` file from the plugin source:
     18
     19* Checkout or download and unpack the source.
     20* Change to the directory containing `setup.py` and run:
    2121 {{{#!sh
    2222$ python setup.py bdist_egg
    2323}}}
    24 
    25 You should now have an *.egg file. Examine the output of running Python to find where this was created.
    26 
    27 Once you have the plugin archive, copy it into the `plugins` directory of the [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 [TracStandalone "tracd" standalone server], restart tracd, ie kill the process and run again.
    28 
    29 To uninstall a plugin installed this way, remove the egg from the `plugins` directory and restart the web server.
    30 
    31 '''Note''': the Python version that the egg is built with ''must'' match the Python version with which Trac is run. For example, if you are running Trac under Python 2.6, but have upgraded your standalone Python to 2.7, the eggs won't be recognized.
    32 
    33 '''Note''': 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.
     24 The egg file will be created in the `dist` subdirectory.
     25* Copy the egg file to the `plugins` directory of the [TracEnvironment project environment].
     26
     27Make sure the web server has sufficient permissions to read the plugin egg and restart the web server. If you are running as a [TracStandalone "tracd" standalone server], restart tracd, i.e. kill the process and run again.
     28
     29Trac also searches for plugins installed in the [TracIni#GlobalConfiguration global shared] plugins directory. This is a convenient way to share the installation of plugins across several, but not all, environments.
     30
     31'''Note''': The minor version number of the Python used to build the egg ''must'' match the minor version number of the Python running Trac. For example, if you are running Trac with Python 2.6, but build the egg with Python 2.7, the egg won't be recognized.
     32
     33'''Note''': In a multi-project setup, a pool of Python interpreters 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 plugin in different projects of a multi-project setup. Install plugins for all projects (see below) and enable them as needed for each project.
     34
     35==== Uninstalling #UninstallEgg
     36
     37Remove the egg from the `plugins` directory and restart the web server.
    3438
    3539=== For all projects
    3640
    37 ==== With an .egg file
    38 
    39 Some plugins, such as [https://trac-hacks.org/wiki/TagsPlugin TracTags], are downloadable as an `.egg` file that can be installed with `easy_install` or `pip`:
    40 {{{#!sh
    41 $ easy_install TracTags
    42 }}}
     41==== Using pip
     42
     43The modern Python package manager, `pip`, is included in Python 2.7.9 and later. In earlier versions of Python it can be installed through the package manager of your OS (e.g. `apt-get install python-pip`) or using [https://pip.pypa.io/en/latest/installing.html#install-pip get_pip.py].
     44
     45Using `pip`, the plugin will be installed in the [https://pythonwheels.com/ wheel format], which is the modern standard for Python and a replacement for the egg format.
     46
     47==== From PyPI
     48
     49Some plugins, such as [https://trac-hacks.org/wiki/TagsPlugin TracTags], can be installed directly from [https://pypi.org PyPI] using `pip`:
    4350{{{#!sh
    4451$ pip install TracTags
    4552}}}
    4653
    47 If `easy_install` is not on your system, see the [trac:setuptools#Installsetuptools Trac setuptools documentation].
    48 
    49 `pip` is included in Python 2.7.9. In earlier versions of Python it can be installed through the package manager of your OS (e.g. `apt-get install python-pip`) or using the [https://pip.pypa.io/en/latest/installing.html#install-pip get_pip.py].
    50 
    51 If Trac reports permission errors after installing a zipped egg, and you would rather not bother providing an 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`:
    52 {{{#!sh
    53 $ easy_install --always-unzip TracTags
    54 }}}
    55 You should end up with a directory having the same name as the zipped egg, complete with `.egg` extension, and containing its uncompressed contents.
    56 
    57 Trac also searches for plugins installed in the shared plugins directory, see TracIni#GlobalConfiguration. This is a convenient way to share the installation of plugins across several, but not all, environments.
     54The version can be specified, which can be useful if you don't want to install the latest:
     55{{{#!sh
     56$ pip install TracTags==1.2
     57}}}
    5858
    5959==== From source
    6060
    61 `easy_install` and `pip` make installing from source a snap. Just give it the URL to either a repository or a tarball/zip of the source:
    62 {{{#!sh
    63 $ easy_install https://trac-hacks.org/svn/tagsplugin/trunk
    64 }}}
     61You can install directly from a source repository:
    6562{{{#!sh
    6663$ pip install svn+https://trac-hacks.org/svn/tagsplugin/trunk
    6764}}}
    68 When installing from a repository using `pip`, be sure to use the repository type in the protocol. For example, `svn+https` for Subversion and `git+https` for Git.
     65
     66Replace the `svn+` prefix with `git+` if installing from a Git repository.
     67
     68Or from the path or URL of a tar.gz or zip archive:
     69{{{#!sh
     70$ pip install https://trac-hacks.org/browser/tagsplugin/trunk?format=zip
     71}}}
     72
     73Or checkout the source and provide `pip` a path to the source directory:
     74{{{#!sh
     75$ svn co https://trac-hacks.org/svn/tagsplugin/trunk tractags
     76$ pip install tractags
     77}}}
    6978
    7079==== Enabling the plugin
    7180
    72 Unlike plugins installed per environment, you'll have to explicitly enable globally installed plugins via [TracIni trac.ini]. This also applies to plugins installed in the shared plugins directory, ie the path specified in the [TracIni#inherit-plugins_dir-option "[inherit] plugins_dir"] configuration option.
    73 
    74 This is done in the [TracIni#components-section "[components]"] section of the configuration file `trac.ini`. For example:
     81Unlike plugins installed per environment, you have to explicitly enable globally installed plugins. This also applies to plugins installed in the shared plugins directory.
     82
     83This is done in the `[components]` section of the configuration file `trac.ini`. For example:
    7584{{{#!ini
    7685[components]
     
    7887}}}
    7988
    80 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`.
     89The name of the option is the plugin package name. This should be specified in the documentation of the plugin, but can also be discovered by looking at the source: it is usually the top-level directory name containing a file named `__init__.py`.
     90
     91Plugins can also be enabled from the [#Web-basedpluginadministration administration] page.
    8192
    8293After installing the plugin, you must restart your web server.
     
    8495==== Upgrading the environment
    8596
    86 Some plugins may require an environment upgrade. This will typically be necessary for plugins that implement `IEnvironmentSetupParticipant`. Common reasons for requiring an environment upgrade are to add tables to the database or add configuration parameters to trac.ini. A notification will be displayed when accessing Trac for the first time after installing a plugin and restarting the web server. To upgrade the environment, run the command:
     97Some plugins require an environment upgrade. This will typically be necessary for plugins that implement `IEnvironmentSetupParticipant`. Common reasons for requiring an environment upgrade are to add tables to the database or add configuration parameters to `trac.ini`. A notification will be displayed when accessing Trac for the first time after installing a plugin and restarting the web server. To upgrade the environment, run the command:
    8798
    8899{{{#!sh
     
    94105==== Redeploying static resources
    95106
    96 If you [TracInstall#MappingStaticResources mapped static resources] so they are served by the web server, and the plugin contains static resources (CSS, !JavaScript and image files), the resources will need to be deployed to the location on the filesystem that is served by the web server.
    97 
    98 Execute the `deploy` command, as was done during install and [TracUpgrade#a5.Refreshstaticresources upgrade]:
     107If you [TracInstall#MappingStaticResources mapped static resources] so they are served by the web server, and the plugin contains static resources, such as stylesheets, !JavaScript and image files, the resources will need to be deployed to the location on the filesystem that is served by the web server.
     108
     109Execute the `deploy` command, as is done during install and [TracUpgrade#a5.Refreshstaticresources upgrade]:
    99110
    100111{{{#!sh
     
    111122}}}
    112123
    113 ==== Upgrading a Plugin
    114 
    115 Normally, upgrading a plugin is simply a matter of repeating the install process. You may want to [#Uninstalling uninstall] old versions of the plugin.
    116 
    117 The `pip install` command has an `--upgrade (-U)` switch that will uninstall the old version and install the new version. The command can have some unintended side-effects though, because it will also upgrade the plugin dependencies. For example, if `Trac` is listed as a dependency of the plugin in `setup.py`, the latest version of Trac will be downloaded and installed. This may not be what you want if you are running an older version of Trac because not all your plugins are compatible with the latest version of Trac, or you simply haven't done the appropriate planning for upgrading Trac. Uninstalling and then installing the plugin can be a safer option:
    118 {{{#!sh
    119 $ pip uninstall <pluginname>
    120 $ pip install <pluginname>
    121 }}}
    122 
    123 Alternatively you can use a [https://pip.pypa.io/en/stable/user_guide/#requirements-files requirements file] and pin the versions of the packages that you don't want to implicitly upgrade.
    124 
    125 ==== Uninstalling
    126 
    127 `pip` makes it easy to uninstall a plugin:
    128 {{{#!sh
    129 $ pip uninstall <pluginname>
    130 }}}
    131 
    132 The `pip uninstall` command can be used even if the plugin was installed using `easy_install` or `python setup.py install`.
    133 
    134 Neither `easy_install` nor `python setup.py` have an uninstall feature. However, it is usually trivial to remove a globally installed egg and reference:
    135 
    136  1. Do `easy_install -m <plugin name>` to remove references from `$PYTHONLIB/site-packages/easy-install.pth` when the plugin is installed by setuptools.
    137  1. Delete executables from `/usr/bin`, `/usr/local/bin`, or `C:\\Python*\Scripts`. To find what executables are involved, refer to the `[console-script]` section of `setup.py`.
    138  1. Delete the .egg file or folder from where it's installed, usually inside `$PYTHONLIB/site-packages/`.
    139  1. Restart the web server.
    140 
    141 If you are uncertain about the location of the egg file, you can try to locate it by replacing `myplugin` with whatever namespace the plugin uses (as used when enabling the plugin):
    142 {{{#!pycon
    143 >>> import myplugin
    144 >>> print myplugin.__file__
    145 /opt/local/python24/lib/site-packages/myplugin-0.4.2-py2.4.egg/myplugin/__init__.pyc
    146 }}}
    147 
    148 == Setting up the plugin cache
    149 
    150 Some plugins will need to be extracted by the Python egg's runtime. See [wiki:TracInstall#egg-cache] for information on setting up the egg cache.
     124==== Uninstalling #UninstallWithPip
     125
     126Get a list of installed plugins:
     127{{{#!sh
     128$ pip list
     129Package    Version
     130---------- -------
     131Jinja2     2.10.1
     132MarkupSafe 1.1.1
     133pip        19.2.2
     134setuptools 41.2.0
     135Trac       1.4
     136TracTags   0.10
     137wheel      0.33.6
     138}}}
     139
     140Uninstall a plugin by specifying the package name:
     141{{{#!sh
     142$ pip uninstall TracTags
     143}}}
    151144
    152145== Web-based plugin administration
    153146
    154 The !WebAdmin interface offers limited support for plugin configuration to users with `TRAC_ADMIN` permission:
    155 
    156 * enabling and disabling installed plugins
     147The admin page offers limited support for plugin configuration to users with `TRAC_ADMIN` permission:
     148
     149* en/dis-abling installed plugins
    157150* installing plugins by uploading them as eggs
    158151
     
    162155trac.admin.web_ui.PluginAdminPanel = disabled
    163156}}}
    164 This disables the whole panel, so the first function will no longer be available either.
     157This disables the whole panel, so the first function will no longer be available.
     158
     159== Setting up the plugin cache
     160
     161Some plugins installed as eggs will need to be extracted by the Python egg's runtime (`pkg_resources`), so that their contents are actual files on the file system. The directory to 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.
     162
     163To do this from the Apache configuration, use the `SetEnv` directive:
     164{{{#!apache
     165SetEnv PYTHON_EGG_CACHE /path/to/dir
     166}}}
     167
     168This works whether you're using the [TracCgi CGI] or the [TracModPython mod_python] front-end. Put this directive next to where you set the path to the [TracEnvironment Trac environment], i.e. in the same `<Location>` block.
     169
     170For example for CGI:
     171{{{#!apache
     172 <Location /trac>
     173   SetEnv TRAC_ENV /path/to/projenv
     174   SetEnv PYTHON_EGG_CACHE /path/to/dir
     175 </Location>
     176}}}
     177
     178Or for mod_python:
     179{{{#!apache
     180 <Location /trac>
     181   SetHandler mod_python
     182   ...
     183   SetEnv PYTHON_EGG_CACHE /path/to/dir
     184 </Location>
     185}}}
     186
     187'''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.
     188
     189For [TracFastCgi FastCGI], you will need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
     190
     191'''Note''': 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:
     192
     193{{{#!apache
     194FastCgiConfig -initial-env TRAC_ENV=/var/lib/trac -initial-env PYTHON_EGG_CACHE=/var/lib/trac/plugin-cache
     195}}}
     196
     197=== About hook scripts
     198
     199If you have Subversion hook scripts that invoke Trac, 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.
     200
     201== Writing Trac Plugins
     202
     203You can write your own Trac plugin using the following resources:
     204* [trac:TracDev Developer documentation]
     205* [https://trac-hacks.org Examples on trac-hacks.org]
     206* [trac:browser:branches/1.4-stable/sample-plugins sample-plugins]
    165207
    166208== Troubleshooting
    167209
    168 === Is setuptools properly installed?
    169 
    170 Try this from the command line:
    171 {{{#!sh
    172 $ python -c "import pkg_resources"
    173 }}}
    174 
    175 If you get '''no output''', setuptools '''is''' installed. Otherwise, you'll need to install it before plugins will work in Trac.
    176 
    177210=== Did you get the correct version of the Python egg?
    178211
    179 Python 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).
    180 
    181 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.
     212Python 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.
     213
     214Also, verify that the egg file you downloaded is indeed a .zip archive. If you downloaded it from a Trac site, you may have downloaded the HTML preview page instead.
    182215
    183216=== Is the plugin enabled?
    184217
    185 If you install a plugin globally, ie ''not'' inside the `plugins` directory of the Trac project environment, you must explicitly enable it in [TracIni trac.ini]. Make sure that:
    186 
    187  * you actually added the necessary line(s) to the `[components]` section.
     218If 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:
     219
     220 * you added the necessary line(s) to the `[components]` section.
    188221 * the package/module names are correct and do not contain typos.
    189  * the value is "enabled", not "enable" or "Enable".
    190  * the section name is "components", not "component".
    191 
    192 === Check the permissions on the .egg file
    193 
    194 Trac must be able to read the .egg file.
     222 * the value is `enabled`, not `enable` or `Enable`.
     223 * the section name is `components`, not `component`.
     224
     225=== Check the permissions
     226
     227Trac must be able to read the .py file or package (.egg or .whl).
    195228
    196229=== Check the log files
    197230
    198 Enable [TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins.
     231See [trac:TracTroubleshooting#ChecktheLogs].
    199232
    200233=== Verify you have the proper permissions
    201234
    202 Some plugins require you have special permissions in order to use them. !WebAdmin, for example, requires the user to have `TRAC_ADMIN` permissions for it to show up on the navigation bar.
     235Some plugins require you have special permissions. !TracTags, for example, requires `TAGS_VIEW` permissions for the //Tags// navigation item to be added.
    203236
    204237=== Is the wrong version of the plugin loading?
    205238
    206 If you put your plugins inside the `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:
    207 
    208  * 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.
    209  * 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.
    210  * 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 unpredicatable 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.
    211  * Having more than one version listed inside Python site-packages is fine, ie installed with `setup.py install`, because 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 the version number nor the 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.
     239If you put your plugins in one of the `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:
     240
     241* 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.
     242* A globally installed plugin will override any version in the global or project plugins directories. A plugin from the global plugins directory will be discovered ''before'' any project plugins directory.
     243* 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 unpredictable 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.
     244* Having more than one version listed inside Python site-packages is fine, because 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 the version number nor the 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.
    212245
    213246=== If all of the above failed
    214247
    215 Okay, 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] or [trac:MailingList] and ask away!
     248See TracSupport.
    216249
    217250----
    218 See also TracGuide, [trac:PluginList plugin list], [trac:TracDev/ComponentArchitecture component architecture].
     251See also TracGuide, TracIni.