Changes between Version 3 and Version 4 of TracPlugins


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Timestamp:
03/24/24 16:57:05 (9 months ago)
Author:
trac
Comment:

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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 an .egg package. 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.
    10 
    11 == Requirements for Trac eggs #Requirements
    12 
    13 To use egg-based plugins in Trac, you need to have [http://peak.telecommunity.com/DevCenter/setuptools setuptools] (version >= 0.6) installed.
    14 
    15 To install `setuptools`, download the bootstrap module [http://peak.telecommunity.com/dist/ez_setup.py ez_setup.py] and execute it as follows:
    16 
    17 {{{#!sh
    18 $ python ez_setup.py
    19 }}}
    20 
    21 If the `ez_setup.py` script fails to install the setuptools release, you can download it from [pypi:setuptools PyPI] and install it manually.
    22 
    23 Plugins can also consist of a single `.py` file dropped directly into either the project's or the shared `plugins` directory.
     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.
    2410
    2511== Installing a Trac plugin
    2612
    27 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.
    2814
    2915=== For a single project
    3016
    31 If you have downloaded a source distribution of a plugin, and want to build the `.egg` file:
    32 
    33  * Unpack the source. It should provide `setup.py`.
    34  * 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:
    3521 {{{#!sh
    3622$ python setup.py bdist_egg
    3723}}}
    38 
    39 You should now have an *.egg file. Examine the output of running Python to find where this was created.
    40 
    41 Once 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, ie kill the process and run again.
    42 
    43 To uninstall a plugin installed this way, remove the egg from the `plugins` directory and restart the web server.
    44 
    45 '''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.
    46 
    47 '''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.
    4838
    4939=== For all projects
    5040
    51 ==== With an .egg file
    52 
    53 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`:
    54 {{{#!sh
    55 $ easy_install TracTags
     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`:
     50{{{#!sh
    5651$ pip install TracTags
    5752}}}
    5853
    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:\Python27\Scripts`) to their `PATH` environment variable, or use the full path to `easy_install` (for example, `C:\Python27\Scripts\easy_install.py`). See [http://peak.telecommunity.com/DevCenter/EasyInstall#windows-notes easy_install Windows notes] for more information.
    60 
    61 `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].
    62 
    63 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`:
    64 {{{#!sh
    65 $ easy_install --always-unzip TracTags
    66 }}}
    67 You should end up with a directory having the same name as the zipped egg, complete with `.egg` extension, and containing its uncompressed contents.
    68 
    69 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}}}
    7058
    7159==== From source
    7260
    73 `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:
    74 {{{#!sh
    75 $ easy_install https://trac-hacks.org/svn/tagsplugin/trunk
     61You can install directly from a source repository:
     62{{{#!sh
     63$ pip install svn+https://trac-hacks.org/svn/tagsplugin/trunk
     64}}}
     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
    7677}}}
    7778
    7879==== Enabling the plugin
    7980
    80 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 shared plugins directory, ie the path specified in the `[inherit] plugins_dir` configuration option.
     81Unlike plugins installed per environment, you have to explicitly enable globally installed plugins. This also applies to plugins installed in the shared plugins directory.
    8182
    8283This is done in the `[components]` section of the configuration file `trac.ini`. For example:
    … …  
    8687}}}
    8788
    88 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.
    8992
    9093After installing the plugin, you must restart your web server.
    … …  
    9295==== Upgrading the environment
    9396
    94 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:
    9598
    9699{{{#!sh
    … …  
    100103A database backup will be made before upgrading the environment, unless the `--no-backup` option is specified. For more information, refer to the documentation output by `trac-admin /path/to/env help upgrade`.
    101104
    102 ==== Uninstalling
    103 
    104 Neither `easy_install` nor `python setup.py` have an uninstall feature. However, it is usually trivial to remove a globally installed egg and reference:
    105 
    106  1. Do `easy_install -m [plugin name]` to remove references from `$PYTHONLIB/site-packages/easy-install.pth` when the plugin installed by setuptools.
    107  1. Delete executables from `/usr/bin`, `/usr/local/bin`, or `C:\\Python*\Scripts`. To find what executables are involved, refer to the `[console-script]` section of `setup.py`.
    108  1. Delete the .egg file or folder from where it's installed, usually inside `$PYTHONLIB/site-packages/`.
    109  1. Restart the web server.
    110 
    111 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):
    112 {{{#!pycon
    113 >>> import myplugin
    114 >>> print myplugin.__file__
    115 /opt/local/python24/lib/site-packages/myplugin-0.4.2-py2.4.egg/myplugin/__init__.pyc
    116 }}}
     105==== Redeploying static resources
     106
     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]:
     110
     111{{{#!sh
     112$ trac-admin /path/to/env deploy /deploy/path
     113}}}
     114
     115After executing the command, you must restart your web server.
     116
     117{{{#!div style="border: 1pt dotted; margin: 1em"
     118**Note:** Some web browsers (IE, Opera) cache CSS and Javascript files, so you should instruct your users to manually erase the contents of their browser's cache. A forced refreshed (SHIFT + <F5>) should be enough.
     119{{{#!comment
     120Remove above note once #9936 is fixed.
     121}}}
     122}}}
     123
     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}}}
     144
     145== Web-based plugin administration
     146
     147The admin page offers limited support for plugin configuration to users with `TRAC_ADMIN` permission:
     148
     149* en/dis-abling installed plugins
     150* installing plugins by uploading them as eggs
     151
     152If you wish to disable the second function for security reasons, add the following to your `trac.ini` file:
     153{{{#!ini
     154[components]
     155trac.admin.web_ui.PluginAdminPanel = disabled
     156}}}
     157This disables the whole panel, so the first function will no longer be available.
    117158
    118159== Setting up the plugin cache
    119160
    120 Some plugins 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 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.
     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.
    121162
    122163To do this from the Apache configuration, use the `SetEnv` directive:
    … …  
    125166}}}
    126167
    127 This 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], ie in the same `<Location>` block.
     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.
    128169
    129170For example for CGI:
    … …  
    146187'''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.
    147188
    148 For [wiki:TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
     189For [TracFastCgi FastCGI], you will need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
    149190
    150191'''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:
    … …  
    156197=== About hook scripts
    157198
    158 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.
    159 
    160 == Web-based plugin administration
    161 
    162 The [trac:WebAdmin] interface offers limited support for plugin configuration through the web to users with `TRAC_ADMIN` permission:
    163 
    164 * en/disabling installed plugins
    165 * installing plugins by uploading them as eggs
    166 
    167 If you wish to disable the second function for security reasons, add the following to your `trac.ini` file:
    168 {{{#!ini
    169 [components]
    170 trac.admin.web_ui.PluginAdminPanel = disabled
    171 }}}
    172 This disables the whole panel, so the first function will no longer be available either.
     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]
    173207
    174208== Troubleshooting
    175209
    176 === Is setuptools properly installed?
    177 
    178 Try this from the command line:
    179 {{{#!sh
    180 $ python -c "import pkg_resources"
    181 }}}
    182 
    183 If you get '''no output''', setuptools '''is''' installed. Otherwise, you'll need to install it before plugins will work in Trac.
    184 
    185210=== Did you get the correct version of the Python egg?
    186211
    187 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).
    188 
    189 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.
    190215
    191216=== Is the plugin enabled?
    192217
    193 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:
    194 
    195  * 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.
    196221 * the package/module names are correct and do not contain typos.
    197  * the value is "enabled", not "enable" or "Enable".
    198  * the section name is "components", not "component".
    199 
    200 === Check the permissions on the .egg file
    201 
    202 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).
    203228
    204229=== Check the log files
    205230
    206 Enable [wiki:TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins.
     231See [trac:TracTroubleshooting#ChecktheLogs].
    207232
    208233=== Verify you have the proper permissions
    209234
    210 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.
     235Some plugins require you have special permissions. !TracTags, for example, requires `TAGS_VIEW` permissions for the //Tags// navigation item to be added.
    211236
    212237=== Is the wrong version of the plugin loading?
    213238
    214 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:
    215 
    216  * 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.
    217  * 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.
    218  * 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.
    219  * 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.
    220245
    221246=== If all of the above failed
    222247
    223 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] and ask away!
     248See TracSupport.
    224249
    225250----
    226 See also TracGuide, [trac:PluginList plugin list], [trac:TracDev/ComponentArchitecture component architecture].
     251See also TracGuide, TracIni.