Changes between Version 3 and Version 4 of TracPlugins


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Timestamp:
2023-04-20T18:31:29Z (19 months ago)
Author:
trac
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  • TracPlugins

    v3 v4  
    1 = Trac Plugins =
    2 [[TracGuideToc]]
    3 
    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].
    5 
    6 == Requirements ==
    7 
    8 To use egg based plugins in Trac, you need to have [http://peak.telecommunity.com/DevCenter/setuptools setuptools] (version 0.6) installed.
    9 
    10 To install `setuptools`, download the bootstrap module [http://peak.telecommunity.com/dist/ez_setup.py ez_setup.py] and execute it as follows:
    11 {{{
    12 $ python ez_setup.py
    13 }}}
    14 
    15 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.
    16 
    17 Plugins can also consist of a single `.py` file dropped into either the environment or global `plugins` directory ''(since [milestone:0.10])''.
    18 
    19 == Installing a Trac Plugin ==
    20 
    21 === For a Single Project ===
    22 
    23 Plugins are packaged as [http://peak.telecommunity.com/DevCenter/PythonEggs Python eggs]. That means they are ZIP archives with the file extension `.egg`.
    24 
    25 If you have downloaded a source distribution of a plugin, and want to build the `.egg` file, follow this instruction:
    26  * Unpack the source. It should provide a setup.py.
    27  * Run:
    28 {{{
     1[[PageOutline(2-5,Contents,pullout)]]
     2
     3= Trac plugins
     4
     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.
     6
     7== Plugin discovery
     8
     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.
     10
     11== Installing a Trac plugin
     12
     13The instructions below are applicable to a 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.
     14
     15=== For a single project
     16
     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:
     21 {{{#!sh
    2922$ python setup.py bdist_egg
    3023}}}
    31 
    32 Then you will have a *.egg file. Examine the output of running python to find where this was created.
    33 
    34 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.
    35 
    36 Note that the Python version that the egg is built with must
    37 match the Python version with which Trac is run.  If for
    38 instance you are running Trac under Python 2.3, but have
    39 upgraded your standalone Python to 2.4, the eggs won't be
    40 recognized.
    41 
    42 === For All Projects ===
    43 
    44 ==== With an .egg file ====
    45 
    46 Some plugins (such as [http://trac.edgewall.org/wiki/SpamFilter SpamFilter]) are downloadable as a `.egg` file which can be installed with the `easy_install` program:
    47 {{{
    48 easy_install TracSpamFilter
    49 }}}
    50 
    51 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).
    52 
    53 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`:
    54 {{{
    55 easy_install --always-unzip TracSpamFilter-0.2.1dev_r5943-py2.4.egg
    56 }}}
    57 You should end up with a directory having the same name as the zipped egg (complete with `.egg` extension) and containing its uncompressed contents.
    58 
    59 Trac also searches for globally installed plugins under `$PREFIX/share/trac/plugins` ''(since 0.10)''.
    60 
    61 ==== From source ====
    62 
    63 `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:
    64 {{{
    65 easy_install http://svn.edgewall.com/repos/trac/sandbox/spam-filter
    66 }}}
    67 
    68 ==== Enabling the plugin ====
    69 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:
    70 {{{
     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.
     38
     39=== For all projects
     40
     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
     46in the [https://pythonwheels.com/ wheel format], which is the modern standard for Python and a
     47replacement for the egg format.
     48
     49==== From PyPI
     50
     51Some plugins, such as [https://trac-hacks.org/wiki/TagsPlugin TracTags], can be installed directly from [https://pypi.org PyPI] using `pip`:
     52{{{#!sh
     53$ pip install TracTags
     54}}}
     55
     56The version can be specified, which can be useful if you don't want to install the latest:
     57{{{#!sh
     58$ pip install TracTags==0.10
     59}}}
     60
     61==== From source
     62
     63You can install directly from a source repository:
     64{{{#!sh
     65$ pip install svn+https://trac-hacks.org/svn/tagsplugin/trunk
     66}}}
     67
     68Replace the `svn+` prefix with `git+` if installing
     69from a Git repository.
     70
     71Or from the path or URL of a tar.gz or zip archive:
     72{{{#!sh
     73$ pip install https://trac-hacks.org/browser/tagsplugin/trunk?format=zip
     74}}}
     75
     76Or checkout the source and provide `pip` a path to the source directory:
     77{{{#!sh
     78$ svn co https://trac-hacks.org/svn/tagsplugin/trunk tractags
     79$ pip install tractags
     80}}}
     81
     82==== Enabling the plugin
     83
     84Unlike plugins installed per environment, you have to explicitly enable globally installed plugins. This also applies to plugins installed in the shared plugins directory.
     85
     86This is done in the `[components]` section of the configuration file `trac.ini`. For example:
     87{{{#!ini
    7188[components]
    72 tracspamfilter.* = enabled
    73 }}}
    74 
    75 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`.)
    76 
    77 Note: After installing the plugin, you need to restart your web server.
    78 
    79 == Setting up the Plugin Cache ==
    80 
    81 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.
    82 
    83 To do this from the Apache configuration, use the `SetEnv` directive as follows:
    84 {{{
     89tractags.* = enabled
     90}}}
     91
     92The 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`.
     93
     94Plugins can also be enabled from the [#Web-basedpluginadministration administration] page.
     95
     96After installing the plugin, you must restart your web server.
     97
     98==== Upgrading the environment
     99
     100Some 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:
     101
     102{{{#!sh
     103$ trac-admin /path/to/env upgrade
     104}}}
     105
     106A 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`.
     107
     108==== Redeploying static resources
     109
     110If 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.
     111
     112Execute the `deploy` command, as is done during install and [TracUpgrade#a5.Refreshstaticresources upgrade]:
     113
     114{{{#!sh
     115$ trac-admin /path/to/env deploy /deploy/path
     116}}}
     117
     118After executing the command, you must restart your web server.
     119
     120{{{#!div style="border: 1pt dotted; margin: 1em"
     121**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.
     122{{{#!comment
     123Remove above note once #9936 is fixed.
     124}}}
     125}}}
     126
     127==== Uninstalling #UninstallWithPip
     128
     129Get a list of installed plugins:
     130{{{#!sh
     131$ pip list
     132Package    Version
     133---------- -------
     134Jinja2     2.10.1
     135MarkupSafe 1.1.1
     136pip        19.2.2
     137setuptools 41.2.0
     138Trac       1.4
     139TracTags   0.10
     140wheel      0.33.6
     141}}}
     142
     143Uninstall a plugin by specifying the package name:
     144{{{#!sh
     145$ pip uninstall TracTags
     146}}}
     147
     148== Web-based plugin administration
     149
     150The admin page offers limited support for plugin configuration to users with `TRAC_ADMIN` permission:
     151
     152* en/dis-abling installed plugins
     153* installing plugins by uploading them as eggs
     154
     155If you wish to disable the second function for security reasons, add the following to your `trac.ini` file:
     156{{{#!ini
     157[components]
     158trac.admin.web_ui.PluginAdminPanel = disabled
     159}}}
     160This disables the whole panel, so the first function will no longer be available.
     161
     162== Setting up the plugin cache
     163
     164Some 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.
     165
     166To do this from the Apache configuration, use the `SetEnv` directive:
     167{{{#!apache
    85168SetEnv PYTHON_EGG_CACHE /path/to/dir
    86169}}}
    87170
    88 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.
    89 
    90 For example (for CGI):
    91 {{{
     171This 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.
     172
     173For example for CGI:
     174{{{#!apache
    92175 <Location /trac>
    93176   SetEnv TRAC_ENV /path/to/projenv
    … …  
    96179}}}
    97180
    98 or (for mod_python):
    99 {{{
     181Or for mod_python:
     182{{{#!apache
    100183 <Location /trac>
    101184   SetHandler mod_python
    … …  
    105188}}}
    106189
    107  ''Note: this requires the `mod_env` module''
    108 
    109 For [wiki:TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
    110 
    111  ''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 atleast one environment variable inside trac.fcgi as expressed in the example on [wiki:TracFastCgi TracFastCgi].
    112 
    113 === About hook scripts ===
    114 
    115 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.
    116 
    117 == Troubleshooting ==
    118 
    119 === Is setuptools properly installed? ===
    120 
    121 Try this from the command line:
    122 {{{
    123 $ python -c "import pkg_resources"
    124 }}}
    125 
    126 If you get '''no output''', setuptools '''is''' installed. Otherwise, you'll need to install it before plugins will work in Trac.
    127 
    128 === Did you get the correct version of the Python egg? ===
    129 
    130 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).
    131 
    132 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.
    133 
    134 === Is the plugin enabled? ===
    135 
    136 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:
    137  * you actually added the necessary line(s) to the `[components]` section
    138  * the package/module names are correct
    139  * the value is “enabled", not e.g. “enable”
    140 
    141 === Check the permissions on the egg file ===
    142 
    143 Trac must be able to read the file.
    144 
    145 === Check the log files ===
    146 
    147 Enable [wiki:TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins.
    148 
    149 === Verify you have proper permissions ===
    150 
    151 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.
    152 
    153 === Is the wrong version of the plugin loading? ===
    154 
    155 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 som basic rules:
    156  * 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.
    157  * 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.
    158  * 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.
    159  * 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.
    160 
    161 === If all of the above failed ===
    162 
    163 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 IrcChannel and ask away.
     190'''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.
     191
     192For [TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
     193
     194'''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:
     195
     196{{{#!apache
     197FastCgiConfig -initial-env TRAC_ENV=/var/lib/trac -initial-env PYTHON_EGG_CACHE=/var/lib/trac/plugin-cache
     198}}}
     199
     200=== About hook scripts
     201
     202If 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.
     203
     204== Writing Trac Plugins
     205
     206You can write your own Trac plugin using the following resources:
     207* [trac:TracDev Developer documentation]
     208* [https://trac-hacks.org Examples on trac-hacks.org]
     209* [trac:browser:branches/1.4-stable/sample-plugins sample-plugins]
     210
     211== Troubleshooting
     212
     213=== Did you get the correct version of the Python egg?
     214
     215Python 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).
     216
     217Also, 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.
     218
     219=== Is the plugin enabled?
     220
     221If 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:
     222
     223 * you added the necessary line(s) to the `[components]` section.
     224 * the package/module names are correct and do not contain typos.
     225 * the value is `enabled`, not `enable` or `Enable`.
     226 * the section name is `components`, not `component`.
     227
     228=== Check the permissions
     229
     230Trac must be able to read the .py file or package (.egg or .whl).
     231
     232=== Check the log files
     233
     234See [trac:TracTroubleshooting#ChecktheLogs].
     235
     236=== Verify you have the proper permissions
     237
     238Some plugins require you have special permissions. !TracTags, for example, requires `TAGS_VIEW` permissions for the //Tags// navigation item to be added.
     239
     240=== Is the wrong version of the plugin loading?
     241
     242If 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:
     243
     244* 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.
     245* 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.
     246* 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.
     247* 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.
     248
     249=== If all of the above failed
     250
     251See TracSupport.
    164252
    165253----
    166 See also TracGuide, [http://trac.edgewall.org/wiki/PluginList plugin list], [http://trac.edgewall.org/wiki/TracDev/ComponentArchitecture component architecture]
     254See also TracGuide, TracIni.