Changes between Version 3 and Version 4 of TracPlugins


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Timestamp:
Apr 21, 2021 12:46:18 PM (4 years ago)
Author:
trac
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  • TracPlugins

    v3 v4  
     1[[PageOutline(2-5,Contents,pullout)]]
     2
    13= Trac plugins
    24
    3 [[TracGuideToc]]
    4 
    5 Trac is extensible with [trac:PluginList plugins]. Plugin functionality is based on the [trac:TracDev/ComponentArchitecture component architecture], with peculiarities 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], with special cases 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 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.
    10 
    11 == Requirements for Trac eggs
    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 [http://www.python.org/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.
     9From 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.
    2410
    2511== Installing a Trac plugin
    2612
     13The 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.
     14
    2715=== For a single project
    28 
    29 Plugins are typically packaged as [http://peak.telecommunity.com/DevCenter/PythonEggs Python eggs]. That means they are .zip archives with the file extension `.egg`.
    3016
    3117If you have downloaded a source distribution of a plugin, and want to build the `.egg` file:
    … …  
    3319 * Unpack the source. It should provide `setup.py`.
    3420 * Run:
    35 
    36 {{{#!sh
     21 {{{#!sh
    3722$ python setup.py bdist_egg
    3823}}}
    3924
    40 You should have a *.egg file. Examine the output of running Python to find where this was created.
    41 
    42 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 (kill and run again).
     25You should now have an *.egg file. Examine the output of running Python to find where this was created.
     26
     27Once 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.
    4328
    4429To uninstall a plugin installed this way, remove the egg from the `plugins` directory and restart the web server.
    4530
    46 '''Note''': 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.
     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.
    4732
    4833'''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.
    … …  
    5237==== With an .egg file
    5338
    54 Some plugins, such as [trac:SpamFilter SpamFilter], are downloadable as an `.egg` file that can be installed with `easy_install`:
    55 {{{#!sh
    56 $ easy_install TracSpamFilter
    57 }}}
    58 
    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`:
    62 {{{#!sh
    63 $ easy_install --always-unzip TracSpamFilter-0.4.1_r10106-py2.6.egg
    64 }}}
    65 You should end up with a directory having the same name as the zipped egg (complete with `.egg` extension) and containing its uncompressed contents.
     39Some 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}}}
     43{{{#!sh
     44$ pip install TracTags
     45}}}
     46
     47If `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
     51If 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}}}
     55You should end up with a directory having the same name as the zipped egg, complete with `.egg` extension, and containing its uncompressed contents.
    6656
    6757Trac 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.
    … …  
    6959==== From source
    7060
    71 `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:
    72 {{{#!sh
    73 $ easy_install http://svn.edgewall.com/repos/trac/plugins/0.12/spam-filter-captcha
    74 }}}
     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}}}
     65{{{#!sh
     66$ pip install svn+https://trac-hacks.org/svn/tagsplugin/trunk
     67}}}
     68When 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.
    7569
    7670==== Enabling the plugin
    7771
    78 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.
    79 
    80 This is done in the `[components]` section of the configuration file. For example:
     72Unlike 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
     74This is done in the [TracIni#components-section "[components]"] section of the configuration file `trac.ini`. For example:
    8175{{{#!ini
    8276[components]
    83 tracspamfilter.* = enabled
    84 }}}
    85 
    86 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`).
     77tractags.* = enabled
     78}}}
     79
     80The 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`.
    8781
    8882After installing the plugin, you must restart your web server.
    8983
     84==== Upgrading the environment
     85
     86Some 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:
     87
     88{{{#!sh
     89$ trac-admin /path/to/env upgrade
     90}}}
     91
     92A 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`.
     93
     94==== Redeploying static resources
     95
     96If 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
     98Execute the `deploy` command, as was done during install and [TracUpgrade#a5.Refreshstaticresources upgrade]:
     99
     100{{{#!sh
     101$ trac-admin /path/to/env deploy /deploy/path
     102}}}
     103
     104After executing the command, you must restart your web server.
     105
     106{{{#!div style="border: 1pt dotted; margin: 1em"
     107**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.
     108{{{#!comment
     109Remove above note once #9936 is fixed.
     110}}}
     111}}}
     112
     113==== Upgrading a Plugin
     114
     115Normally, upgrading a plugin is simply a matter of repeating the install process. You may want to [#Uninstalling uninstall] old versions of the plugin.
     116
     117The `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
     123Alternatively 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
    90125==== Uninstalling
    91126
    92 `easy_install` or `python setup.py` does not have an uninstall feature. Hower, it is usually quite trivial to remove a globally-installed egg and reference:
    93 
    94  1. Do `easy_install -m [plugin name]` to remove references from `$PYTHONLIB/site-packages/easy-install.pth` when the plugin installed by setuptools.
     127`pip` makes it easy to uninstall a plugin:
     128{{{#!sh
     129$ pip uninstall <pluginname>
     130}}}
     131
     132The `pip uninstall` command can be used even if the plugin was installed using `easy_install` or `python setup.py install`.
     133
     134Neither `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 `$PYTHONLIB/site-packages/easy-install.pth` when the plugin is installed by setuptools.
    95137 1. Delete executables from `/usr/bin`, `/usr/local/bin`, or `C:\\Python*\Scripts`. To find what executables are involved, refer to the `[console-script]` section of `setup.py`.
    96  1. Delete the .egg file or folder from where it's installed (usually inside `$PYTHONLIB/site-packages/`).
     138 1. Delete the .egg file or folder from where it's installed, usually inside `$PYTHONLIB/site-packages/`.
    97139 1. Restart the web server.
    98140
    99 If 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):
     141If 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):
    100142{{{#!pycon
    101143>>> import myplugin
    … …  
    106148== Setting up the plugin cache
    107149
    108 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.
    109 
    110 To do this from the Apache configuration, use the `SetEnv` directive:
    111 {{{#!apache
    112 SetEnv PYTHON_EGG_CACHE /path/to/dir
    113 }}}
    114 
    115 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.
    116 
    117 For example (for CGI):
    118 {{{#!apache
    119  <Location /trac>
    120    SetEnv TRAC_ENV /path/to/projenv
    121    SetEnv PYTHON_EGG_CACHE /path/to/dir
    122  </Location>
    123 }}}
    124 
    125 Or (for mod_python):
    126 {{{#!apache
    127  <Location /trac>
    128    SetHandler mod_python
    129    ...
    130    SetEnv PYTHON_EGG_CACHE /path/to/dir
    131  </Location>
    132 }}}
    133 
    134 '''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.
    135 
    136 For [wiki:TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
    137 
    138 '''Note''': that if you already use -initial-env to set the project directory for either a single project or parent you will need to add an additional -initial-env directive to the !FastCgiConfig directive:
    139 
    140 {{{#!apache
    141 FastCgiConfig -initial-env TRAC_ENV=/var/lib/trac -initial-env PYTHON_EGG_CACHE=/var/lib/trac/plugin-cache
    142 }}}
    143 
    144 === About hook scripts
    145 
    146 If 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.
     150Some 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.
     151
     152== Web-based plugin administration
     153
     154The !WebAdmin interface offers limited support for plugin configuration to users with `TRAC_ADMIN` permission:
     155
     156* enabling and disabling installed plugins
     157* installing plugins by uploading them as eggs
     158
     159If you wish to disable the second function for security reasons, add the following to your `trac.ini` file:
     160{{{#!ini
     161[components]
     162trac.admin.web_ui.PluginAdminPanel = disabled
     163}}}
     164This disables the whole panel, so the first function will no longer be available either.
     165
     166== Writing Trac Plugins
     167
     168You can write your own Trac plugin using the following resources:
     169* [trac:TracDev Developer documentation]
     170* [https://trac-hacks.org Examples on trac-hacks.org]
     171* [trac:browser:branches/1.2-stable/sample-plugins sample-plugins]
    147172
    148173== Troubleshooting
    … …  
    168193
    169194 * you actually added the necessary line(s) to the `[components]` section.
    170  * the package/module names are correct.
     195 * the package/module names are correct and do not contain typos.
    171196 * the value is "enabled", not "enable" or "Enable".
    172197 * the section name is "components", not "component".
    … …  
    178203=== Check the log files
    179204
    180 Enable [wiki:TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins.
    181 
    182 === Verify you have proper permissions
    183 
    184 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.
     205Enable [TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins.
     206
     207=== Verify you have the proper permissions
     208
     209Some 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.
    185210
    186211=== Is the wrong version of the plugin loading?
    187212
    188 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:
    189 
    190  * 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.
    191  * 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.
    192  * 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.
    193  * 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.
     213If 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:
     214
     215 * 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.
     216 * 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.
     217 * 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.
     218 * 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.
    194219
    195220=== If all of the above failed
    196221
    197 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!
    198 
    199 == Web-based plugin administration
    200 
    201 The [trac:WebAdmin] interface offers limited support for plugin configuration through the web to users with `TRAC_ADMIN` permission:
    202 
    203 * en/disabling installed plugins
    204 * installing plugins by uploading them as eggs
    205 
    206 If you wish to disable the second function for security reasons, add the following to the `[components]` section of trac.ini:
    207 {{{#!ini
    208 trac.admin.web_ui.PluginAdminPanel = disabled
    209 }}}
    210 This disables the whole panel, so the first function will no longer be available either.
     222Okay, 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!
    211223
    212224----