Changes between Version 1 and Version 2 of TracPlugins


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Timestamp:
Feb 13, 2021 12:24:55 AM (4 years ago)
Author:
trac
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  • TracPlugins

    v1 v2  
    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 Plugins can also consist of a single `.py` file dropped into either the environment or global `plugins` directory ''(since [milestone:0.10])''.
     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], with special cases described in the [trac:TracDev/PluginDevelopment plugin development] page.
     6
     7== Plugin discovery
     8
     9From 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
     13To use egg-based plugins in Trac, you need to have [http://peak.telecommunity.com/DevCenter/setuptools setuptools] (version >= 0.6) installed.
    1114
    1215To install `setuptools`, download the bootstrap module [http://peak.telecommunity.com/dist/ez_setup.py ez_setup.py] and execute it as follows:
    13 {{{
     16
     17{{{#!sh
    1418$ python ez_setup.py
    1519}}}
    1620
    17 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.
    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`. If you have downloaded a source distribution of a plugin, you can run:
    24 {{{
     21If the `ez_setup.py` script fails to install the setuptools release, you can download it from [pypi:setuptools PyPI] and install it manually.
     22
     23Plugins can also consist of a single `.py` file dropped directly into either the project's or the shared `plugins` directory.
     24
     25== Installing a Trac plugin
     26
     27The 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.
     28
     29=== For a single project
     30
     31If 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:
     35 {{{#!sh
    2536$ python setup.py bdist_egg
    2637}}}
    27 to build the `.egg` file.
    28 
    29 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.
    30 
    31 Note that the Python version that the egg is built with must
    32 match the Python version with which Trac is run.  If for
    33 instance you are running Trac under Python 2.3, but have
    34 upgraded your standalone Python to 2.4, the eggs won't be
    35 recognized.
    36 
    37 === For All Projects ===
    38 
    39 ==== With an .egg file ====
    40 
    41 Some plugins (such as [http://trac.edgewall.org/wiki/WebAdmin WebAdmin]) are downloadable as a `.egg` file which can be installed with the `easy_install` program:
    42 {{{
    43 easy_install TracWebAdmin-0.1.1dev_r2765-py2.3.egg
    44 }}}
    45 
    46 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).
    47 
    48 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`:
    49 {{{
    50 easy_install --always-unzip TracWebAdmin-0.1.1dev_r2765-py2.3.egg
    51 }}}
    52 You should end up with a directory having the same name as the zipped egg (complete with `.egg` extension) and containing its uncompressed contents.
    53 
    54 Trac also searches for globally installed plugins under `$prefix/share/trac/plugins` ''(since 0.10)''.
    55 
    56 ==== From source ====
    57 
    58 If you downloaded the plugin's source from Subversion, or a source zip file you can install it using the included `setup.py`:
    59 {{{
    60 $ python setup.py install
    61 }}}
    62 
    63 ==== Enabling the plugin ====
    64 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:
    65 {{{
     38
     39You should now have an *.egg file. Examine the output of running Python to find where this was created.
     40
     41Once you have the plugin archive, copy it into the `plugins` directory of the [wiki:TracEnvironment project environment]. Also, make sure that the web server has sufficient permissions to read the plugin egg. Then restart the web server. If you are running as a [wiki:TracStandalone "tracd" standalone server], restart tracd, ie kill the process and run again.
     42
     43To 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.
     48
     49=== For all projects
     50
     51==== With an .egg file
     52
     53Some 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
     56$ pip install TracTags
     57}}}
     58
     59If `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
     63If 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}}}
     67You should end up with a directory having the same name as the zipped egg, complete with `.egg` extension, and containing its uncompressed contents.
     68
     69Trac 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.
     70
     71==== From source
     72
     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
     76}}}
     77
     78==== Enabling the plugin
     79
     80Unlike 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.
     81
     82This is done in the `[components]` section of the configuration file `trac.ini`. For example:
     83{{{#!ini
    6684[components]
    67 webadmin.* = enabled
    68 }}}
    69 
    70 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 find out by looking at the source (look for a top-level directory that contains a file named `__init__.py`.)
    71 
    72 Note: After installing the plugin, you may need to restart Apache.
    73 
    74 == Setting up the Plugin Cache ==
    75 
    76 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.
    77 
    78 To do this from the Apache configuration, use the `SetEnv` directive as follows:
    79 {{{
     85tractags.* = enabled
     86}}}
     87
     88The 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`.
     89
     90After installing the plugin, you must restart your web server.
     91
     92==== Upgrading the environment
     93
     94Some 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:
     95
     96{{{#!sh
     97$ trac-admin /path/to/env upgrade
     98}}}
     99
     100A 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`.
     101
     102==== Uninstalling
     103
     104Neither `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
     111If 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}}}
     117
     118== Setting up the plugin cache
     119
     120Some 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.
     121
     122To do this from the Apache configuration, use the `SetEnv` directive:
     123{{{#!apache
    80124SetEnv PYTHON_EGG_CACHE /path/to/dir
    81125}}}
    82126
    83 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.
    84 
    85 For example (for CGI):
    86 {{{
     127This 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.
     128
     129For example for CGI:
     130{{{#!apache
    87131 <Location /trac>
    88132   SetEnv TRAC_ENV /path/to/projenv
    … …  
    91135}}}
    92136
    93 or (for mod_python):
    94 {{{
     137Or for mod_python:
     138{{{#!apache
    95139 <Location /trac>
    96140   SetHandler mod_python
    … …  
    100144}}}
    101145
    102  ''Note: this requires the `mod_env` module''
    103 
    104 For [wiki:TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
    105 
    106 === About hook scripts ===
    107 
    108 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.
    109 
    110 == Troubleshooting ==
    111 
    112 === Is setuptools properly installed? ===
     146'''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.
     147
     148For [wiki:TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
     149
     150'''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:
     151
     152{{{#!apache
     153FastCgiConfig -initial-env TRAC_ENV=/var/lib/trac -initial-env PYTHON_EGG_CACHE=/var/lib/trac/plugin-cache
     154}}}
     155
     156=== About hook scripts
     157
     158If 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
     162The [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
     167If you wish to disable the second function for security reasons, add the following to your `trac.ini` file:
     168{{{#!ini
     169[components]
     170trac.admin.web_ui.PluginAdminPanel = disabled
     171}}}
     172This disables the whole panel, so the first function will no longer be available either.
     173
     174== Troubleshooting
     175
     176=== Is setuptools properly installed?
    113177
    114178Try this from the command line:
    115 {{{
     179{{{#!sh
    116180$ python -c "import pkg_resources"
    117181}}}
    … …  
    119183If you get '''no output''', setuptools '''is''' installed. Otherwise, you'll need to install it before plugins will work in Trac.
    120184
    121 === Did you get the correct version of the Python egg? ===
    122 
    123 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).
    124 
    125 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.
    126 
    127 === Is the plugin enabled? ===
    128 
    129 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:
    130  * you actually added the necessary line(s) to the `[components]` section
    131  * the package/module names are correct
    132  * if you're reference a module (as opposed to a class), you've appended the necessary “.*”
    133  * the value is “enabled", not e.g. “enable”
    134 
    135 === Check the permissions on the egg file ===
    136 
    137 Trac must of course be able to read the file. Yeah, you knew that ;-)
    138 
    139 === Check the log files ===
    140 
    141 Enable [TracLogging logging] in Trac, set the log level to `DEBUG` and then watch the log file for messages about loading plugins.
     185=== Did you get the correct version of the Python egg?
     186
     187Python 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
     189Also, 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.
     190
     191=== Is the plugin enabled?
     192
     193If 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.
     196 * 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
     202Trac must be able to read the .egg file.
     203
     204=== Check the log files
     205
     206Enable [wiki:TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins.
     207
     208=== Verify you have the proper permissions
     209
     210Some 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.
     211
     212=== Is the wrong version of the plugin loading?
     213
     214If 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.
     220
     221=== If all of the above failed
     222
     223Okay, 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!
    142224
    143225----
    144 See also TracGuide, [http://trac.edgewall.org/wiki/PluginList plugin list], [http://trac.edgewall.org/wiki/TracDev/ComponentArchitecture component architecture]
     226See also TracGuide, [trac:PluginList plugin list], [trac:TracDev/ComponentArchitecture component architecture].