Changes between Version 3 and Version 4 of TracPlugins


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Timestamp:
Dec 4, 2020, 2:27:59 PM (4 years ago)
Author:
trac
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  • TracPlugins

    v3 v4  
    1 = Trac Plugins =
    2 [[TracGuideToc]]
    3 
    4 Trac is extensible with [trac:PluginList plugins] since version 0.9. The plugin functionality is based on the [trac:TracDev/ComponentArchitecture component architecture] with peculiarities described at [TracDev/PluginDevelopment plugin development] page.
    5 
    6 == Plugin discovery ==
    7 
    8 From the user point of view a Plugin is either standalone .py file or an .egg package. Trac looks for Plugins in a global shared plugins directory (see [TracIni#GlobalConfiguration Global Configuration]) and in `plugins` directory of local TracEnvironment. Components defined in globally installed plugins should be explicitly enabled in the [[TracIni#components-section| [components] ]] section of the trac.ini file.
    9 
    10 == Requirements for Trac eggs  ==
    11 
    12 To use egg based plugins in Trac, you need to have [http://peak.telecommunity.com/DevCenter/setuptools setuptools] (version 0.6) installed.
    13 
    14 To install `setuptools`, download the bootstrap module [http://peak.telecommunity.com/dist/ez_setup.py ez_setup.py] and execute it as follows:
    15 {{{
    16 $ python ez_setup.py
    17 }}}
    18 
    19 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.
    20 
    21 Plugins can also consist of a single `.py` file dropped directly into the root of environment's or into shared `plugins` directory.
    22 
    23 == Installing a Trac Plugin ==
    24 
    25 === For a Single Project ===
    26 
    27 Plugins are packaged as [http://peak.telecommunity.com/DevCenter/PythonEggs Python eggs]. That means they are ZIP archives with the file extension `.egg`.
    28 
    29 If you have downloaded a source distribution of a plugin, and want to build the `.egg` file, follow this instruction:
    30  * Unpack the source. It should provide a setup.py.
    31  * Run:
    32 {{{
     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
     9From the user's point of view, a 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
     18format, as the wheel format (described below) is not
     19supported by the setuptools loading mechanism. Build the `egg` file from the plugin source:
     20
     21* Checkout or download and unpack the source.
     22* Change to the directory containing `setup.py`.
     23* Run:
     24 {{{#!sh
    3325$ python setup.py bdist_egg
    3426}}}
    35 
    36 Then you will have a *.egg file. Examine the output of running python to find where this was created.
    37 
    38 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. Then, restart the web server (this requirement was not previously mentioned in this document, but in my tests it began working only after I did so).
    39 
    40 To uninstall a plugin installed this way, remove the egg from `plugins` directory and restart web server.
    41 
    42 Note that the Python version that the egg is built with must
    43 match the Python version with which Trac is run.  If for
    44 instance you are running Trac under Python 2.5, but have
    45 upgraded your standalone Python to 2.6, the eggs won't be
    46 recognized.
    47 
    48 Note also that in a multi-project setup, a pool of Python interpreter instances will be dynamically allocated to projects based on need, and 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 the 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.
    49 
    50 === For All Projects ===
    51 
    52 ==== With an .egg file ====
    53 
    54 Some plugins (such as [trac:SpamFilter SpamFilter]) are downloadable as a `.egg` file which can be installed with the `easy_install` program:
    55 {{{
    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 {{{
    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.
    66 
    67 Trac also searches for plugins installed in the shared plugins directory ''(since 0.10)'', see TracIni#GlobalConfiguration. This is a convenient way to share the installation of plugins across several but not all environments.
    68 
    69 ==== From source ====
    70 
    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 {{{
    73 easy_install http://svn.edgewall.com/repos/trac/plugins/0.12/spam-filter-captcha
    74 }}}
    75 
    76 ==== Enabling the plugin ====
    77 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 shared plugins directory, i.e. the path specified in the `[inherit] plugins_dir` configuration option.
    78 
    79 This is done in the `[components]` section of the configuration file, for example:
    80 {{{
     27 The egg file will be created in the `dist` subdirectory.
     28* Copy the egg file to the `plugins` directory of the [TracEnvironment project environment].
     29
     30Make 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).
     31
     32Trac 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.
     33
     34'''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.
     35
     36'''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.
     37
     38==== Uninstalling
     39
     40Remove the egg from the `plugins` directory and restart the web server.
     41
     42=== For all projects
     43
     44==== Using pip
     45
     46The 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].
     47
     48Using `pip`, the plugin will be installed
     49in the [https://pythonwheels.com/ wheel format], which is the modern standard for Python and a
     50replacement for the egg format.
     51
     52==== From PyPI
     53
     54Some plugins, such as [th:TagsPlugin TracTags], can be installed directly from [https://pypi.org PyPI] using `pip`:
     55{{{#!sh
     56$ pip install TracTags
     57}}}
     58
     59The version can be specified, which can be useful if you don't want to install the latest:
     60{{{#!sh
     61$ pip install TracTags==0.10
     62}}}
     63
     64==== From source
     65
     66You can install directly from a source repository:
     67{{{#!sh
     68$ pip install svn+https://trac-hacks.org/svn/tagsplugin/trunk
     69}}}
     70
     71Replace the `svn+` prefix with `git+` if installing
     72from a Git repository.
     73
     74Or from the path or URL of a tar.gz or zip archive:
     75{{{#!sh
     76$ pip install https://trac-hacks.org/browser/tagsplugin/trunk?format=zip
     77}}}
     78
     79Or checkout the source and provide `pip` a path to the source directory:
     80{{{#!sh
     81$ svn co https://trac-hacks.org/svn/tagsplugin/trunk tractags
     82$ pip install tractags
     83}}}
     84
     85==== Enabling the plugin
     86
     87Unlike plugins installed per environment, you have to explicitly enable globally installed plugins. This also applies to plugins installed in the shared plugins directory.
     88
     89This is done in the `[components]` section of the configuration file `trac.ini`. For example:
     90{{{#!ini
    8191[components]
    82 tracspamfilter.* = enabled
    83 }}}
    84 
    85 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`.)
    86 
    87 Note: After installing the plugin, you need to restart your web server.
    88 
    89 ==== Uninstalling ====
    90 
    91 `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:
    92  1. Do `easy_install -m [plugin name]` to remove references from `$PYTHONLIB/site-packages/easy-install.pth` when the plugin installed by setuptools.
    93  1. Delete executables from `/usr/bin`, `/usr/local/bin` or `C:\\Python*\Scripts`. For search what executables are there, you may refer to `[console-script]` section of `setup.py`.
    94  1. Delete the .egg file or folder from where it is installed, usually inside `$PYTHONLIB/site-packages/`.
    95  1. Restart web server.
    96 
    97 If you are uncertain about the location of the egg, here is a small tip to help locate an egg (or any package) - replace `myplugin` with whatever namespace the plugin uses (as used when enabling the plugin):
    98 {{{
    99 >>> import myplugin
    100 >>> print myplugin.__file__
    101 /opt/local/python24/lib/site-packages/myplugin-0.4.2-py2.4.egg/myplugin/__init__.pyc
    102 }}}
    103 
    104 == Setting up the Plugin Cache ==
    105 
    106 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.
    107 
    108 To do this from the Apache configuration, use the `SetEnv` directive as follows:
    109 {{{
     92tractags.* = enabled
     93}}}
     94
     95The 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`.
     96
     97Plugins can also be enabled from the [#Web-basedpluginadministration administration] page.
     98
     99After installing the plugin, you must restart your web server.
     100
     101==== Upgrading the environment
     102
     103Some 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:
     104
     105{{{#!sh
     106$ trac-admin /path/to/env upgrade
     107}}}
     108
     109A 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`.
     110
     111==== Redeploying static resources
     112
     113If 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.
     114
     115Execute the `deploy` command, as is done during install and [TracUpgrade#a5.Refreshstaticresources upgrade]:
     116
     117{{{#!sh
     118$ trac-admin /path/to/env deploy /deploy/path
     119}}}
     120
     121After executing the command, you must restart your web server.
     122
     123{{{#!div style="border: 1pt dotted; margin: 1em"
     124**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.
     125{{{#!comment
     126Remove above note once #9936 is fixed.
     127}}}
     128}}}
     129
     130==== Uninstalling
     131
     132Get a list of installed plugins:
     133{{{#!sh
     134$ pip list
     135Package    Version
     136---------- -------
     137Jinja2     2.10.1
     138MarkupSafe 1.1.1
     139pip        19.2.2
     140setuptools 41.2.0
     141Trac       1.4
     142TracTags   0.10
     143wheel      0.33.6
     144}}}
     145
     146Uninstall a plugin by specifying the package name:
     147{{{#!sh
     148$ pip uninstall TracTags
     149}}}
     150
     151== Web-based plugin administration
     152
     153The admin page offers limited support for plugin configuration to users with `TRAC_ADMIN` permission:
     154
     155* en/dis-abling installed plugins
     156* installing plugins by uploading them as eggs
     157
     158If you wish to disable the second function for security reasons, add the following to your `trac.ini` file:
     159{{{#!ini
     160[components]
     161trac.admin.web_ui.PluginAdminPanel = disabled
     162}}}
     163This disables the whole panel, so the first function will no longer be available.
     164
     165== Setting up the plugin cache
     166
     167Some 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.
     168
     169To do this from the Apache configuration, use the `SetEnv` directive:
     170{{{#!apache
    110171SetEnv PYTHON_EGG_CACHE /path/to/dir
    111172}}}
    112173
    113 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.
    114 
    115 For example (for CGI):
    116 {{{
     174This 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.
     175
     176For example for CGI:
     177{{{#!apache
    117178 <Location /trac>
    118179   SetEnv TRAC_ENV /path/to/projenv
    … …  
    121182}}}
    122183
    123 or (for mod_python):
    124 {{{
     184Or for mod_python:
     185{{{#!apache
    125186 <Location /trac>
    126187   SetHandler mod_python
    … …  
    130191}}}
    131192
    132  ''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.''
    133 
    134 For [wiki:TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
    135 
    136  ''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. I.e.
    137 
    138 {{{
     193'''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.
     194
     195For [TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
     196
     197'''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:
     198
     199{{{#!apache
    139200FastCgiConfig -initial-env TRAC_ENV=/var/lib/trac -initial-env PYTHON_EGG_CACHE=/var/lib/trac/plugin-cache
    140201}}}
    141202
    142 === About hook scripts ===
    143 
    144 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.
    145 
    146 == Troubleshooting ==
    147 
    148 === Is setuptools properly installed? ===
    149 
    150 Try this from the command line:
    151 {{{
    152 $ python -c "import pkg_resources"
    153 }}}
    154 
    155 If you get '''no output''', setuptools '''is''' installed. Otherwise, you'll need to install it before plugins will work in Trac.
    156 
    157 === Did you get the correct version of the Python egg? ===
     203=== About hook scripts
     204
     205If 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.
     206
     207== Writing Trac Plugins
     208
     209You can write your own Trac plugin using the following resources:
     210* [trac:TracDev Developer documentation]
     211* [https://trac-hacks.org Examples on trac-hacks.org]
     212* [trac:browser:branches/1.4-stable/sample-plugins sample-plugins]
     213
     214== Troubleshooting
     215
     216=== Did you get the correct version of the Python egg?
    158217
    159218Python 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).
    160219
    161 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.
    162 
    163 === Is the plugin enabled? ===
    164 
    165 
    166 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:
    167  * you actually added the necessary line(s) to the `[components]` section
    168  * the package/module names are correct
    169  * the value is “enabled", not e.g. “enable”
    170 
    171 === Check the permissions on the egg file ===
    172 
    173 Trac must be able to read the file.
    174 
    175 === Check the log files ===
    176 
    177 Enable [wiki:TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins.
    178 
    179 === Verify you have proper permissions ===
    180 
    181 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.
    182 
    183 === Is the wrong version of the plugin loading? ===
    184 
    185 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:
    186  * 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.
    187  * 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.
    188  * 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.
    189  * 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.
    190 
    191 === If all of the above failed ===
    192 
    193 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 [trac:IrcChannel IrcChannel] and ask away.
     220Also, 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.
     221
     222=== Is the plugin enabled?
     223
     224If 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:
     225
     226 * you added the necessary line(s) to the `[components]` section.
     227 * the package/module names are correct and do not contain typos.
     228 * the value is `enabled`, not `enable` or `Enable`.
     229 * the section name is `components`, not `component`.
     230
     231=== Check the permissions
     232
     233Trac must be able to read the .py file or package (.egg or .whl).
     234
     235=== Check the log files
     236
     237See [trac:TracTroubleshooting#ChecktheLogs].
     238
     239=== Verify you have the proper permissions
     240
     241Some plugins require you have special permissions. !TracTags, for example, requires `TAGS_VIEW` permissions for the //Tags// navigation item to be added.
     242
     243=== Is the wrong version of the plugin loading?
     244
     245If 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:
     246
     247* 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.
     248* 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.
     249* 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.
     250* 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.
     251
     252=== If all of the above failed
     253
     254See TracSupport.
    194255
    195256----
    196 See also TracGuide, [trac:PluginList plugin list], [trac:TracDev/ComponentArchitecture component architecture]
     257See also TracGuide, TracIni.