Changes between Version 3 and Version 4 of TracPlugins


Ignore:
Timestamp:
09/03/19 22:57:48 (6 weeks ago)
Author:
trac
Comment:

--

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  • TracPlugins

    v3 v4  
    33= Trac plugins
    44
    5 Trac is extensible with [trac:PluginList plugins]. Plugin functionality is based on the [trac:TracDev/ComponentArchitecture component architecture], with special cases described in the [trac:TracDev/PluginDevelopment plugin development] page.
     5Trac is extensible with [trac:PluginList plugins]. Plugin functionality is based on the [trac:TracDev/ComponentArchitecture component architecture], described in the [trac:TracDev/PluginDevelopment plugin development] page.
    66
    77== Plugin discovery
    88
    9 From the user's point of view, a plugin is either a standalone .py file or 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.
     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.
    1010
    1111== Installing a Trac plugin
    1212
    13 The instructions below are applicable to a plugin packaged as an egg. Plugins implemented as a single `py` file should be downloaded and copied to the [TracEnvironment project environment] `plugins` directory or the [TracIni#GlobalConfiguration global shared] plugins directory.
     13The instructions below are applicable to 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.
    1414
    1515=== For a single project
    1616
    17 If you have downloaded a source distribution of a plugin, and want to build the `.egg` file:
    18 
    19  * Unpack the source. It should provide `setup.py`.
    20  * Run:
     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:
    2124 {{{#!sh
    2225$ python setup.py bdist_egg
    2326}}}
    24 
    25 You should now have an *.egg file. Examine the output of running Python to find where this was created.
    26 
    27 Once 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.
    28 
    29 To uninstall a plugin installed this way, remove the egg from the `plugins` directory and restart the web server.
    30 
    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.
    32 
    33 '''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.
     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.
    3441
    3542=== For all projects
    3643
    37 ==== With an .egg file
    38 
    39 Some plugins, such as [https://trac-hacks.org/wiki/TagsPlugin TracTags], are downloadable as an `.egg` file that can be installed with `easy_install` or `pip`:
    40 {{{#!sh
    41 $ easy_install TracTags
    42 }}}
     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`:
    4355{{{#!sh
    4456$ pip install TracTags
    4557}}}
    4658
    47 If `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 
    51 If Trac reports permission errors after installing a zipped egg, and you would rather not bother providing an egg cache directory writable by the web server, you can get around it by simply unzipping the egg. Just pass `--always-unzip` to `easy_install`:
    52 {{{#!sh
    53 $ easy_install --always-unzip TracTags
    54 }}}
    55 You should end up with a directory having the same name as the zipped egg, complete with `.egg` extension, and containing its uncompressed contents.
    56 
    57 Trac also searches for plugins installed in the shared plugins directory, see TracIni#GlobalConfiguration. This is a convenient way to share the installation of plugins across several, but not all, environments.
     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}}}
    5863
    5964==== From source
    6065
    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 }}}
     66You can install directly from a source repository:
    6567{{{#!sh
    6668$ pip install svn+https://trac-hacks.org/svn/tagsplugin/trunk
    6769}}}
    68 When 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.
     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}}}
    6984
    7085==== Enabling the plugin
    7186
    72 Unlike 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 
    74 This is done in the [TracIni#components-section "[components]"] section of the configuration file `trac.ini`. For example:
     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:
    7590{{{#!ini
    7691[components]
     
    7893}}}
    7994
    80 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`.
     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.
    8198
    8299After installing the plugin, you must restart your web server.
     
    84101==== Upgrading the environment
    85102
    86 Some plugins may require an environment upgrade. This will typically be necessary for plugins that implement `IEnvironmentSetupParticipant`. Common reasons for requiring an environment upgrade are to add tables to the database or add configuration parameters to trac.ini. A notification will be displayed when accessing Trac for the first time after installing a plugin and restarting the web server. To upgrade the environment, run the command:
     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:
    87104
    88105{{{#!sh
     
    96113If 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.
    97114
    98 Execute the `deploy` command, as was done during install and [TracUpgrade#a5.Refreshstaticresources upgrade]:
     115Execute the `deploy` command, as is done during install and [TracUpgrade#a5.Refreshstaticresources upgrade]:
    99116
    100117{{{#!sh
     
    111128}}}
    112129
    113 ==== Upgrading a Plugin
    114 
    115 Normally, upgrading a plugin is simply a matter of repeating the install process. You may want to [#Uninstalling uninstall] old versions of the plugin.
    116 
    117 The `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 
    123 Alternatively 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 
    125130==== Uninstalling
    126131
    127 `pip` makes it easy to uninstall a plugin:
    128 {{{#!sh
    129 $ pip uninstall <pluginname>
    130 }}}
    131 
    132 The `pip uninstall` command can be used even if the plugin was installed using `easy_install` or `python setup.py install`.
    133 
    134 Neither `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 `$PYTHONLIB/site-packages/easy-install.pth` when the plugin is installed by setuptools.
    137  1. Delete executables from `/usr/bin`, `/usr/local/bin`, or `C:\\Python*\Scripts`. To find what executables are involved, refer to the `[console-script]` section of `setup.py`.
    138  1. Delete the .egg file or folder from where it's installed, usually inside `$PYTHONLIB/site-packages/`.
    139  1. Restart the web server.
    140 
    141 If you are uncertain about the location of the egg file, you can try to locate it by replacing `myplugin` with whatever namespace the plugin uses (as used when enabling the plugin):
    142 {{{#!pycon
    143 >>> import myplugin
    144 >>> print myplugin.__file__
    145 /opt/local/python24/lib/site-packages/myplugin-0.4.2-py2.4.egg/myplugin/__init__.pyc
    146 }}}
    147 
    148 == Setting up the plugin cache
    149 
    150 Some 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.
     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}}}
    151150
    152151== Web-based plugin administration
    153152
    154 The !WebAdmin interface offers limited support for plugin configuration to users with `TRAC_ADMIN` permission:
    155 
    156 * enabling and disabling installed plugins
     153The admin page offers limited support for plugin configuration to users with `TRAC_ADMIN` permission:
     154
     155* en/dis-abling installed plugins
    157156* installing plugins by uploading them as eggs
    158157
     
    162161trac.admin.web_ui.PluginAdminPanel = disabled
    163162}}}
    164 This disables the whole panel, so the first function will no longer be available either.
     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
     171SetEnv PYTHON_EGG_CACHE /path/to/dir
     172}}}
     173
     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
     178 <Location /trac>
     179   SetEnv TRAC_ENV /path/to/projenv
     180   SetEnv PYTHON_EGG_CACHE /path/to/dir
     181 </Location>
     182}}}
     183
     184Or for mod_python:
     185{{{#!apache
     186 <Location /trac>
     187   SetHandler mod_python
     188   ...
     189   SetEnv PYTHON_EGG_CACHE /path/to/dir
     190 </Location>
     191}}}
     192
     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
     200FastCgiConfig -initial-env TRAC_ENV=/var/lib/trac -initial-env PYTHON_EGG_CACHE=/var/lib/trac/plugin-cache
     201}}}
     202
     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.
    165206
    166207== Writing Trac Plugins
     
    169210* [trac:TracDev Developer documentation]
    170211* [https://trac-hacks.org Examples on trac-hacks.org]
    171 * [trac:browser:branches/1.2-stable/sample-plugins sample-plugins]
     212* [trac:browser:branches/1.4-stable/sample-plugins sample-plugins]
    172213
    173214== Troubleshooting
    174215
    175 === Is setuptools properly installed?
    176 
    177 Try this from the command line:
    178 {{{#!sh
    179 $ python -c "import pkg_resources"
    180 }}}
    181 
    182 If you get '''no output''', setuptools '''is''' installed. Otherwise, you'll need to install it before plugins will work in Trac.
    183 
    184216=== Did you get the correct version of the Python egg?
    185217
    186218Python 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).
    187219
    188 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.
     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.
    189221
    190222=== Is the plugin enabled?
    191223
    192 If you install a plugin globally, ie ''not'' inside the `plugins` directory of the Trac project environment, you must explicitly enable it in [TracIni trac.ini]. Make sure that:
    193 
    194  * you actually added the necessary line(s) to the `[components]` section.
     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.
    195227 * the package/module names are correct and do not contain typos.
    196  * the value is "enabled", not "enable" or "Enable".
    197  * the section name is "components", not "component".
    198 
    199 === Check the permissions on the .egg file
    200 
    201 Trac must be able to read the .egg file.
     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).
    202234
    203235=== Check the log files
    204236
    205 Enable [TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins.
     237See [trac:TracTroubleshooting#ChecktheLogs].
    206238
    207239=== Verify you have the proper permissions
    208240
    209 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.
     241Some plugins require you have special permissions. !TracTags, for example, requires `TAGS_VIEW` permissions for the //Tags// navigation item to be added.
    210242
    211243=== Is the wrong version of the plugin loading?
    212244
    213 If 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.
     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.
    219251
    220252=== If all of the above failed
    221253
    222 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] or [trac:MailingList] and ask away!
     254See TracSupport.
    223255
    224256----
    225 See also TracGuide, [trac:PluginList plugin list], [trac:TracDev/ComponentArchitecture component architecture].
     257See also TracGuide, TracIni.