Changes between Version 2 and Version 3 of TracPlugins


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Timestamp:
Apr 24, 2017, 10:36:27 AM (8 months ago)
Author:
trac
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  • TracPlugins

    v2 v3  
    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]), or in a local TracEnvironment, in its `plugins` directory.
    9 Except for the later case, the components defined in a plugin 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.
     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.
    1414
    1515To install `setuptools`, download the bootstrap module [http://peak.telecommunity.com/dist/ez_setup.py ez_setup.py] and execute it as follows:
    16 {{{
     16
     17{{{#!sh
    1718$ python ez_setup.py
    1819}}}
    1920
    20 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.
    21 
    22 Plugins can also consist of a single `.py` file dropped into either the environment or the shared plugins directory.
    23 
    24 == Installing a Trac Plugin ==
    25 
    26 === For a Single Project ===
    27 
    28 Plugins are packaged as [http://peak.telecommunity.com/DevCenter/PythonEggs Python eggs]. That means they are ZIP archives with the file extension `.egg`.
    29 
    30 If you have downloaded a source distribution of a plugin, and want to build the `.egg` file, follow this instruction:
    31  * Unpack the source. It should provide a setup.py.
     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`.
    3234 * Run:
    33 {{{
     35 {{{#!sh
    3436$ python setup.py bdist_egg
    3537}}}
    3638
    37 Then you will have a *.egg file. Examine the output of running python to find where this was created.
    38 
    39 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).
    40 
    41 To uninstall a plugin installed this way, remove the egg from `plugins` directory and restart web server.
    42 
    43 Note that the Python version that the egg is built with must
    44 match the Python version with which Trac is run.  If for
    45 instance you are running Trac under Python 2.5, but have
    46 upgraded your standalone Python to 2.6, the eggs won't be
    47 recognized.
    48 
    49 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.
    50 
    51 === For All Projects ===
    52 
    53 ==== With an .egg file ====
    54 
    55 Some plugins (such as [trac:SpamFilter SpamFilter]) are downloadable as a `.egg` file which can be installed with the `easy_install` program:
    56 {{{
    57 easy_install TracSpamFilter
    58 }}}
    59 
    60 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).
    61 
    62 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`:
    63 {{{
    64 easy_install --always-unzip TracSpamFilter-0.4.1_r10106-py2.6.egg
    65 }}}
    66 You should end up with a directory having the same name as the zipped egg (complete with `.egg` extension) and containing its uncompressed contents.
    67 
    68 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.
    69 
    70 ==== From source ====
     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 [trac:SpamFilter SpamFilter], are downloadable as an `.egg` file that can be installed with `easy_install` or `pip`:
     54{{{#!sh
     55$ easy_install TracSpamFilter
     56$ pip install TracSpamFilter
     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 TracSpamFilter-0.4.1_r10106-py2.6.egg
     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
    7172
    7273`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:
    73 {{{
    74 easy_install http://svn.edgewall.com/repos/trac/plugins/0.12/spam-filter-captcha
    75 }}}
    76 
    77 ==== Enabling the plugin ====
    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 shared plugins directory, i.e. 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:
    81 {{{
     74{{{#!sh
     75$ easy_install https://svn.edgewall.org/repos/trac/plugins/1.0/spam-filter
     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
    8284[components]
    8385tracspamfilter.* = enabled
    8486}}}
    8587
    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`.)
    87 
    88 Note: After installing the plugin, you need to restart your web server.
    89 
    90 ==== Uninstalling ====
    91 
    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:
     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
    93106 1. Do `easy_install -m [plugin name]` to remove references from `$PYTHONLIB/site-packages/easy-install.pth` when the plugin installed by setuptools.
    94  1. Delete executables from `/usr/bin`, `/usr/local/bin` or `C:\\Python*\Scripts`. For search what executables are there, you may refer to `[console-script]` section of `setup.py`.
    95  1. Delete the .egg file or folder from where it is installed, usually inside `$PYTHONLIB/site-packages/`.
    96  1. Restart web server.
    97 
    98 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):
    99 {{{
     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
    100113>>> import myplugin
    101114>>> print myplugin.__file__
     
    103116}}}
    104117
    105 == Setting up the Plugin Cache ==
    106 
    107 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.
    108 
    109 To do this from the Apache configuration, use the `SetEnv` directive as follows:
    110 {{{
     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
    111124SetEnv PYTHON_EGG_CACHE /path/to/dir
    112125}}}
    113126
    114 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.
    115 
    116 For example (for CGI):
    117 {{{
     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
    118131 <Location /trac>
    119132   SetEnv TRAC_ENV /path/to/projenv
     
    122135}}}
    123136
    124 or (for mod_python):
    125 {{{
     137Or for mod_python:
     138{{{#!apache
    126139 <Location /trac>
    127140   SetHandler mod_python
     
    131144}}}
    132145
    133  ''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.''
     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.
    134147
    135148For [wiki:TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
    136149
    137  ''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.
    138 
    139 {{{
     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
    140153FastCgiConfig -initial-env TRAC_ENV=/var/lib/trac -initial-env PYTHON_EGG_CACHE=/var/lib/trac/plugin-cache
    141154}}}
    142155
    143 === About hook scripts ===
    144 
    145 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.
    146 
    147 == Troubleshooting ==
    148 
    149 === Is setuptools properly installed? ===
     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?
    150177
    151178Try this from the command line:
    152 {{{
     179{{{#!sh
    153180$ python -c "import pkg_resources"
    154181}}}
     
    156183If you get '''no output''', setuptools '''is''' installed. Otherwise, you'll need to install it before plugins will work in Trac.
    157184
    158 === Did you get the correct version of the Python egg? ===
     185=== Did you get the correct version of the Python egg?
    159186
    160187Python 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).
    161188
    162 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.
    163 
    164 === Is the plugin enabled? ===
    165 
    166 
    167 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:
    168  * you actually added the necessary line(s) to the `[components]` section
    169  * the package/module names are correct
    170  * the value is “enabled", not e.g. “enable”
    171 
    172 === Check the permissions on the egg file ===
    173 
    174 Trac must be able to read the file.
    175 
    176 === Check the log files ===
     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
    177205
    178206Enable [wiki:TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins.
    179207
    180 === Verify you have proper permissions ===
    181 
    182 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.
    183 
    184 === Is the wrong version of the plugin loading? ===
     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?
    185213
    186214If 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:
    187  * 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.
    188  * 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.
    189  * 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.
    190  * 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.
    191 
    192 === If all of the above failed ===
    193 
    194 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.
     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!
    195224
    196225----
    197 See also TracGuide, [trac:PluginList plugin list], [trac:TracDev/ComponentArchitecture component architecture]
     226See also TracGuide, [trac:PluginList plugin list], [trac:TracDev/ComponentArchitecture component architecture].