Changes between Version 2 and Version 3 of TracPlugins


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Timestamp:
Apr 20, 2015 8:51:57 PM (10 years ago)
Author:
trac
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  • TracPlugins

    v2 v3  
    1 = Trac Plugins =
     1= Trac plugins
     2
    23[[TracGuideToc]]
    34
    4 Since version 0.9, Trac supports [trac:PluginList plugins] that extend the built-in functionality. The plugin functionality is based on the [trac:TracDev/ComponentArchitecture component architecture].
    5 
    6 Plugins can be either installed globally, in a shared plugins directory  (see [TracIni#GlobalConfiguration Global Configuration]) or locally for specific TracEnvironment, in its `plugins` directory.
    7 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.
    8 
    9 == Requirements ==
    10 
    11 To use egg based plugins in Trac, you need to have [http://peak.telecommunity.com/DevCenter/setuptools setuptools] (version 0.6) installed.
     5Trac is extensible with [trac:PluginList plugins]. Plugin functionality is based on the [trac:TracDev/ComponentArchitecture component architecture], with peculiarities described in the [trac:TracDev/PluginDevelopment plugin development] page.
     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 the global shared plugins directory (see [TracIni#GlobalConfiguration Global Configuration]) and in the `plugins` directory of the local TracEnvironment. Components defined in globally-installed plugins should be explicitly enabled in the [[TracIni#components-section| [components] ]] section of the trac.ini file.
     10
     11== Requirements for Trac eggs
     12
     13To use egg-based plugins in Trac, you need to have [http://peak.telecommunity.com/DevCenter/setuptools setuptools] (version 0.6) installed.
    1214
    1315To install `setuptools`, download the bootstrap module [http://peak.telecommunity.com/dist/ez_setup.py ez_setup.py] and execute it as follows:
    14 {{{
     16
     17{{{#!sh
    1518$ python ez_setup.py
    1619}}}
    … …  
    1821If 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.
    1922
    20 Plugins can also consist of a single `.py` file dropped into either the environment or the shared plugins directory.
    21 
    22 == Installing a Trac Plugin ==
    23 
    24 === For a Single Project ===
    25 
    26 Plugins are packaged as [http://peak.telecommunity.com/DevCenter/PythonEggs Python eggs]. That means they are ZIP archives with the file extension `.egg`.
    27 
    28 If you have downloaded a source distribution of a plugin, and want to build the `.egg` file, follow this instruction:
    29  * Unpack the source. It should provide a setup.py.
     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
     27=== For a single project
     28
     29Plugins are typically packaged as [http://peak.telecommunity.com/DevCenter/PythonEggs Python eggs]. That means they are .zip archives with the file extension `.egg`.
     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`.
    3034 * Run:
    31 {{{
     35
     36{{{#!sh
    3237$ python setup.py bdist_egg
    3338}}}
    3439
    35 Then you will have a *.egg file. Examine the output of running python to find where this was created.
    36 
    37 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).
    38 
    39 To uninstall a plugin installed this way, remove the egg from `plugins` directory and restart web server.
    40 
    41 Note that the Python version that the egg is built with must
    42 match the Python version with which Trac is run.  If for
    43 instance you are running Trac under Python 2.5, but have
    44 upgraded your standalone Python to 2.6, the eggs won't be
    45 recognized.
    46 
    47 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.
    48 
    49 === For All Projects ===
    50 
    51 ==== With an .egg file ====
    52 
    53 Some plugins (such as [trac:SpamFilter SpamFilter]) are downloadable as a `.egg` file which can be installed with the `easy_install` program:
    54 {{{
    55 easy_install TracSpamFilter
    56 }}}
    57 
    58 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).
    59 
    60 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`:
    61 {{{
    62 easy_install --always-unzip TracSpamFilter-0.2.1dev_r5943-py2.4.egg
     40You should have a *.egg file. Examine the output of running Python to find where this was created.
     41
     42Once you have the plugin archive, copy it into the `plugins` directory of the [wiki:TracEnvironment project environment]. Also, make sure that the web server has sufficient permissions to read the plugin egg. Then restart the web server. If you are running as a [wiki:TracStandalone "tracd" standalone server], restart tracd (kill and run again).
     43
     44To uninstall a plugin installed this way, remove the egg from the `plugins` directory and restart the web server.
     45
     46'''Note''': the Python version that the egg is built with ''must'' match the Python version with which Trac is run. For example, if you're running Trac under Python 2.5, but have upgraded your standalone Python to 2.6, the eggs won't be recognized.
     47
     48'''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.
     49
     50=== For all projects
     51
     52==== With an .egg file
     53
     54Some plugins, such as [trac:SpamFilter SpamFilter], are downloadable as an `.egg` file that can be installed with `easy_install`:
     55{{{#!sh
     56$ easy_install TracSpamFilter
     57}}}
     58
     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:\Python24\Scripts`) to their `PATH` environment variable. See [http://peak.telecommunity.com/DevCenter/EasyInstall#windows-notes easy_install Windows notes] for more information.
     60
     61If Trac reports permission errors after installing a zipped egg, and you would rather not bother providing a egg cache directory writable by the web server, you can get around it by simply unzipping the egg. Just pass `--always-unzip` to `easy_install`:
     62{{{#!sh
     63$ easy_install --always-unzip TracSpamFilter-0.4.1_r10106-py2.6.egg
    6364}}}
    6465You should end up with a directory having the same name as the zipped egg (complete with `.egg` extension) and containing its uncompressed contents.
    6566
    66 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.
    67 
    68 ==== From source ====
     67Trac 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.
     68
     69==== From source
    6970
    7071`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:
    71 {{{
    72 easy_install http://svn.edgewall.com/repos/trac/plugins/0.11/spam-filter
    73 }}}
    74 
    75 ==== Enabling the plugin ====
    76 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.
    77 
    78 This is done in the `[components]` section of the configuration file, for example:
    79 {{{
     72{{{#!sh
     73$ easy_install http://svn.edgewall.com/repos/trac/plugins/0.12/spam-filter-captcha
     74}}}
     75
     76==== Enabling the plugin
     77
     78Unlike plugins installed per-environment, you'll have to explicitly enable globally installed plugins via [wiki:TracIni trac.ini]. This also applies to plugins installed in the shared plugins directory, ie the path specified in the `[inherit] plugins_dir` configuration option.
     79
     80This is done in the `[components]` section of the configuration file. For example:
     81{{{#!ini
    8082[components]
    8183tracspamfilter.* = enabled
    8284}}}
    8385
    84 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`.)
    85 
    86 Note: After installing the plugin, you need to restart your web server.
    87 
    88 ==== Uninstalling ====
    89 
    90 `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:
     86The 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
     88After installing the plugin, you must 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:
     93
    9194 1. Do `easy_install -m [plugin name]` to remove references from `$PYTHONLIB/site-packages/easy-install.pth` when the plugin installed by setuptools.
    92  1. Delete executables from `/usr/bin`, `/usr/local/bin` or `C:\\Python*\Scripts`. For search what executables are there, you may refer to `[console-script]` section of `setup.py`.
    93  1. Delete the .egg file or folder from where it is installed, usually inside `$PYTHONLIB/site-packages/`.
    94  1. Restart web server.
    95 
    96 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):
    97 {{{
     95 1. Delete executables from `/usr/bin`, `/usr/local/bin`, or `C:\\Python*\Scripts`. To find what executables are involved, refer to the `[console-script]` section of `setup.py`.
     96 1. Delete the .egg file or folder from where it's installed (usually inside `$PYTHONLIB/site-packages/`).
     97 1. Restart the web server.
     98
     99If you are uncertain about the location of the egg, here's a small tip to help locate an egg (or any package). Just replace `myplugin` with whatever namespace the plugin uses (as used when enabling the plugin):
     100{{{#!pycon
    98101>>> import myplugin
    99102>>> print myplugin.__file__
    … …  
    101104}}}
    102105
    103 == Setting up the Plugin Cache ==
    104 
    105 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.
    106 
    107 To do this from the Apache configuration, use the `SetEnv` directive as follows:
    108 {{{
     106== Setting up the plugin cache
     107
     108Some plugins will need to be extracted by the Python eggs runtime (`pkg_resources`), so that their contents are actual files on the file system. The directory in which they are extracted defaults to `.python-eggs` in the home directory of the current user, which may or may not be a problem. You can, however, override the default location using the `PYTHON_EGG_CACHE` environment variable.
     109
     110To do this from the Apache configuration, use the `SetEnv` directive:
     111{{{#!apache
    109112SetEnv PYTHON_EGG_CACHE /path/to/dir
    110113}}}
    111114
    112 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.
     115This 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.
    113116
    114117For example (for CGI):
    115 {{{
     118{{{#!apache
    116119 <Location /trac>
    117120   SetEnv TRAC_ENV /path/to/projenv
    … …  
    120123}}}
    121124
    122 or (for mod_python):
    123 {{{
     125Or (for mod_python):
     126{{{#!apache
    124127 <Location /trac>
    125128   SetHandler mod_python
    … …  
    129132}}}
    130133
    131  ''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.''
     134'''Note''': !SetEnv requires the `mod_env` module which needs to be activated for Apache. In this case the !SetEnv directive can also be used in the `mod_python` Location block.
    132135
    133136For [wiki:TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
    134137
    135  ''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.
    136 
    137 {{{
     138'''Note''': that if you already use -initial-env to set the project directory for either a single project or parent you will need to add an additional -initial-env directive to the !FastCgiConfig directive:
     139
     140{{{#!apache
    138141FastCgiConfig -initial-env TRAC_ENV=/var/lib/trac -initial-env PYTHON_EGG_CACHE=/var/lib/trac/plugin-cache
    139142}}}
    140143
    141 === About hook scripts ===
    142 
    143 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.
    144 
    145 == Troubleshooting ==
    146 
    147 === Is setuptools properly installed? ===
     144=== About hook scripts
     145
     146If you've set up some subversion hook scripts that call the Trac engine, such as the post-commit hook script provided in the `/contrib` directory, make sure you define the `PYTHON_EGG_CACHE` environment variable within these scripts as well.
     147
     148== Troubleshooting
     149
     150=== Is setuptools properly installed?
    148151
    149152Try this from the command line:
    150 {{{
     153{{{#!sh
    151154$ python -c "import pkg_resources"
    152155}}}
    … …  
    154157If you get '''no output''', setuptools '''is''' installed. Otherwise, you'll need to install it before plugins will work in Trac.
    155158
    156 === Did you get the correct version of the Python egg? ===
     159=== Did you get the correct version of the Python egg?
    157160
    158161Python 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).
    159162
    160 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.
    161 
    162 === Is the plugin enabled? ===
    163 
    164 
    165 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:
    166  * you actually added the necessary line(s) to the `[components]` section
    167  * the package/module names are correct
    168  * the value is “enabled", not e.g. “enable”
    169 
    170 === Check the permissions on the egg file ===
    171 
    172 Trac must be able to read the file.
    173 
    174 === Check the log files ===
     163Also, 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.
     164
     165=== Is the plugin enabled?
     166
     167If 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:
     168
     169 * you actually added the necessary line(s) to the `[components]` section.
     170 * the package/module names are correct.
     171 * the value is "enabled", not "enable" or "Enable".
     172 * the section name is "components", not "component".
     173
     174=== Check the permissions on the .egg file
     175
     176Trac must be able to read the .egg file.
     177
     178=== Check the log files
    175179
    176180Enable [wiki:TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins.
    177181
    178 === Verify you have proper permissions ===
     182=== Verify you have proper permissions
    179183
    180184Some 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.
    181185
    182 === Is the wrong version of the plugin loading? ===
     186=== Is the wrong version of the plugin loading?
    183187
    184188If 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:
    185  * 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.
    186  * 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.
    187  * 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.
    188  * 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.
    189 
    190 === If all of the above failed ===
    191 
    192 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.
     189
     190 * Only one version of the plugin can be loaded for each running Trac server (i.e., each Python process). The Python namespaces and module list will be shared, and it cannot handle duplicates. Whether a plugin is `enabled` or `disabled` makes no difference.
     191 * A globally-installed plugin (typically `setup.py install`) will override any version in the global or project plugins directories. A plugin from the global plugins directory will be located ''before'' any project plugins directory.
     192 * If your Trac server hosts more than one project (as with `TRAC_ENV_PARENT_DIR` setups), having two versions of a plugin in two different projects will give uncertain results. Only one of them will load, and the one loaded will be shared by both projects. Trac will load the first plugin found, usually from the project that receives the first request.
     193 * Having more than one version listed inside Python site-packages is fine (i.e., installed with `setup.py install`) -- setuptools will make sure you get the version installed most recently. However, don't store more than one version inside a global or project plugins directory -- neither version number nor installed date will matter at all. There is no way to determine which one will be located first when Trac searches the directory for plugins.
     194
     195=== If all of the above failed
     196
     197Okay, so the logs don't mention plugins, the egg is readable, the Python version is correct, ''and'' the egg has been installed globally (and is enabled in trac.ini)... and it ''still'' doesn't work or give any error messages or any other indication as to why. Hop on the [trac:IrcChannel IrcChannel] and ask away!
     198
     199== Web-based plugin administration
     200
     201The [trac:WebAdmin] interface offers limited support for plugin configuration through the web to users with `TRAC_ADMIN` permission:
     202
     203* en/disabling installed plugins
     204* installing plugins by uploading them as eggs
     205
     206If you wish to disable the second function for security reasons, add the following to the `[components]` section of trac.ini:
     207{{{#!ini
     208trac.admin.web_ui.PluginAdminPanel = disabled
     209}}}
     210This disables the whole panel, so the first function will no longer be available either.
    193211
    194212----
    195 See also TracGuide, [trac:PluginList plugin list], [trac:TracDev/ComponentArchitecture component architecture]
     213See also TracGuide, [trac:PluginList plugin list], [trac:TracDev/ComponentArchitecture component architecture].