Changes between Version 2 and Version 3 of TracPlugins


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Timestamp:
Aug 13, 2019, 3:52:01 PM (5 years ago)
Author:
trac
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  • TracPlugins

    v2 v3  
    1 = Trac plugins = 
    2 [[TracGuideToc]] 
    3  
    4 From version 0.9 onwards, Trac is extensible with [trac:PluginList plugins]. Plugin functionality is based on the [trac:TracDev/ComponentArchitecture component architecture], with peculiarities described in the [TracDev/PluginDevelopment plugin development] page. 
    5  
    6 == Plugin discovery == 
    7  
    8 From 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. 
    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. 
     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. 
    1314 
    1415To install `setuptools`, download the bootstrap module [http://peak.telecommunity.com/dist/ez_setup.py ez_setup.py] and execute it as follows: 
    1516 
    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. 
     21If the `ez_setup.py` script fails to install the setuptools release, you can download it from [pypi:setuptools PyPI] and install it manually. 
    2122 
    2223Plugins can also consist of a single `.py` file dropped directly into either the project's or the shared `plugins` directory. 
    2324 
    24 == Installing a Trac plugin == 
    25  
    26 === For a single project === 
    27  
    28 Plugins are typically packaged as [http://peak.telecommunity.com/DevCenter/PythonEggs Python eggs]. That means they are .zip archives with the file extension `.egg`. 
     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 
    2930 
    3031If you have downloaded a source distribution of a plugin, and want to build the `.egg` file: 
    … …  
    3233 * Unpack the source. It should provide `setup.py`. 
    3334 * Run: 
    34  
    35 {{{ 
     35 {{{#!sh 
    3636$ python setup.py bdist_egg 
    3737}}} 
    3838 
    39 You should have a *.egg file. Examine the output of running python to find where this was created. 
    40  
    41 Once 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). 
     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. 
    4242 
    4343To uninstall a plugin installed this way, remove the egg from the `plugins` directory and restart the web server. 
    4444 
    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're running Trac under Python 2.5, but have upgraded your standalone Python to 2.6, the eggs won't be recognized. 
    46  
    47 Note also: 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  
    53 Some plugins (such as [trac:SpamFilter SpamFilter]) are downloadable as an `.egg` file that 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-0.4.1_r10106-py2.6.egg 
    63 }}} 
    64 You should end up with a directory having the same name as the zipped egg (complete with `.egg` extension) and containing its uncompressed contents. 
    65  
    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 ==== 
     45'''Note''': the Python version that the egg is built with ''must'' match the Python version with which Trac is run. For example, if you are running Trac under Python 2.6, but have upgraded your standalone Python to 2.7, the eggs won't be recognized. 
     46 
     47'''Note''': in a multi-project setup, a pool of Python interpreter instances will be dynamically allocated to projects based on need; since plugins occupy a place in Python's module system, the first version of any given plugin to be loaded will be used for all projects. In other words, you cannot use different versions of a single plugin in two projects of a multi-project setup. It may be safer to install plugins for all projects (see below), and then enable them selectively on a project-by-project basis. 
     48 
     49=== For all projects 
     50 
     51==== With an .egg file 
     52 
     53Some plugins, such as [https://trac-hacks.org/wiki/TagsPlugin TracTags], are downloadable as an `.egg` file that can be installed with `easy_install` or `pip`: 
     54{{{#!sh 
     55$ easy_install TracTags 
     56$ pip install TracTags 
     57}}} 
     58 
     59If `easy_install` is not on your system, see the Requirements section above to install it. Windows users will need to add the `Scripts` directory of their Python installation (for example, `C:\Python27\Scripts`) to their `PATH` environment variable, or use the full path to `easy_install` (for example, `C:\Python27\Scripts\easy_install.py`). See [http://peak.telecommunity.com/DevCenter/EasyInstall#windows-notes easy_install Windows notes] for more information. 
     60 
     61`pip` is included in Python 2.7.9. In earlier versions of Python it can be installed through the package manager of your OS (e.g. `apt-get install python-pip`) or using the [https://pip.pypa.io/en/latest/installing.html#install-pip get_pip.py].  
     62 
     63If Trac reports permission errors after installing a zipped egg, and you would rather not bother providing an egg cache directory writable by the web server, you can get around it by simply unzipping the egg. Just pass `--always-unzip` to `easy_install`: 
     64{{{#!sh 
     65$ easy_install --always-unzip TracTags 
     66}}} 
     67You should end up with a directory having the same name as the zipped egg, complete with `.egg` extension, and containing its uncompressed contents. 
     68 
     69Trac also searches for plugins installed in the shared plugins directory, see TracIni#GlobalConfiguration. This is a convenient way to share the installation of plugins across several, but not all, environments. 
     70 
     71==== From source 
    6972 
    7073`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/0.12/spam-filter-captcha 
    73 }}} 
    74  
    75 ==== Enabling the plugin ==== 
    76  
    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 the 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 {{{ 
     74{{{#!sh 
     75$ easy_install https://trac-hacks.org/svn/tagsplugin/trunk 
     76}}} 
     77 
     78==== Enabling the plugin 
     79 
     80Unlike plugins installed per environment, you'll have to explicitly enable globally installed plugins via [wiki:TracIni trac.ini]. This also applies to plugins installed in the shared plugins directory, ie the path specified in the `[inherit] plugins_dir` configuration option.  
     81 
     82This is done in the `[components]` section of the configuration file `trac.ini`. For example: 
     83{{{#!ini 
    8184[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 must 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: 
     85tractags.* = enabled 
     86}}} 
     87 
     88The name of the option is the Python package of the plugin. This should be specified in the documentation of the plugin, but can also be easily discovered by looking at the source: look for a top-level directory that contains a file named `__init__.py`. 
     89 
     90After installing the plugin, you must restart your web server. 
     91 
     92==== Upgrading the environment 
     93 
     94Some plugins may require an environment upgrade. This will typically be necessary for plugins that implement `IEnvironmentSetupParticipant`. Common reasons for requiring an environment upgrade are to add tables to the database or add configuration parameters to trac.ini. A notification will be displayed when accessing Trac for the first time after installing a plugin and restarting the web server. To upgrade the environment, run the command: 
     95 
     96{{{#!sh 
     97$ trac-admin /path/to/env upgrade 
     98}}} 
     99 
     100A database backup will be made before upgrading the environment, unless the `--no-backup` option is specified. For more information, refer to the documentation output by `trac-admin /path/to/env help upgrade`. 
     101 
     102==== Uninstalling 
     103 
     104Neither `easy_install` nor `python setup.py` have an uninstall feature. However, it is usually trivial to remove a globally installed egg and reference: 
    92105 
    93106 1. Do `easy_install -m [plugin name]` to remove references from `$PYTHONLIB/site-packages/easy-install.pth` when the plugin installed by setuptools. 
    94107 1. Delete executables from `/usr/bin`, `/usr/local/bin`, or `C:\\Python*\Scripts`. To find what executables are involved, refer to the `[console-script]` section of `setup.py`. 
    95  1. Delete the .egg file or folder from where it's installed (usually inside `$PYTHONLIB/site-packages/`). 
     108 1. Delete the .egg file or folder from where it's installed, usually inside `$PYTHONLIB/site-packages/`. 
    96109 1. Restart the web server. 
    97110 
    98 If 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): 
    99 {{{ 
     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. 
     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. 
    108121 
    109122To do this from the Apache configuration, use the `SetEnv` directive: 
    110 {{{ 
     123{{{#!apache 
    111124SetEnv PYTHON_EGG_CACHE /path/to/dir 
    112125}}} 
    113126 
    114 This 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], 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'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. 
    146  
    147 == Troubleshooting == 
    148  
    149 === Is setuptools properly installed? === 
    150  
    151 Try this from the command line: 
    152 {{{ 
    153 $ python -c "import pkg_resources" 
    154 }}} 
    155  
    156 If you get '''no output''', setuptools '''is''' installed. Otherwise, you'll need to install it before plugins will work in Trac. 
    157  
    158 === Did you get the correct version of the Python egg? === 
    159  
    160 Python 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). 
    161  
    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 If 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: 
    167  
    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 "enable" or "Enable". 
    171  
    172 === Check the permissions on the .egg file === 
    173  
    174 Trac must be able to read the .egg file.  
    175  
    176 === Check the log files === 
    177  
    178 Enable [wiki:TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins. 
    179  
    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? === 
    185  
    186 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: 
    187  
    188  * 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. 
    189  * 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. 
    190  * 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. 
    191  * 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. 
    192  
    193 === If all of the above failed === 
    194  
    195 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] and ask away! 
    196  
    197 == Web-based plugin administration == 
    198  
    199 The WebAdmin plugin (part of the core since 0.11) offers limited support for plugin configuration through the web to users with `TRAC_ADMIN` permission: 
     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: 
    200163 
    201164* en/disabling installed plugins 
    202165* installing plugins by uploading them as eggs 
    203166 
    204 You probably want to disable the second function for security reasons: in `trac.ini`, in the `[components]` section, add the line 
    205 {{{ 
     167If you wish to disable the second function for security reasons, add the following to your `trac.ini` file: 
     168{{{#!ini 
     169[components] 
    206170trac.admin.web_ui.PluginAdminPanel = disabled 
    207171}}} 
    208172This disables the whole panel, so the first function will no longer be available either. 
     173 
     174== Troubleshooting 
     175 
     176=== Is setuptools properly installed? 
     177 
     178Try this from the command line: 
     179{{{#!sh 
     180$ python -c "import pkg_resources" 
     181}}} 
     182 
     183If you get '''no output''', setuptools '''is''' installed. Otherwise, you'll need to install it before plugins will work in Trac. 
     184 
     185=== Did you get the correct version of the Python egg? 
     186 
     187Python eggs have the Python version encoded in their filename. For example, `MyPlugin-1.0-py2.5.egg` is an egg for Python 2.5, and will '''not''' be loaded if you're running a different Python version (such as 2.4 or 2.6). 
     188 
     189Also, verify that the egg file you downloaded is indeed a .zip archive. If you downloaded it from a Trac site, chances are you downloaded the HTML preview page instead. 
     190 
     191=== Is the plugin enabled? 
     192 
     193If you install a plugin globally, ie ''not'' inside the `plugins` directory of the Trac project environment, you must explicitly enable it in [TracIni trac.ini]. Make sure that: 
     194 
     195 * you actually added the necessary line(s) to the `[components]` section. 
     196 * the package/module names are correct and do not contain typos. 
     197 * the value is "enabled", not "enable" or "Enable". 
     198 * the section name is "components", not "component". 
     199 
     200=== Check the permissions on the .egg file 
     201 
     202Trac must be able to read the .egg file.  
     203 
     204=== Check the log files 
     205 
     206Enable [wiki:TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins. 
     207 
     208=== Verify you have the proper permissions 
     209 
     210Some plugins require you have special permissions in order to use them. [trac:WebAdmin WebAdmin], for example, requires the user to have `TRAC_ADMIN` permissions for it to show up on the navigation bar. 
     211 
     212=== Is the wrong version of the plugin loading? 
     213 
     214If you put your plugins inside plugins directories, and certainly if you have more than one project, you need to make sure that the correct version of the plugin is loading. Here are some basic rules: 
     215 
     216 * Only one version of the plugin can be loaded for each running Trac server, ie each Python process. The Python namespaces and module list will be shared, and it cannot handle duplicates. Whether a plugin is `enabled` or `disabled` makes no difference. 
     217 * A globally installed plugin (typically `setup.py install`) will override any version in the global or project plugins directories. A plugin from the global plugins directory will be located ''before'' any project plugins directory. 
     218 * If your Trac server hosts more than one project (as with `TRAC_ENV_PARENT_DIR` setups), having two versions of a plugin in two different projects will give unpredicatable results. Only one of them will load, and the one loaded will be shared by both projects. Trac will load the first plugin found, usually from the project that receives the first request. 
     219 * Having more than one version listed inside Python site-packages is fine, ie installed with `setup.py install`, because setuptools will make sure you get the version installed most recently. However, don't store more than one version inside a global or project plugins directory: neither the version number nor the installed date will matter at all. There is no way to determine which one will be located first when Trac searches the directory for plugins. 
     220 
     221=== If all of the above failed 
     222 
     223Okay, so the logs don't mention plugins, the egg is readable, the Python version is correct, ''and'' the egg has been installed globally (and is enabled in trac.ini)... and it ''still'' doesn't work or give any error messages or any other indication as to why. Hop on the [trac:IrcChannel IrcChannel] and ask away! 
    209224 
    210225----