Changes between Version 5 and Version 6 of Trac Plugins


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Timestamp:
Jul 18, 2015, 12:43:07 PM (9 years ago)
Author:
trac
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  • Trac Plugins

    v5 v6  
     1[[PageOutline(2-5,Contents,pullout)]]
     2
    13= Trac plugins
    24
    3 [[TracGuideToc]]
    4 
    5 Trac 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.
     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.
    66
    77== Plugin discovery
    88
    9 From 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 trac.ini.
     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.
    1010
    1111== Requirements for Trac eggs
    … …  
    1919}}}
    2020
    21 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.
    2222
    2323Plugins can also consist of a single `.py` file dropped directly into either the project's or the shared `plugins` directory.
    … …  
    3333 * Unpack the source. It should provide `setup.py`.
    3434 * Run:
    35 
    36 {{{#!sh
     35 {{{#!sh
    3736$ python setup.py bdist_egg
    3837}}}
    3938
    40 You should have a *.egg file. Examine the output of running Python to find where this was created.
    41 
    42 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.
    4342
    4443To uninstall a plugin installed this way, remove the egg from the `plugins` directory and restart the web server.
    4544
    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 2.6, but have upgraded your standalone Python to 2.7, the eggs won't be recognized.
     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.
    4746
    4847'''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.
    … …  
    6261`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].
    6362
    64 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`:
     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`:
    6564{{{#!sh
    6665$ easy_install --always-unzip TracSpamFilter-0.4.1_r10106-py2.6.egg
    6766}}}
    68 You should end up with a directory having the same name as the zipped egg (complete with `.egg` extension) and containing its uncompressed contents.
     67You should end up with a directory having the same name as the zipped egg, complete with `.egg` extension, and containing its uncompressed contents.
    6968
    7069Trac 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.
    … …  
    7978==== Enabling the plugin
    8079
    81 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, ie the path specified in the `[inherit] plugins_dir` configuration option.
    82 
    83 This is done in the `[components]` section of the configuration file. For example:
     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:
    8483{{{#!ini
    8584[components]
    … …  
    8786}}}
    8887
    89 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`).
     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`.
    9089
    9190After installing the plugin, you must restart your web server.
    … …  
    9392==== Uninstalling
    9493
    95 `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:
     94Neither `easy_install` nor `python setup.py` have an uninstall feature. However, it is usually trivial to remove a globally installed egg and reference:
    9695
    9796 1. Do `easy_install -m [plugin name]` to remove references from `$PYTHONLIB/site-packages/easy-install.pth` when the plugin installed by setuptools.
    9897 1. Delete executables from `/usr/bin`, `/usr/local/bin`, or `C:\\Python*\Scripts`. To find what executables are involved, refer to the `[console-script]` section of `setup.py`.
    99  1. Delete the .egg file or folder from where it's installed (usually inside `$PYTHONLIB/site-packages/`).
     98 1. Delete the .egg file or folder from where it's installed, usually inside `$PYTHONLIB/site-packages/`.
    10099 1. Restart the web server.
    101100
    102 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):
     101If 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):
    103102{{{#!pycon
    104103>>> import myplugin
    … …  
    109108== Setting up the plugin cache
    110109
    111 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.
     110Some 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.
    112111
    113112To do this from the Apache configuration, use the `SetEnv` directive:
    … …  
    118117This 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.
    119118
    120 For example (for CGI):
     119For example for CGI:
    121120{{{#!apache
    122121 <Location /trac>
    … …  
    126125}}}
    127126
    128 Or (for mod_python):
     127Or for mod_python:
    129128{{{#!apache
    130129 <Location /trac>
    … …  
    135134}}}
    136135
    137 '''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.
     136'''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.
    138137
    139138For [wiki:TracFastCgi FastCGI], you'll need to `-initial-env` option, or whatever is provided by your web server for setting environment variables.
    140139
    141 '''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:
     140'''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:
    142141
    143142{{{#!apache
    … …  
    147146=== About hook scripts
    148147
    149 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.
     148If 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.
     149
     150== Web-based plugin administration
     151
     152The [trac:WebAdmin] interface offers limited support for plugin configuration through the web to users with `TRAC_ADMIN` permission:
     153
     154* en/disabling installed plugins
     155* installing plugins by uploading them as eggs
     156
     157If you wish to disable the second function for security reasons, add the following to your `trac.ini` file:
     158{{{#!ini
     159[components]
     160trac.admin.web_ui.PluginAdminPanel = disabled
     161}}}
     162This disables the whole panel, so the first function will no longer be available either.
    150163
    151164== Troubleshooting
    … …  
    171184
    172185 * you actually added the necessary line(s) to the `[components]` section.
    173  * the package/module names are correct.
     186 * the package/module names are correct and do not contain typos.
    174187 * the value is "enabled", not "enable" or "Enable".
    175188 * the section name is "components", not "component".
    … …  
    183196Enable [wiki:TracLogging logging] and set the log level to `DEBUG`, then watch the log file for messages about loading plugins.
    184197
    185 === Verify you have proper permissions
    186 
    187 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.
     198=== Verify you have the proper permissions
     199
     200Some 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.
    188201
    189202=== Is the wrong version of the plugin loading?
    … …  
    191204If 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:
    192205
    193  * 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.
    194  * 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.
    195  * 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.
    196  * 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.
     206 * 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.
     207 * 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.
     208 * 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.
     209 * 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.
    197210
    198211=== If all of the above failed
    199212
    200213Okay, 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!
    201 
    202 == Web-based plugin administration
    203 
    204 The [trac:WebAdmin] interface offers limited support for plugin configuration through the web to users with `TRAC_ADMIN` permission:
    205 
    206 * en/disabling installed plugins
    207 * installing plugins by uploading them as eggs
    208 
    209 If you wish to disable the second function for security reasons, add the following to the `[components]` section of trac.ini:
    210 {{{#!ini
    211 trac.admin.web_ui.PluginAdminPanel = disabled
    212 }}}
    213 This disables the whole panel, so the first function will no longer be available either.
    214214
    215215----