MkDocs Plugins

A Guide to installing, using and creating MkDocs Plugins

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Installing Plugins

Before a plugin can be used, it must be installed on the system. If you are using a plugin which comes with MkDocs, then it was installed when you installed MkDocs. However, to install third party plugins, you need to determine the appropriate package name and install it using pip:

pip install mkdocs-foo-plugin

Once a plugin has been successfully installed, it is ready to use. It just needs to be enabled in the configuration file. The MkDocs Plugins wiki page has a growing list of plugins that you can install and use.

Using Plugins

The plugins configuration option should contain a list of plugins to use when building the site. Each "plugin" must be a string name assigned to the plugin (see the documentation for a given plugin to determine its "name"). A plugin listed here must already be installed.

plugins:
    - search

Some plugins may provide configuration options of their own. If you would like to set any configuration options, then you can nest a key/value mapping (option_name: option value) of any options that a given plugin supports. Note that a colon (:) must follow the plugin name and then on a new line the option name and value must be indented and separated by a colon. If you would like to define multiple options for a single plugin, each option must be defined on a separate line.

plugins:
    - search:
        lang: en
        foo: bar

For information regarding the configuration options available for a given plugin, see that plugin's documentation.

For a list of default plugins and how to override them, see the configuration documentation.

Developing Plugins

Like MkDocs, plugins must be written in Python. It is generally expected that each plugin would be distributed as a separate Python module, although it is possible to define multiple plugins in the same module. At a minimum, a MkDocs Plugin must consist of a BasePlugin subclass and an entry point which points to it.

BasePlugin

A subclass of mkdocs.plugins.BasePlugin should define the behavior of the plugin. The class generally consists of actions to perform on specific events in the build process as well as a configuration scheme for the plugin.

All BasePlugin subclasses contain the following attributes:

config_scheme

: A tuple of configuration validation instances. Each item must consist of a two item tuple in which the first item is the string name of the configuration option and the second item is an instance of mkdocs.config.config_options.BaseConfigOption or any of its subclasses.

For example, the following `config_scheme` defines three configuration options: `foo`, which accepts a string; `bar`, which accepts an integer; and `baz`, which accepts a boolean value.

    class MyPlugin(mkdocs.plugins.BasePlugin):
        config_scheme = (
            ('foo', mkdocs.config.config_options.Type(str, default='a default value')),
            ('bar', mkdocs.config.config_options.Type(int, default=0)),
            ('baz', mkdocs.config.config_options.Type(bool, default=True))
        )

When the user's configuration is loaded, the above scheme will be used to
validate the configuration and fill in any defaults for settings not
provided by the user. The validation classes may be any of the classes
provided in `mkdocs.config.config_options` or a third party subclass defined
in the plugin.

Any settings provided by the user which fail validation or are not defined
in the `config_scheme` will raise a `mkdocs.config.base.ValidationError`.

config

: A dictionary of configuration options for the plugin, which is populated by the load_config method after configuration validation has completed. Use this attribute to access options provided by the user.

    def on_pre_build(self, config):
        if self.config['bool_option']:
            # implement "bool_option" functionality here...

All BasePlugin subclasses contain the following method(s):

load_config(options)

: Loads configuration from a dictionary of options. Returns a tuple of (errors, warnings). This method is called by MkDocs during configuration validation and should not need to be called by the plugin.

on_<event_name>()

: Optional methods which define the behavior for specific events. The plugin should define its behavior within these methods. Replace <event_name> with the actual name of the event. For example, the pre_build event would be defined in the on_pre_build method.

Most events accept one positional argument and various keyword arguments. It
is generally expected that the positional argument would be modified (or
replaced) by the plugin and returned. If nothing is returned (the method
returns `None`), then the original, unmodified object is used. The keyword
arguments are simply provided to give context and/or supply data which may
be used to determine how the positional argument should be modified. It is
good practice to accept keyword arguments as `**kwargs`. In the event that
additional keywords are provided to an event in a future version of MkDocs,
there will be no need to alter your plugin.

For example, the following event would add an additional static_template to
the theme config:

    class MyPlugin(BasePlugin):
        def on_config(self, config, **kwargs):
            config['theme'].static_templates.add('my_template.html')
            return config

Events

There are three kinds of events: Global Events, Page Events and Template Events.

Global Events

Global events are called once per build at either the beginning or end of the build process. Any changes made in these events will have a global effect on the entire site.

on_serve

: The serve event is only called when the serve command is used during development. It is passed the Server instance which can be modified before it is activated. For example, additional files or directories could be added to the list of "watched" files for auto-reloading.

Parameters:
: __server:__ `livereload.Server` instance
: __config:__ global configuration object
: __builder:__ a callable which gets passed to each call to `server.watch`

Returns:
: `livereload.Server` instance

on_config

: The config event is the first event called on build and is run immediately after the user configuration is loaded and validated. Any alterations to the config should be made here.

Parameters:
: __config:__ global configuration object

Returns:
: global configuration object

on_pre_build

: The pre_build event does not alter any variables. Use this event to call pre-build scripts.

Parameters:
: __config:__ global configuration object

on_files

: The files event is called after the files collection is populated from the docs_dir. Use this event to add, remove, or alter files in the collection. Note that Page objects have not yet been associated with the file objects in the collection. Use Page Events to manipulate page specific data.

Parameters:
: __files:__ global files collection
: __config:__ global configuration object

Returns:
: global files collection

on_nav

: The nav event is called after the site navigation is created and can be used to alter the site navigation.

Parameters:
: __nav:__ global navigation object
: __config:__ global configuration object
: __files:__ global files collection

Returns:
: global navigation object

on_env

: The env event is called after the Jinja template environment is created and can be used to alter the Jinja environment.

Parameters:
: __env:__ global Jinja environment
: __config:__ global configuration object
: __files:__ global files collection

Returns:
: global Jinja Environment

on_post_build

: The post_build event does not alter any variables. Use this event to call post-build scripts.

Parameters:
: __config:__ global configuration object

on_build_error

: The build_error event is called after an exception of any kind is caught by MkDocs during the build process. Use this event to clean things up before MkDocs terminates. Note that any other events which were scheduled to run after the error will have been skipped. See Handling Errors for more details.

Parameters:
: __error:__ exception raised

Template Events

Template events are called once for each non-page template. Each template event will be called for each template defined in the extra_templates config setting as well as any static_templates defined in the theme. All template events are called after the env event and before any page events.

on_pre_template

: The pre_template event is called immediately after the subject template is loaded and can be used to alter the content of the template.

Parameters:
: __template__: the template contents as string
: __template_name__: string filename of template
: __config:__ global configuration object

Returns:
: template contents as string

on_template_context

: The template_context event is called immediately after the context is created for the subject template and can be used to alter the context for that specific template only.

Parameters:
: __context__: dict of template context variables
: __template_name__: string filename of template
: __config:__ global configuration object

Returns:
: dict of template context variables

on_post_template

: The post_template event is called after the template is rendered, but before it is written to disc and can be used to alter the output of the template. If an empty string is returned, the template is skipped and nothing is is written to disc.

Parameters:
: __output_content__: output of rendered template as string
: __template_name__: string filename of template
: __config:__ global configuration object

Returns:
: output of rendered template as string

Page Events

Page events are called once for each Markdown page included in the site. All page events are called after the post_template event and before the post_build event.

on_pre_page

: The pre_page event is called before any actions are taken on the subject page and can be used to alter the Page instance.

Parameters:
: __page:__ `mkdocs.nav.Page` instance
: __config:__ global configuration object
: __files:__ global files collection

Returns:
: `mkdocs.nav.Page` instance

on_page_read_source

: The on_page_read_source event can replace the default mechanism to read the contents of a page's source from the filesystem.

Parameters:
: __page:__ `mkdocs.nav.Page` instance
: __config:__ global configuration object

Returns:
: The raw source for a page as unicode string. If `None` is returned, the
  default loading from a file will be performed.

on_page_markdown

: The page_markdown event is called after the page's markdown is loaded from file and can be used to alter the Markdown source text. The meta- data has been stripped off and is available as page.meta at this point.

Parameters:
: __markdown:__ Markdown source text of page as string
: __page:__ `mkdocs.nav.Page` instance
: __config:__ global configuration object
: __files:__ global files collection

Returns:
: Markdown source text of page as string

on_page_content

: The page_content event is called after the Markdown text is rendered to HTML (but before being passed to a template) and can be used to alter the HTML body of the page.

Parameters:
: __html:__ HTML rendered from Markdown source as string
: __page:__ `mkdocs.nav.Page` instance
: __config:__ global configuration object
: __files:__ global files collection

Returns:
: HTML rendered from Markdown source as string

on_page_context

: The page_context event is called after the context for a page is created and can be used to alter the context for that specific page only.

Parameters:
: __context__: dict of template context variables
: __page:__ `mkdocs.nav.Page` instance
: __config:__ global configuration object
: __nav:__ global navigation object

Returns:
: dict of template context variables

on_post_page

: The post_page event is called after the template is rendered, but before it is written to disc and can be used to alter the output of the page. If an empty string is returned, the page is skipped and nothing is written to disc.

Parameters:
: __output:__ output of rendered template as string
: __page:__ `mkdocs.nav.Page` instance
: __config:__ global configuration object

Returns:
: output of rendered template as string

Handling Errors

MkDocs defines four error types:

mkdocs.exceptions.MkDocsException

: The base class which all MkDocs exceptions inherit from. This should not be raised directly. One of the sublcasses should be raised instead.

mkdocs.exceptions.ConfigurationError

: This error is raised by configuration validation when a validation error is encountered. This error should be raised by any configuration options defined in a plugin's config_scheme.

mkdocs.exceptions.BuildError

: This error may be raised by MkDocs during the build process. Plugins should not raise this error.

mkdocs.exceptions.PluginError

: A subclass of mkdocs.exceptions.BuildError which can be raised by plugin events.

Unexpected and uncaught exceptions will interrupt the build process and produce typical Python tracebacks, which are useful for debugging your code. However, users generally find tracebacks overwhelming and often miss the helpful error message. Therefore, MkDocs will catch any of the errors listed above, retrieve the error message, and exit immediately with only the helpful message displayed to the user.

Therefore, you might want to catch any exceptions within your plugin and raise a PluginError, passing in your own custom-crafted message, so that the build process is aborted with a helpful message.

The on_build_error event will be triggered for any exception.

For example:

from mkdocs.exceptions import PluginError
from mkdocs.plugins import BasePlugin


class MyPlugin(BasePlugin):
    def on_post_page(self, output, page, config, **kwargs):
        try:
            # some code that could throw a KeyError
            ...
        except KeyError as error:
            raise PluginError(str(error))

    def on_build_error(self, error):
        # some code to clean things up
        ...

Entry Point

Plugins need to be packaged as Python libraries (distributed on PyPI separate from MkDocs) and each must register as a Plugin via a setuptools entry_point. Add the following to your setup.py script:

entry_points={
    'mkdocs.plugins': [
        'pluginname = path.to.some_plugin:SomePluginClass',
    ]
}

The pluginname would be the name used by users (in the config file) and path.to.some_plugin:SomePluginClass would be the importable plugin itself (from path.to.some_plugin import SomePluginClass) where SomePluginClass is a subclass of BasePlugin which defines the plugin behavior. Naturally, multiple Plugin classes could exist in the same module. Simply define each as a separate entry_point.

entry_points={
    'mkdocs.plugins': [
        'featureA = path.to.my_plugins:PluginA',
        'featureB = path.to.my_plugins:PluginB'
    ]
}

Note that registering a plugin does not activate it. The user still needs to tell MkDocs to use it via the config.