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tutor/docs/plugins/v0/gettingstarted.rst

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Getting started with plugin development
=======================================
feat: migrate to plugins.v1 with filters & actions This is a very large refactoring which aims at making Tutor both more extendable and more generic. Historically, the Tutor plugin system was designed as an ad-hoc solution to allow developers to modify their own Open edX platforms without having to fork Tutor. The plugin API was simple, but limited, because of its ad-hoc nature. As a consequence, there were many things that plugin developers could not do, such as extending different parts of the CLI or adding custom template filters. Here, we refactor the whole codebase to make use of a generic plugin system. This system was inspired by the Wordpress plugin API and the Open edX "hooks and filters" API. The various components are added to a small core thanks to a set of actions and filters. Actions are callback functions that can be triggered at different points of the application lifecycle. Filters are functions that modify some data. Both actions and filters are collectively named as "hooks". Hooks can optionally be created within a certain context, which makes it easier to keep track of which application created which callback. This new hooks system allows us to provide a Python API that developers can use to extend their applications. The API reference is added to the documentation, along with a new plugin development tutorial. The plugin v0 API remains supported for backward compatibility of existing plugins. Done: - Do not load commands from plugins which are not enabled. - Load enabled plugins once on start. - Implement contexts for actions and filters, which allow us to keep track of the source of every hook. - Migrate patches - Migrate commands - Migrate plugin detection - Migrate templates_root - Migrate config - Migrate template environment globals and filters - Migrate hooks to tasks - Generate hook documentation - Generate patch reference documentation - Add the concept of action priority Close #499.
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.. include:: legacy.rst
Plugins can be created in two different ways: either as plain YAML files or installable Python packages. YAML files are great when you need to make minor changes to the default platform, such as modifying settings. For creating more complex applications, it is recommended to create python packages.
.. _plugins_yaml:
YAML file
~~~~~~~~~
YAML files that are stored in the tutor plugins root folder will be automatically considered as plugins. The location of the plugin root can be found by running::
tutor plugins printroot
On Linux, this points to ``~/.local/share/tutor-plugins``. The location of the plugin root folder can be modified by setting the ``TUTOR_PLUGINS_ROOT`` environment variable.
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YAML plugins must define two special top-level keys: ``name`` and ``version``. Then, YAML plugins may use two more top-level keys to customise Tutor's behaviour: ``config`` and ``patches``. Custom CLI commands, templates, and hooks are not supported by YAML plugins.
Let's create a simple plugin that adds your own `Google Analytics <https://analytics.google.com/>`__ tracking code to your Open edX platform. We need to add the ``GOOGLE_ANALYTICS_ACCOUNT`` and ``GOOGLE_ANALYTICS_TRACKING_ID`` settings to both the LMS and the CMS settings. To do so, we will only have to create the ``openedx-common-settings`` patch, which is shared by the development and the production settings both for the LMS and the CMS. First, create the plugin directory::
mkdir "$(tutor plugins printroot)"
Then add the following content to the plugin file located at ``$(tutor plugins printroot)/myplugin.yml``::
name: googleanalytics
version: 0.1.0
patches:
openedx-common-settings: |
# googleanalytics special settings
GOOGLE_ANALYTICS_ACCOUNT = "UA-654321-1"
GOOGLE_ANALYTICS_TRACKING_ID = "UA-654321-1"
Of course, you should replace your Google Analytics tracking code with your own. You can verify that your plugin is correctly installed, but not enabled yet::
$ tutor plugins list
googleanalytics@0.1.0 (disabled)
You can then enable your newly-created plugin::
tutor plugins enable googleanalytics
Update your environment to apply changes from your plugin::
tutor config save
You should be able to view your changes in every LMS and CMS settings file::
grep -r googleanalytics "$(tutor config printroot)/env/apps/openedx/settings/"
Now just restart your platform to start sending tracking events to Google Analytics::
tutor local launch
That's it! And it's very easy to share your plugins. Just upload them to your Github repo and share the url with other users. They will be able to install your plugin by running::
tutor plugins install https://raw.githubusercontent.com/username/yourrepo/master/googleanalytics.yml
Python package
~~~~~~~~~~~~~~
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Creating a plugin as a Python package allows you to define more complex logic and store your patches in a more structured way. Python Tutor plugins are regular Python packages that define an entry point within the ``tutor.plugin.v0`` group:
Example::
from setuptools import setup
setup(
...
entry_points={
"tutor.plugin.v0": ["myplugin = myplugin.plugin"]
},
)
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The ``myplugin/plugin.py`` Python module can then define the attributes ``config``, ``patches``, ``hooks``, and ``templates`` to specify the plugin's behaviour. The attributes may be defined either as dictionaries or as zero-argument callables returning dictionaries; in the latter case, the callable will be evaluated upon plugin load. Finally, the ``command`` attribute can be defined as an instance of ``click.Command`` to define the plugin's command line interface.
Example::
import click
templates = pkg_resources.resource_filename(...)
config = {...}
hooks = {...}
def patches():
...
@click.command(...)
def command():
...
To get started on the right foot, it is strongly recommended to create your first plugin with the `tutor plugin cookiecutter <https://github.com/overhangio/cookiecutter-tutor-plugin>`__::
pip install cookiecutter
cookiecutter https://github.com/overhangio/cookiecutter-tutor-plugin.git
pip install -e ./tutor-myplugin
tutor plugins list # your plugin should appear here
tutor plugins enable myplugin # hack at it!