Since v3.4.0, Tutor comes with a plugin system that allows anyone to customise the deployment of an Open edX platform very easily. The vision behind this plugin system is that users should not have to fork the Tutor repository to customise their deployments. For instance, if you have created a new application that integrates with Open edX, you should not have to describe how to manually patch the platform settings, ``urls.py`` or ``*.env.json`` files. Instead, you can create a "tutor-myapp" plugin for Tutor. Then, users will start using your application in three simple steps::
# 1) Install the plugin
pip install tutor-myapp
# 2) Enable the plugin
tutor plugins enable myapp
# 3) Restart the platform
tutor local quickstart
Commands
--------
List installed plugins::
tutor plugins list
Enable/disable a plugin::
tutor plugins enable myplugin
tutor plugins disable myplugin
After enabling or disabling a plugin, the environment should be re-generated with::
tutor config save
API (v0)
--------
Note: The API for developing Tutor plugins is still considered unstable: profound changes should be expected for some time.
There are two mechanisms by which a plugin can integrate with Tutor: patches and hooks. Patches affect the rendered environment templates, while hooks are actions that are run during the lifetime of an Open edX platform. A plugin indicates which templates it patches, and which hooks it needs to run. A plugin can also affect the project configuration by adding new values and modifying existing values.
*``config["add"]`` are key/values that should be added to the user-specific ``config.yml`` configuration. Add there passwords, secret keys and other values that do not have a default value.
*``config["defaults"]`` are default key/values for this plugin. These values will not be added to the ``config.yml`` user file unless users override them manually with ``tutor config save --set ...``.
*``config["set"]`` are existing key/values that should be modified. Be very careful what you add there! Plugins may define conflicting values for some parameters.
"set" and "default" key names will be automatically prefixed with the plugin name, in upper case.
This configuration from the "myplugin" plugin will set the following values:
-``MYPLUGIN_SECRET_KEY``: an 8-character random string will be generated and stored in the user configuration.
-``MYPLUGIN_DOCKER_IMAGE``: this value will by default not be stored in ``config.yml``, but ``tutor config printvalue MYPLUGIN_DOCKER_IMAGE`` will print ``username/imagename:latest``.
-``MASTER_PASSWORD`` will be set to ``h4cked``. Needless to say, plugin developers should avoid doing this.
The Tutor templates include calls to ``{{ patch("patchname") }}`` in many different places. Plugins can add content in these places by adding values to the ``patches`` attribute.
The ``patches`` attribute can be a callable function instead of a static attribute.
Example::
patches = {
"local-docker-compose-services": """redis:
image: redis:latest"""
}
This will add a Redis instance to the services run with ``tutor local`` commands.
During initialisation, "myservice1" and "myservice2" will be run in sequence with the commands defined in the templates ``myplugin/hooks/myservice1/init`` and ``myplugin/hooks/myservice2/init``.
This hook will be executed just before the ``init`` hooks. Otherwise, the specs are identical. This is useful for creating databases or other resources that will be required during initialisation, for instance.
In order to define plugin-specific hooks, a plugin should also have a template directory that includes the plugin hooks. The ``templates`` attribute should point to that directory.
A plugin can provide custom command line commands. Commands are assumed to be `click.Command <https://click.palletsprojects.com/en/7.x/api/#commands>`__ objects.
Example::
import click
@click.command(help="I'm a plugin command")
def command():
click.echo("Hello from myplugin!")
Any user who installs the ``myplugin`` plugin can then run::
$ tutor myplugin
Hello from myplugin!
You can even define subcommands by creating `command groups <https://click.palletsprojects.com/en/7.x/api/#click.Group>`__::
import click
@click.group(help="I'm a plugin command group")
def command():
pass
@click.command(help="I'm a plugin subcommand")
def dosomething():
click.echo("This subcommand is awesome")
This would allow any user to run::
$ tutor myplugin dosomething
This subcommand is awesome
See the official `click documentation <https://click.palletsprojects.com/en/7.x/>`__ for more information.
Creating a new plugin for Tutor is not so hard! You can get started with the `tutor plugin cookiecutter <https://github.com/overhangio/cookiecutter-tutor-plugin>`__::
