100 lines
4.0 KiB
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100 lines
4.0 KiB
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==========================================
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Extending StoryBoard: Event Worker Plugins
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==========================================
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Overview
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--------
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It is sometimes useful to have a method to react to StoryBoard's API events.
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This can be done using Event Worker plugins, which recieve a notification
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whenever a POST, PUT, or DELETE action occurs on the API. The plugin can then
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decide how to process each event asynchronously so as not to impact the
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stability of the API.
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Your workers will be detected by `storyboard-worker-daemon` when it starts,
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and a number of worker processes will be created. When a daemon finds a
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message in the Rabbit queue, it passes the message to the handle() function
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of each worker plugin it has found.
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Note: In order for event worker plugins to work, your StoryBoard config file
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will need to contain `enable_notifications = True`.
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Event Worker Plugin Quickstart
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------------------------------
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Step 1: Create a new python project using setuptools
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####################################################
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This is left as an exercise to the reader. Don't forget to include storyboard
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as a requirement.
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Step 2: Implement your plugin
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#############################
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Add a registered entry point in your plugin's `setup.cfg`. The name should be
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reasonably unique::
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[entry_points]
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storyboard.plugin.worker =
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my-worker-plugin = my.namespace.plugin:MyEventWorker
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Then, implement your plugin by extending `WorkerTaskBase`. You may register
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your own configuration groups, please see
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`oslo.config <https://docs.openstack.org/oslo.config/latest/reference/cfg.html>`_
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for more details.::
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from storyboard.plugin.event_worker import WorkerTaskBase
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class MyEventWorker(WorkerTaskBase):
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def enabled(self):
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'''This method should return whether the plugin is enabled and
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configured. It has access to self.config, which is a reference to
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storyboard's global configuration object.
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'''
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return True
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def handle(self, session, author, method, path, status, resource,
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resource_id, sub_resource=None, sub_resource_id=None,
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resource_before=None, resource_after=None):
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"""This method takes information about an API event and does
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something with it, for example creating a SubscriptionEvent
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in the database for everyone subscribed to the affected resource.
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:param session: An event-specific SQLAlchemy session.
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:param author: The author's user record.
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:param method: The HTTP Method.
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:param path: The full HTTP Path requested.
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:param status: The returned HTTP Status of the response.
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:param resource: The resource type.
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:param resource_id: The ID of the resource.
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:param sub_resource: The subresource type.
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:param sub_resource_id: The ID of the subresource.
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:param resource_before: The resource state before this event occurred.
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:param resource_after: The resource state after this event occurred.
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"""
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if resource == 'timeline_event':
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event = db_api.entity_get(models.TimeLineEvent, resource_id,
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session=session)
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subscribers = sub_api.subscription_get_all_subscriber_ids(
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'story', event.story_id, session=session)
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for user_id in subscribers:
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event_info = event.event_info
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db_api.entity_create(models.SubscriptionEvents, {
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"author_id": author.id,
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"subscriber_id": user_id,
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"event_type": event.event_type,
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"event_info": event_info
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}, session=session)
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Step 3: Install your plugin
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###########################
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Finally, install your plugin, which may require you switch into storyboard's
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virtual environment. Pip should automatically register your plugin::
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pip install my-storyboard-plugin
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