Events

The OBS has a pub/sub event system built in.

Workflow

OBS sub-systems publish events and other OBS sub-systems then react to published events.

Events

Events describe something that happened throughout the OBS (backend and frontend). Things like

• The build of package FOO in project BAR has failed
• The submit request #12345 was accepted
• A comment was created in project FOO

Types of Events:

See Event::Base and classes inheriting from it (e.g. Event::CommentForProject or Event::RequestStatechange).

Publishing Events

We publish an event by creating an instance of Event in the database. The code below will, for instance, create an event that describes that a the package obs-server was branched by the user henne.

Event::BranchCommand.create(project: 'OBS:Server:Unstable',
                            package: 'obs-server',
                            targetproject: 'home:henne',
                            targetpackage: 'obs-server',
                            user: 'henne')

Throughout the app, Event instances get created by:

1. code like above
2. the OBS backend

Most of the events happen in the OBS backend. It exposes them on its /lastnotifications API. We poll this API periodically (via clockwork) with the UpdateNotificationEvents class. That class then creates instances of Event in the database.

Subscribing to Events

There are several subsystems that subscribe to the publishing of events and then do something.

• The Notifications sub-system is notifying people about events. This sub-system is triggered by many of the events.
• An ActiveJob is filling the ProjectLog with entries based on events. This job is scheduled by many of the events.
• Another ActiveJob keeps The-BackendPackage-Cache fresh. This job is scheduled by commit and service events.
• The UpdateReleasedBinariesJob ActiveJob tracks published packages. This job is scheduled by packtrack events.
• The RabbitmqBus. This sub-system is triggered by many of the events. See below.

Publishing Events to the Rabbitmq Message Bus

Many events are also published on the RabbitMQ message bus when they happen.

Event classes that respond to the the message_bus_routing_key method are send to the obs exchange. Event classes that respond to the method metric_fields are send to the metrics exchange.

Cleaning up Events

The CleanupEvents job destroys all the Event instances where the other subs-systems have done their job. This state is tracked in the Event instance.

Jobs that inherit from CreateJob increase the Event.undone_jobs attribute by 1 if they are scheduled. And subtract Event.undone_jobs attribute by 1 if they are finished. SendEventEmailsJob sets Event.mails_sent to true once it finishes.