Feature Overview 

Watcher has the option to consume notifications from nova that can be used to keep the compute model updated. Also it has the option to send notifications on any relevant event as creating an audit, actionplan, executing actions, etc....

Since FR3, nova-operator has the positility to use a separated message bus to send traffic (https://issues.redhat.com/browse/RHOSSTRAT-680 ), so it'd be good to be able to consume those notifications delivered by Nova.

Potentially, watcher could also send notifications if any service is interested on it.

Goals

Consuming notifications would provide a better way of managing the compute model in the watcher service so that the actual data being used by strategies would be up to date.

Providing notifications for watcher events may be interesting for external parties willing go be aware of when a watcher action has happened and the result of it and also to keep consistency with the rest of OpenStack services and operators. 

Acceptance criteria

• It is possible to enable Nova notification consumption in Watcher configuration file via watcher-operator
• It is possible to enable notification production in Watcher configuration file via watcher-operator

Documentation impact

For the time being when there's no OpenStackControlPlane level parameter to enable notification production and consumption we will need to document a proper way to enable Nova notification production via nova-operator and consumption of those via watcher-operator.