Service create and destroy versioned notification

Service create and destroy versioned notification

https://blueprints.launchpad.net/nova/+spec/service-create-destroy-notification

External system can get versioned notification [1] for service update based information. But not for service create and destroy action.

Adding notifications for create and destroy help the external system to get the realtime status for service without callback to the nova API.

Problem description

Use Cases

The external notification consumer like Searchlight wants to get the services information when service created, updated or destroyed.

Proposed change

Send notification for Service.create and Service.destroy as well as Service.save [2].

Alternatives

The only alternative is to poll /v2/{tenant_id}/os-services/ API periodically however it means slower information flow and creates load on the nova API and DB services.

Data model impact

No database schema change is foreseen.

uuid field will need be added to ServiceStatusPayload for external system to query the right service for updating or destroying, and make the data consistent with new os-services API [3].

@base.NovaObjectRegistry.register
class ServiceStatusPayload(base.NovaObject):
    SCHEMA = {
        'id': ('service', 'id'),
        'host': ('service', 'host'),
        'binary': ('service', 'binary'),
        'topic': ('service', 'topic'),
        'report_count': ('service', 'report_count'),
        'disabled': ('service', 'disabled'),
        'disabled_reason': ('service', 'disabled_reason'),
        'availability_zone': ('service', 'availability_zone'),
        'last_seen_up': ('service', 'last_seen_up'),
        'forced_down': ('service', 'forced_down'),
        'version': ('service', 'version')
    }
    # Version 1.0: Initial version
    # Version 1.1: Added id field
    VERSION = '1.1'
    fields = {
        'id': fields.UUIDField(),
        'host': fields.StringField(nullable=True),
        'binary': fields.StringField(nullable=True),
        'topic': fields.StringField(nullable=True),
        'report_count': fields.IntegerField(),
        'disabled': fields.BooleanField(),
        'disabled_reason': fields.StringField(nullable=True),
        'availability_zone': fields.StringField(nullable=True),
        'last_seen_up': fields.DateTimeField(nullable=True),
        'forced_down': fields.BooleanField(),
        'version': fields.IntegerField(),
    }

    def __init__(self, service):
        super(ServiceStatusPayload, self).__init__()
        self.populate_schema(service=service)

REST API impact

None

Security impact

None

Notifications impact

New notifications service.create and service.delete will be introduced with INFO priority and the payload of the notification will be the serialized form of the already existing Service versioned object. Service.create notification will be emitted after the service is created (so the id is available) and also send the service.delete notification after the service is deleted.

Other end user impact

None

Performance Impact

None

Other deployer impact

None

Developer impact

None

Implementation

Assignee(s)

Primary assignee:

liyingjun

Work Items

  • Send version notifications for service.create and service.delete.

Dependencies

None

Testing

Besides unit test new functional test cases will be added to cover the new notifications

Documentation Impact

None

History

Revisions

Release Name

Description

Queens

Introduced

Creative Commons Attribution 3.0 License

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nova-specs