Replace RPC cast() with notifications

Registered by Doug Hellmann on 2013-09-12

Ceilometer uses rpc.cast() calls internally to send sample data from the pipeline to the collector. We chose that route because we wanted to be able to scale the collector horizontally, and there was no way at the time to subscribe multiple consumers to notifications. Now that there is, we should switch to a notification format, to make it easier for third-party consumers of our sample data. The message payload shouldn't need to change substantially to make that work, and we can continue to publish the old RPC endpoint for now to make upgrades easier.

Blueprint information

Status:
Complete
Approver:
gordon chung
Priority:
Undefined
Drafter:
Doug Hellmann
Direction:
Approved
Assignee:
Mehdi Abaakouk
Definition:
Approved
Series goal:
Accepted for juno
Implementation:
Implemented
Milestone target:
milestone icon 2014.2
Started by
Julien Danjou on 2013-12-26
Completed by
Mehdi Abaakouk on 2014-10-27

Related branches

Sprints

Whiteboard

Gerrit topic: https://review.openstack.org/#q,topic:bp/replace-rpc-cast-with-notifications,n,z

Addressed by: https://review.openstack.org/77612
    Consume notif. from multiple message bus

Addressed by: https://review.openstack.org/77611
    Use NotificationPlugin as an oslo.msg endpoint

Addressed by: https://review.openstack.org/77845
    Use oslo.msg retry API in rpc publisher

Addressed by: https://review.openstack.org/80225
    Permit usage of notifications for metering

Addressed by: https://review.openstack.org/57457
    Replace oslo.rpc by oslo.messaging

Addressed by: https://review.openstack.org/112225
    Allow to requeue a sample

Addressed by: https://review.openstack.org/114919
    Document pipeline publishers configuration

(?)

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