Merge "Switch Trove to use OSLO Messaging."

specs/kilo/switch-to-oslo-messaging.rst

@@ -0,0 +1,126 @@
+..
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+ Sections of this template were taken directly from the Nova spec
+ template at:
+ https://github.com/openstack/nova-specs/blob/master/specs/template.rst
+..
+
+========================
+Switch to OSLO Messaging
+========================
+
+Include the URL of your launchpad blueprint:
+
+https://wiki.openstack.org/wiki/Trove-rpc-versioning
+
+This blueprint is to document the project to switch trove to use OSLO
+Messaging.
+
+Problem description
+===================
+
+Get Trove on the same page w/ other projects + oslo. This will require
+refactoring the rpc layer
+
+Prevent backward incompatibility between Trove components
+
+* The rpc client can send an older version of a message/call to a newer message handler without issue.
+* The rpc client can send a newer version of a message/call to an older message handler without killing it (need to confirm this).
+* The rpc client can check to see if it can send a newer version of a message/call.
+
+* Reduce the need for downtime during deployments.
+
+** Effectively allows for a mix of versions between the control plane and guest agents (in most cases). There may still be updates that will require down time.
+
+Proposed change
+===============
+
+* Remove rpc common components from oslo incubator?
+* Use oslo messaging library
+
+** The minimum version will be picked from global-requirements. At the time of this writing, it's >= 1.4.0
+
+*  Keep track of a "version history" in comments in the code
+
+* Update trove calls to the openstack.common.rpc client to include a version cap param. (This is already supported in the client)
+
+** Trove API    --> Task Manager
+** Trove API    --> Guest Agent
+** Guest Agent  --> Conductor
+** Task Manager --> Conductor
+** Document the use cases and examples of how to add/modify API calls
+
+
+Configuration
+-------------
+
+oslo.messaging has been designed to be backwards compatible config-wise. All the config compatibilities will be kept until all the projects have been migrated to oslo.messaging.
+
+Database
+--------
+
+NA
+
+Public API
+----------
+
+NA
+
+Internal API
+------------
+
+NA
+
+Guest Agent
+-----------
+
+NA
+
+
+Alternatives
+------------
+
+None
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+   sgotliv
+
+Milestones
+----------
+
+Kilo-1
+
+Work Items
+----------
+
+* see above.
+
+Dependencies
+============
+
+None
+
+Testing
+=======
+
+Additional tests will be proposed if required, existing tests amended.
+
+Documentation Impact
+====================
+
+Yes
+
+References
+==========
+
+See https://review.openstack.org/#/c/94484/