openstack/neutron
Code Issues Proposed changes

Merge "devref: added more details on rolling upgrade for notifications"

Browse Source
This commit is contained in:
Jenkins 2016-02-05 14:05:12 +00:00 committed by Gerrit Code Review
commit c06130e6dd
1 changed files with 19 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
doc/source/devref/upgrade.rst
View File

@ -140,6 +140,23 @@ agents, only the former should handle both old and new RPC versions.
The implication of that is that no code that handles UnsupportedVersion The implication of that is that no code that handles UnsupportedVersion
oslo.messaging exceptions belongs to agent code. oslo.messaging exceptions belongs to agent code.
Notifications
'''''''''''''
For notifications that are issued by neutron-server to listening agents,
special consideration is needed to support rolling upgrades. In this case, a
newer controller sends newer payload to older agents.
Until we have proper RPC version pinning feature to enforce older payload
format during upgrade (as it's implemented in other projects like nova), we
leave our agents resistant against unknown arguments sent as part of server
notifications. This is achieved by consistently capturing those unknown
arguments with keyword arguments and ignoring them on agent side; and by not
enforcing newer RPC entry point versions on server side.
This approach is not ideal, because it makes RPC API less strict. That's why
other approaches should be considered for notifications in the future.
:ref:`More information about RPC versioning <rpc_versioning>`. :ref:`More information about RPC versioning <rpc_versioning>`.
Interface signature Interface signature
@ -247,6 +264,8 @@ Now to specifics:
that server should be able to handle old requests, without the new that server should be able to handle old requests, without the new
argument specified. Also, if the argument is not passed, the old behaviour argument specified. Also, if the argument is not passed, the old behaviour
before the addition of the argument should be retained. before the addition of the argument should be retained.
* minimal client version must not be bumped for server initiated
notification changes for at least one cycle.
#. Database migrations: #. Database migrations: