need to check if a plugin's start rpc listeners is supported before trying to start it

[Brandon Logan]

This showed up on a new service plugin being created that did not need to start rpc workers. It did not implement the start_rpc_listeners method so the base class has it raise NotImplemented.

The neutron.service.RpcWorker.start method should check if the plugin supports it by using the plugin.rpc_workers_supported method.

https://github.com/openstack/neutron/blob/master/neutron/neutron_plugin_base_v2.py#L389-L402

    2016-03-01 11:35:19.983 ERROR oslo_service.service [-] Error starting thread.
    2016-03-01 11:35:19.983 TRACE oslo_service.service Traceback (most recent call last):
    2016-03-01 11:35:19.983 TRACE oslo_service.service File "/usr/local/lib/python2.7/dist-packages/oslo_service/service.py", line 680, in run_service
    2016-03-01 11:35:19.983 TRACE oslo_service.service service.start()
    2016-03-01 11:35:19.983 TRACE oslo_service.service File "/opt/stack/neutron/neutron/service.py", line 142, in start
    2016-03-01 11:35:19.983 TRACE oslo_service.service servers = getattr(plugin, self.start_listeners_method)()
    2016-03-01 11:35:19.983 TRACE oslo_service.service File "/opt/stack/neutron/neutron/neutron_plugin_base_v2.py", line 377, in start_rpc_listeners
    2016-03-01 11:35:19.983 TRACE oslo_service.service raise NotImplementedError()
    2016-03-01 11:35:19.983 TRACE oslo_service.service NotImplementedError
    2016-03-01 11:35:19.983 TRACE oslo_service.service

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/286384

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/286384
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=cd7be292a8d1fb4ce913c4e7fbfc55fda033ffbe
Submitter: Jenkins
Branch: master

commit cd7be292a8d1fb4ce913c4e7fbfc55fda033ffbe
Author: Brandon Logan <email address hidden>
Date: Mon Feb 29 23:11:18 2016 -0600

    Check if plugin supports starting rpc listeners

    When neutron starts an rpc worker, it checks if the plugin has the method
    "start_rpc_listeners". Since most plugins inherit from a base class, and
    that base class implements the start_rpc_listeners method and raises
    NotImplementedError, the rpc worker will attempt to call that method.
    It should just catch the NotImplementedError and continue on.

    Change-Id: Ie1830b6140acffffd0f283a0d8eefa52067f7650
    Closes-Bug: 1551542

[Thierry Carrez (ttx)]

This issue was fixed in the openstack/neutron 8.0.0.0rc1 release candidate.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/238745
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=de5bdc9cc2cde9100802d68309fa6dfe3ef31f4d
Submitter: Jenkins
Branch: stable/liberty

commit de5bdc9cc2cde9100802d68309fa6dfe3ef31f4d
Author: Eugene Nikanorov <email address hidden>
Date: Wed Sep 23 14:06:54 2015 +0400

    Consume service plugins queues in RPC workers.

    This patch adds all RPC workers to consumers of service
    plugins queues such as metering and l3-plugin.
    This is important for DVR-enabled deployments with hundreds
    of agents.

    Closes-Bug: #1498844
    (cherry picked from commit 5be613490deebf494f2ecbbcd8cb5dd0d6f5e1b3)

    ===

    Also include the following fix that keeps backwards compatibility with
    plugins that don't implement start_rpc_listeners method:

    Check if plugin supports starting rpc listeners

    When neutron starts an rpc worker, it checks if the plugin has the method
    "start_rpc_listeners". Since most plugins inherit from a base class, and
    that base class implements the start_rpc_listeners method and raises
    NotImplementedError, the rpc worker will attempt to call that method.
    It should just catch the NotImplementedError and continue on.

    Change-Id: Ie1830b6140acffffd0f283a0d8eefa52067f7650
    Closes-Bug: 1551542
    (cherry picked from commit cd7be292a8d1fb4ce913c4e7fbfc55fda033ffbe)

    ===

    Change-Id: I6fea7f409c91b25d2c35b038d6100fdfa85d1905

[Thierry Carrez (ttx)]

This issue was fixed in the openstack/neutron 7.1.0 release.