scheduler rpcapi 2.9 is not backwards compatible

[Nikola Đipanov]

patch 552693e4ad51291c8bfd28cd1939ed3609f6eeac (https://review.openstack.org/#/c/37933/) which added compute scheduler rpcapi version 2.9 does not provide any backwards compatibility, this should be done using 'self.can_send_version'

The result of this is, if compute is running grizzly and trunk is running with

[upgrade_levels]
scheduler=grizzly

in nova.conf

nova-conductor logs:
1e5a084a4838b5d258532645eacc'} from (pid=861) _safe_log /opt/stack/nova/nova/openstack/common/rpc/common.py:277
2013-09-03 04:32:36.347 DEBUG qpid.messaging.io.ops [-] SENT[4a35cb0]: SessionCompleted(commands=[0-16]) from (pid=861) write_op /usr/lib/python2.7/site-packages/qpid/messaging/driver.py:671
2013-09-03 04:32:36.351 ERROR nova.openstack.common.rpc.amqp [req-b596a82a-0be1-4b90-a93a-d05ae7011e0b demo demo] Exception during message handling
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp Traceback (most recent call last):
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp File "/opt/stack/nova/nova/openstack/common/rpc/amqp.py", line 461, in _process_data
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp **args)
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp File "/opt/stack/nova/nova/openstack/common/rpc/dispatcher.py", line 172, in dispatch
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp result = getattr(proxyobj, method)(ctxt, **kwargs)
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp File "/opt/stack/nova/nova/conductor/manager.py", line 745, in build_instances
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp legacy_bdm_in_spec=legacy_bdm)
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp File "/opt/stack/nova/nova/scheduler/rpcapi.py", line 112, in run_instance
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp legacy_bdm_in_spec=legacy_bdm_in_spec), version='2.9')
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp File "/opt/stack/nova/nova/openstack/common/rpc/proxy.py", line 169, in cast
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp self._set_version(msg, version)
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp File "/opt/stack/nova/nova/openstack/common/rpc/proxy.py", line 72, in _set_version
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp raise rpc_common.RpcVersionCapError(version_cap=self.version_cap)
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp RpcVersionCapError: Specified RPC version cap, 2.6, is too low
2013-09-03 04:32:36.351 TRACE nova.openstack.common.rpc.amqp

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/44839

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/44839
Committed: http://github.com/openstack/nova/commit/035f05eb531cb8dd805685272d46ecd8cb0ad2b3
Submitter: Jenkins
Branch: master

commit 035f05eb531cb8dd805685272d46ecd8cb0ad2b3
Author: Nikola Dipanov <email address hidden>
Date: Tue Sep 3 11:08:39 2013 +0200

    Scheduler rpcapi 2.9 is not backwards compatible

    Patch 552693e4ad51291c8bfd28cd1939ed3609f6eeac which added scheduler
    rpcapi version 2.9 does not provide any backwards compatibility.

    This patch adds the check using 'self.can_send_version', and falls
    back to the latest Grizzly compatible version if it the version is
    capped.

    Also takes the opportunity to make the docstring more consistent in the
    scheduler rpcapi SchedulerAPI class.

    Closes-bug: #1220112

    Change-Id: I5a1e08c1066cae00d47def45f7b87846f679cbbe