get_vnc_console returns 500 error if called before host is assigned

[Johannes Erdfelt]

There exists a window between a server create is done and when the host is assigned by the scheduler that a request to get the vnc console will result in a 500 error.

An exception similar to this will be seen in the logs:

2012-08-16 21:42:43 TRACE nova.api.openstack Traceback (most recent call last):
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/openstack/nova/trunk/nova/api/openstack/__init__.py", line 78, in __call__
2012-08-16 21:42:43 TRACE nova.api.openstack return req.get_response(self.application)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/virtualenvs/nova/lib/python2.6/site-packages/webob/request.py", line 1053, in get_response
2012-08-16 21:42:43 TRACE nova.api.openstack application, catch_exc_info=False)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/virtualenvs/nova/lib/python2.6/site-packages/webob/request.py", line 1022, in call_application
2012-08-16 21:42:43 TRACE nova.api.openstack app_iter = application(self.environ, start_response)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/virtualenvs/nova/lib/python2.6/site-packages/webob/dec.py", line 159, in __call__
2012-08-16 21:42:43 TRACE nova.api.openstack return resp(environ, start_response)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/virtualenvs/nova/lib/python2.6/site-packages/keystone-2012.2-py2.6.egg/keystone/middleware/auth_token.py", line 213, in __call__
2012-08-16 21:42:43 TRACE nova.api.openstack return self.app(env, start_response)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/virtualenvs/nova/lib/python2.6/site-packages/webob/dec.py", line 159, in __call__
2012-08-16 21:42:43 TRACE nova.api.openstack return resp(environ, start_response)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/virtualenvs/nova/lib/python2.6/site-packages/webob/dec.py", line 159, in __call__
2012-08-16 21:42:43 TRACE nova.api.openstack return resp(environ, start_response)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/virtualenvs/nova/lib/python2.6/site-packages/Routes-1.13-py2.6.egg/routes/middleware.py", line 131, in __call__
2012-08-16 21:42:43 TRACE nova.api.openstack response = self.app(environ, start_response)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/virtualenvs/nova/lib/python2.6/site-packages/webob/dec.py", line 159, in __call__
2012-08-16 21:42:43 TRACE nova.api.openstack return resp(environ, start_response)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/virtualenvs/nova/lib/python2.6/site-packages/webob/dec.py", line 147, in __call__
2012-08-16 21:42:43 TRACE nova.api.openstack resp = self.call_func(req, *args, **self.kwargs)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/virtualenvs/nova/lib/python2.6/site-packages/webob/dec.py", line 208, in call_func
2012-08-16 21:42:43 TRACE nova.api.openstack return self.func(req, *args, **kwargs)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/openstack/nova/trunk/nova/api/openstack/wsgi.py", line 864, in __call__
2012-08-16 21:42:43 TRACE nova.api.openstack content_type, body, accept)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/openstack/nova/trunk/nova/api/openstack/wsgi.py", line 912, in _process_stack
2012-08-16 21:42:43 TRACE nova.api.openstack action_result = self.dispatch(meth, request, action_args)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/openstack/nova/trunk/nova/api/openstack/wsgi.py", line 1000, in dispatch
2012-08-16 21:42:43 TRACE nova.api.openstack return method(req=request, **action_args)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/openstack/nova/trunk/nova/api/openstack/compute/contrib/consoles.py", line 48, in get_vnc_console
2012-08-16 21:42:43 TRACE nova.api.openstack console_type)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/openstack/nova/trunk/nova/compute/api.py", line 120, in wrapped
2012-08-16 21:42:43 TRACE nova.api.openstack return func(self, context, target, *args, **kwargs)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/openstack/nova/trunk/nova/compute/api.py", line 1631, in get_vnc_console
2012-08-16 21:42:43 TRACE nova.api.openstack instance=instance, console_type=console_type)
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/openstack/nova/trunk/nova/compute/rpcapi.py", line 254, in get_vnc_console
2012-08-16 21:42:43 TRACE nova.api.openstack topic=_compute_topic(self.topic, ctxt, None, instance),
2012-08-16 21:42:43 TRACE nova.api.openstack File "/home/johannes/openstack/nova/trunk/nova/compute/rpcapi.py", line 48, in _compute_topic
2012-08-16 21:42:43 TRACE nova.api.openstack 'Instance %s') % instance['uuid'])
2012-08-16 21:42:43 TRACE nova.api.openstack NovaException: Unable to find host for Instance 1a3f3a81-fd2f-4a99-b446-5e03216fe045

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/11574

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/11574
Committed: http://github.com/openstack/nova/commit/fa16d173938b30af4e1cc6b312a75b12aff6c424
Submitter: Jenkins
Branch: master

commit fa16d173938b30af4e1cc6b312a75b12aff6c424
Author: Russell Bryant <email address hidden>
Date: Fri Aug 17 15:21:36 2012 -0400

    Fix get_vnc_console race.

    There exists a window between a server create is done and when the host
    is assigned by the scheduler that a request to get the vnc console will
    result in a 500 error.

    This patch adds a check in the compute API to ensure that the instance
    has a host assigned before try to execute a rpc on the compute node.
    If not, it raises InstanceNotReady (which translates to a 409 in the
    OS API).

    Fix bug 1037809.

    Change-Id: I3f5af90d57ae84f98f787e14ccb66f1841ac0c6d