Nova fails to start if --start_guests_on_host_boot=true is set

[Adrian Moya]

Whith the following flags set on nova conf:

--start_guests_on_host_boot=true
--resume_guests_state_on_host_boot=true

When a compute node is hard rebooted (or in my case, suffer a power failure), nova-compute is unable to start on the node with the following error:

2012-06-09 11:24:16 INFO nova.virt.libvirt.connection [req-9c3628ce-f5c2-4f2c-9217-aed95ae10a42 None None] [instance: bea97c46-fde7-4fe8-8e89-ab8e81d635d5] Instance shutdown successfully.
2012-06-09 11:24:17 CRITICAL nova [-] Cannot get interface MTU on 'br100': No such device
2012-06-09 11:24:17 TRACE nova Traceback (most recent call last):
2012-06-09 11:24:17 TRACE nova File "/usr/bin/nova-compute", line 49, in <module>
2012-06-09 11:24:17 TRACE nova service.wait()
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/service.py", line 413, in wait
2012-06-09 11:24:17 TRACE nova _launcher.wait()
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/service.py", line 131, in wait
2012-06-09 11:24:17 TRACE nova service.wait()
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/eventlet/greenthread.py", line 166, in wait
2012-06-09 11:24:17 TRACE nova return self._exit_event.wait()
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/eventlet/event.py", line 116, in wait
2012-06-09 11:24:17 TRACE nova return hubs.get_hub().switch()
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/eventlet/hubs/hub.py", line 177, in switch
2012-06-09 11:24:17 TRACE nova return self.greenlet.switch()
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/eventlet/greenthread.py", line 192, in main
2012-06-09 11:24:17 TRACE nova result = function(*args, **kwargs)
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/service.py", line 101, in run_server
2012-06-09 11:24:17 TRACE nova server.start()
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/service.py", line 162, in start
2012-06-09 11:24:17 TRACE nova self.manager.init_host()
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 247, in init_host
2012-06-09 11:24:17 TRACE nova self.reboot_instance(context, instance['uuid'])
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/exception.py", line 114, in wrapped
2012-06-09 11:24:17 TRACE nova return f(*args, **kw)
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 153, in decorated_function
2012-06-09 11:24:17 TRACE nova function(self, context, instance_uuid, *args, **kwargs)
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 177, in decorated_function
2012-06-09 11:24:17 TRACE nova sys.exc_info())
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/contextlib.py", line 24, in __exit__
2012-06-09 11:24:17 TRACE nova self.gen.next()
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 171, in decorated_function
2012-06-09 11:24:17 TRACE nova return function(self, context, instance_uuid, *args, **kwargs)
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 898, in reboot_instance
2012-06-09 11:24:17 TRACE nova reboot_type)
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/exception.py", line 114, in wrapped
2012-06-09 11:24:17 TRACE nova return f(*args, **kw)
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/connection.py", line 718, in reboot
2012-06-09 11:24:17 TRACE nova if self._soft_reboot(instance):
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/connection.py", line 754, in _soft_reboot
2012-06-09 11:24:17 TRACE nova dom.create()
2012-06-09 11:24:17 TRACE nova File "/usr/lib/python2.7/dist-packages/libvirt.py", line 551, in create
2012-06-09 11:24:17 TRACE nova if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
2012-06-09 11:24:17 TRACE nova libvirtError: Cannot get interface MTU on 'br100': No such device

It seems that nova-compute doesn't create the bridge and thus fails to start. Removing both settings from nova conf makes nova-compute start again.

[Vish Ishaya (vishvananda)]

This was recently changed in trunk. I think this is fixed now.

[Vish Ishaya (vishvananda)]

fix is here: https://review.openstack.org/#/c/8035/

It should probably be backported to essex

[Vish Ishaya (vishvananda)]

stable/essex here: https://review.openstack.org/#/c/8423/