nova to neutron port notification fails in cells environment

[Liam Young]

When deploying OpenStack Icehouse on Ubuntu trusty in a cells configuration the callback from neutron to nova that notifies nova
when a port for an instance is ready to be used seems to be lost. This causes the spawning instance to go into an ERROR state and
the following int the nova-compute.log:

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 1714, in _spawn
    block_device_info)
  File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 2266, in spawn
    block_device_info)
  File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 3681, in _create_domain_and_network
    raise exception.VirtualInterfaceCreateException()
VirtualInterfaceCreateException: Virtual Interface creation failed

Adding "vif_plugging_is_fatal = False" and "vif_plugging_timeout = 5" to the compute nodes stops the missing message from being fatal and guests can then be spawned normally and accessed over the network.

This issue doesn't present itself when deploying in a non-cell configuration.

I'll attatch logs from attempting to spawn a new guest (at about 07:52) with:

nova boot --image precise --flavor m1.small --key_name test --nic net-id=b77ca278-6e00-4530-94fe-c946a6046acf server075238

where dc31c58f-e455-4a1a-b825-6777ccb8d3c1 is the resulting guest id

nova-cells 1:2014.1.1-0ubuntu1
nova-api-ec2 1:2014.1.1-0ubuntu1
nova-api-os-compute 1:2014.1.1-0ubuntu1
nova-cert 1:2014.1.1-0ubuntu1
nova-common 1:2014.1.1-0ubuntu1
nova-conductor 1:2014.1.1-0ubuntu1
nova-objectstore 1:2014.1.1-0ubuntu1
nova-scheduler 1:2014.1.1-0ubuntu1
neutron-common 1:2014.1.1-0ubuntu2
neutron-plugin-ml2 1:2014.1.1-0ubuntu2
neutron-server 1:2014.1.1-0ubuntu2
neutron-plugin-openvswitch-agent 1:2014.1.1-0ubuntu2
openvswitch-common 2.0.1+git20140120-0ubuntu2
openvswitch-switch 2.0.1+git20140120-0ubuntu2
neutron-plugin-ml2 1:2014.1.1-0ubuntu2

[Sean Dague (sdague)]

Low priority, cells is still experimental

[Markus Zoeller (markus_z) (mzoeller)]

This is an automated cleanup. This bug report has been closed because it
is older than 18 months and there is no open code change to fix this.
After this time it is unlikely that the circumstances which lead to
the observed issue can be reproduced.

If you can reproduce the bug, please:
* reopen the bug report (set to status "New")
* AND add the detailed steps to reproduce the issue (if applicable)
* AND leave a comment "CONFIRMED FOR: <RELEASE_NAME>"
  Only still supported release names are valid (LIBERTY, MITAKA, OCATA, NEWTON).
  Valid example: CONFIRMED FOR: LIBERTY