Comment 22 for bug 1597596

I've still not found a proper way to fix this, but I would like to share the attached patch that will allow to easily reproduce the issue on a simple devstack node. It consists of three parts:

1. Patch nova/virt/libvirt/driver.py to insert a single error when spawning an instance. This will trigger a Reschedule and let spawning succeed on the second attempt.
2. Patch nova/scheduler/utils.py so that the Reschedule may happen on the same host again. The default behaviour will exclude the hosts where the instance has been scheduled first, which would imply that one needs a multi-node setup in order to reproduce this issue.
3. Add some debugging output to nova/compute/manager.py

The first instance booted after applying this patch (and restarting n-cond & n-cpu) will be running fine but with two addresses allocated.

It looks to me like the first address is generated properly in the n-cpu manager, but is then treated correctly in the conductor during rescheduling.