The libvirt driver power on and hard reboot destroys the domain first
and unplugs the vifs then recreate the domain and replug the vifs.
However nova does not wait for the network-vif-plugged event before
unpause the domain. This can cause that the domain starts running and
requesting IP via DHCP before the networking backend finished plugging
the vifs.
So this patch adds a workaround config option to nova to wait for
network-vif-plugged events during hard reboot the same way as nova waits
for this event during new instance spawn.
This logic cannot be enabled unconditionally as not all neutron
networking backend sending plug time events to wait for. Also the logic
needs to be vnic_type dependent as ml2/ovs and the in tree sriov backend
often deployed together on the same compute. While ml2/ovs sends plug
time event the sriov backend does not send it reliably. So the
configuration is not just a boolean flag but a list of vnic_types
instead. This way the waiting for the plug time event for a vif that is
handled by ml2/ovs is possible while the instance has other vifs handled
by the sriov backend where no event can be expected.
Change-Id: Ie904d1513b5cf76d6d5f6877545e8eb378dd5499
Closes-Bug: #1946729
68c970ea99