The goal of this patch is to avoid the connection disruption during
the live-migration using OVS. Since [1], when a port is migrated,
both the source and the destination hosts are added to the profile
binding information. Initially, the source host binding is activated
and the destination is deactivated.
When the port is created in the destination host (created by Nova),
the port was not configured because the binding was not activated.
The binding (that means, all the OpenFlow rules) was done when Nova
sent the port activation. That happend when the VM was already
running in the destination host. If the OVS agent was loaded, the
port was bound seconds later to the port activation.
Instead, this patch enables the OpenFlow rule creation in the
destination host when the port is created.
Another problem are the "neutron-vif-plugged" events sent by Neutron
to Nova to inform about the port binding. Nova is expecting one single
event informing about the destination port binding. At this moment,
Nova considers the port is bound and ready to transmit data.
Several triggers were firing expectedly this event:
- When the port binding was updated, the port is set to down and then
up again, forcing this event.
- When the port binding was updated, first the binding is deleted and
then updated with the new information. That triggers in the source
host to set the port down and the up again, sending the event.
This patch removes those events, sending the "neutron-vif-plugged"
event only when the port is bound to the destination host (and as
commented before, this is happening now regardless of the binding
activation status).
This feature depends on [2]. If this Nova patch is not in place, Nova
will never plug the port in the destination host and Neutron won't be
able to send the vif-plugged event to Nova to finish the
live-migration process.
Because from Neutron cannot query Nova to know if this patch is in
place, a new temporary configuration option has been created to enable
this feature. The default value will be "False"; that means Neutron
will behave as before.
[1]https://bugs.launchpad.net/neutron/+bug/1580880
[2]https://review.opendev.org/c/openstack/nova/+/767368
Closes-Bug: #1901707
Change-Id: Iee323943ac66e566e5a5e92de1861832e86fc7fc
f8a22c7d4a