Comment 0 for bug 1723480

Similar to, but slightly different from bug 1712444, we have found the upgrade of the openvswitch-switch package by unattended-upgrade (or otherwise) will trigger the service restart of openvswitch-switch within the neutron-openvswitch charm if the config-changed hook is called.

While this is a reasonable behavior based on an assumption that if the /etc/default/openvswitch-switch file changes due to upgrade and the charm resets it to the charm-configured version of the file, we should want to restart the service to be on the latest code. However, the restart of the service causes between 6-12 seconds of network outage for the tenant VMs utilizing OVS.

Would it be possible to have a config-flag to disable the charm's ability to restart the openvswitch-switch service outside of the install hook to avoid automated network outages due to package upgrades?

Elsewise, is there a way to serialize the resulting restarts in such a way that only one member of the neutron-openvswitch application/service is restarting at a time along with a buffer to allow for high availability applications to failover and fail back and not be afflicted by multiple nodes' switches being restarted simultaneously.