Contrail Upgrade using Juju - Is there any potential risks to the Contrail agent on tenant compute nodes during and after the controller upgrade phase?
Juju contrail upgrade is ZIU (Zero Impact Upgrade). There are no potential risks to the Contrail agent on tenant compute nodes during and after the controller upgrade. This is because controller upgrade (bringing down and up of containers on controller) happens sequentially (one controller at a time) and this make sure at any point of time, compute will have XMPP connections to any two controllers. Also, for compute upgrades, to avoid downtime, before starting the upgrade on each compute, workloads can be migrated to another computes.