I cannot see how this bug is Urgent, given that OVN has only supported node-before-controller since the beginning. That's not a regression.

If there is some functionality that broke unexpectedly within the supported model above, then *that* could potentially be an urgent fix.

Updating the summary to indicate that this is an investigative task rather than an implementation one. The OVN team will do investigation and come up with more concrete smaller subtasks to perform to reach this goal, assuming that the investigation finds that this sort of upgrade is feasible.

(In reply to Dan Williams from comment #4)
> I cannot see how this bug is Urgent, given that OVN has only supported
> node-before-controller since the beginning. That's not a regression.

Then this was very poorly communicated, for instance RHV team for years of support of OVN never defined any upgrade order, the order is flexible and RHV is routinely upgraded with controller first.

(In reply to Michal Skrivanek from comment #6)
> (In reply to Dan Williams from comment #4)
> > I cannot see how this bug is Urgent, given that OVN has only supported
> > node-before-controller since the beginning. That's not a regression.
> 
> Then this was very poorly communicated, for instance RHV team for years of
> support of OVN never defined any upgrade order, the order is flexible and
> RHV is routinely upgraded with controller first.

Likely could be better communicated, yes.

Though the OVN upgrade documentation here:

https://docs.ovn.org/en/latest/intro/install/ovn-upgrades.html
(sourced from https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/ovn-upgrades.rst)

hasn't changed in ~6 years and it's pretty clear about upgrading controllers first.