On Mon, Aug 4, 2025 at 4:15 PM Dan Smith <dms@danplanet.com> wrote:
How does Nova relate to having unmanaged libvirt VMs alongside VMs managed by nova-compute? Is this considered supported, unsupported, or somewhere in between?
Unrelated to stable-compute-uuid, we do not support this at all, in any way. Nova expects (and has always expected) to be the only thing managing the VMs on a libvirt instance, full stop.
I think this is an example of nova never intended to support the collocation of VMs but never prevented either. And therefore users out there started to rely on this capability. Now we started breaking that capability with the compute_uuid change. But we don't necessarily need to break it with that change. We could have both the compute_uuid change verifying that no nova VMs are running on the host and therefore preventing host rename, and still keeping the old behavior of allowing non nova VMs to run on the host. We would simply need to explicitly check the VMs reported by libvirt if they have nova metadata or not. I'm not sure what we would lose with this simple change. gibi
--Dan