Wrong image ref after unshelve

[Lucian Petrut]

After an instance is unshelved, the instance image ref will point to the original image instead of the snapshot created during the shelving [1][2].

Subsequent instance operations will use the wrong image id. For example, in case of cold migrations, Hyper-V instances will be unable to boot since the differencing images will have the wrong base [3]. Other image related operations might be affected as well.

As pointed out by Matt Riedemann on the patch [1], Nova shouldn't set back the original image id, instead it should use the snapshot id.

[1] I3bba0a230044613e07122a6d122597e5b8d43438
[2] https://github.com/openstack/nova/blob/22.0.1/nova/compute/manager.py#L6625
[3] http://paste.openstack.org/raw/800822/

[Lucian Petrut (petrutlucian94)]

Fix: https://review.opendev.org/c/openstack/nova/+/765924

[Stephen Finucane (stephenfinucane)]

Moving this to invalid based on the comments from Lucian on [1]

  I think this should be fixed at the Hyper-V driver level. The stashed image will be removed
  from Glance once the instance is unstashed, so there's no value in updating the Nova
  instance db record to point to it. In fact, users are probably interested in the original
  image.

[1] https://review.opendev.org/c/openstack/nova/+/765924

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/compute-hyperv 12.0.0.0rc1 release candidate.