---
fixes:
  - |
    An instance can be rebuilt in-place with the original image or a new
    image. Instance resource usage cannot be altered during a rebuild.
    Previously Nova would have ignored the NUMA topology of the new image
    continuing to use the NUMA topology of the existing instance until a move
    operation was performed. As Nova did not explicitly guard against
    inadvertent changes in resource request contained in a new image,
    it was possible to rebuild with an image that would violate this requirement
    `bug #1763766`_. This resulted in an inconsistent state as the instance that
    was running did not match the instance that was requested. Nova now explicitly
    checks if a rebuild would alter the requested NUMA topology of an instance
    and rejects the rebuild.

    ..  _`bug #1763766`: https://bugs.launchpad.net/nova/+bug/1763766

features:
  - |
    With the changes introduced to address `bug #1763766`_, Nova now guards
    against NUMA constraint changes on rebuild. As a result the
    ``NUMATopologyFilter`` is no longer required to run on rebuild since
    we already know the topology will not change and therefor the existing
    resource claim is still valid. As such it is now possible to do an in-place
    rebuild of a instance with a NUMA topology even if the image changes
    provided the new image does not alter the topology.