Disable NUMATopologyFilter on rebuild

This change leverages the new NUMA constraint checking added in
in I0322d872bdff68936033a6f5a54e8296a6fb3434 to allow the
NUMATopologyFilter to be skipped on rebuild.

As the new behavior of rebuild enfroces that no changes
to the numa constraints are allowed on rebuild we no longer
need to execute the NUMATopologyFilter. Previously
the NUMATopologyFilter would process the rebuild request
as if it was a request to spawn a new instnace as the
numa_fit_instance_to_host function is not rebuild aware.

As such prior to this change a rebuild would only succeed
if a host had enough additional capacity for a second instance
on the same host meeting the requirement of the new image and
existing flavor. This behavior was incorrect on two counts as
a rebuild uses a noop claim. First the resouce usage cannot
change so it was incorrect to require the addtional capacity
to rebuild an instance. Secondly it was incorrect not to assert
the resouce usage remained the same.

I0322d872bdff68936033a6f5a54e8296a6fb3434 adressed guarding the
rebuild against altering the resouce usage and this change
allows in place rebuild.

This change found a latent bug that will be adressed in a follow
up change and updated the functional tests to note the incorrect
behavior.

Change-Id: I48bccc4b9adcac3c7a3e42769c11fdeb8f6fd132
Closes-Bug: #1804502
Implements: blueprint inplace-rebuild-of-numa-instances

1 files changed, 5 insertions, 1 deletions

diff --git a/nova/scheduler/filters/numa_topology_filter.py b/nova/scheduler/filters/numa_topology_filter.py
index 9b90363718..fae8a45600 100644
--- a/nova/scheduler/filters/numa_topology_filter.py
+++ b/nova/scheduler/filters/numa_topology_filter.py
@@ -23,7 +23,11 @@ LOG = logging.getLogger(__name__)
 class NUMATopologyFilter(filters.BaseHostFilter):
     """Filter on requested NUMA topology."""
 
-    RUN_ON_REBUILD = True
+    # NOTE(sean-k-mooney): In change I0322d872bdff68936033a6f5a54e8296a6fb343
+    # we validate that the NUMA topology does not change in the api. If the
+    # requested image would alter the NUMA constrains we reject the rebuild
+    # request and therefore do not need to run this filter on rebuild.
+    RUN_ON_REBUILD = False
 
     def _satisfies_cpu_policy(self, host_state, extra_specs, image_props):
         """Check that the host_state provided satisfies any available