conductor: Cross-HV resize preflight checks by grandchild · Pull Request #625 · sapcc/nova

grandchild · 2026-06-01T15:33:31Z

We allow it only if it's:

a BFV instance, that
is powered on.
And only from VMware to CH, not backwards.

The image properties are now sanitized and saved, only on vmware->ch hv transition, inside the new _prep_cross_hv_resize() step.

Sanitize VMware-specific image properties directly on the canonical RequestSpec before scheduling, matching how request_spec.flavor is already handled in the cold migrate flow. The sanitizer mutates request_spec.image.properties in place and returns a dict of original values. After task.execute() succeeds, the conductor persists this into MigrationContext.old_image_properties (via instance.save()) before calling request_spec.save(). This ordering ensures the rollback copy is always available if request_spec has been rewritten. Changes: - nova/compute/utils.py: add sanitize_image_props_for_kvm() - nova/conductor/tasks/migrate.py: call sanitizer in _execute() - nova/conductor/manager.py: persist old_image_properties to MigrationContext before request_spec.save() Change-Id: I4f7035358a9a7f46d942bfad07d748d1d333f8c5

anokfireball · 2026-06-02T13:55:03Z

+            self.context, self.instance.uuid)
+        volume_ids = {bdm.volume_id for bdm in bdms if bdm.volume_id}
+        if volume_ids:
+            snapshots = volume_api.get_all_snapshots(self.context)


This iterates through all the snapshots of a project as far as I can tell. Is there maybe a way to filter for the volume id below at the cinder API level already?

https://docs.openstack.org/api-ref/block-storage/v3/index.html#volume-snapshots-snapshots
doesn't look like it :/

anokfireball · 2026-06-02T13:59:51Z

+            self.context, self.instance.uuid)
+        volume_ids = {bdm.volume_id for bdm in bdms if bdm.volume_id}
+        if volume_ids:
+            snapshots = volume_api.get_all_snapshots(self.context)


I know it is still specified in the ticket to have this snapshot check. But since we are not doing volume retyping for BFV during the resize (anymore), it's probably not required (anymore).

hm, right... I'll remove it altogether.

grandchild · 2026-06-03T19:46:56Z

Added unit tests.
Removed volume snapshots check, which removed a few hunks altogether, since the volume_api doesn't need to be passed through anymore now.

We allow it only if it's: - a BFV instance, that - is powered on. And only from VMware to CH, not backwards. The image properties are now sanitized and saved, only on vmware->ch hv transition, inside the new _prep_cross_hv_resize() step. Change-Id: I50dedca220e70f51811c0f9b9327ca3ae7ea9e12

grandchild · 2026-06-05T14:07:55Z

Integrated on top of #623 .

anokfireball · 2026-06-08T09:20:27Z

+                and extra_specs_ops.match("CH", dest_hv):
+            if not self.request_spec.is_bfv:
+                raise exception.InvalidCrossHvResizePrecondition(
+                    'Must be BFV instance')


Suggested change

'Must be BFV instance')

reason='Must be BFV instance')

anokfireball · 2026-06-08T09:21:11Z

+                    'Must be BFV instance')
+            if self.instance.power_state != power_state.RUNNING:
+                raise exception.InvalidCrossHvResizePrecondition(
+                    'Instance must be running for cross-hypervisor resize. '


Suggested change

'Instance must be running for cross-hypervisor resize. '

reason='Instance must be running for cross-hypervisor resize. '

anokfireball · 2026-06-08T09:24:53Z

+    msg_fmt = _('Resize from hypervisor type %(src_hv_type)s to '
+                '%(dest_hv_type)s is not allowed')
+
+class InvalidCrossHvResizePrecondition(NovaException):


Suggested change

class InvalidCrossHvResizePrecondition(NovaException):

class InvalidCrossHvResizePrecondition(NovaException):

to make PEP8 happy I guess.

anokfireball · 2026-06-08T09:30:30Z

-                    self.request_spec))
+        src_hv = self._source_cn.hypervisor_type
+        dest_hv = self.flavor.extra_specs.get('capabilities:hypervisor_type')
+        if dest_hv and not extra_specs_ops.match(src_hv, dest_hv):


There's no test where dest_hv is set but is identical to src_hv (so both are VMware or both CH). It think it would be nice to have a test that we don't break the existing same-HV resize flow: It should confirm that _prep_cross_hv_resize is not called when source and destination are same-HV.

anokfireball · 2026-06-08T09:32:22Z

+                exception.InvalidCrossHvResizePrecondition) as ex:
+            vm_state = instance.vm_state
+            if not vm_state:
+                vm_state = vm_states.ACTIVE


Adding a test for this branch would also be nice: Verify the instance state is properly restored (not set to ERROR) when the exception fires and resets to the ACTIVE fallback.

anokfireball · 2026-06-08T09:33:39Z

-            self._old_image_properties = (
-                compute_utils.sanitize_image_props_for_kvm(
-                    self.request_spec))
+        src_hv = self._source_cn.hypervisor_type


Could src_hv somehow also be None? It's properly handled for dest_hv below, just feels like we could do the same for src_hv?

grandchild changed the base branch from stable/2023.2-m3 to cross-hv-reqspec-early-commit June 1, 2026 15:35

grandchild marked this pull request as ready for review June 1, 2026 15:35

grandchild marked this pull request as draft June 1, 2026 15:36

grandchild force-pushed the crosshv_resize_detection branch 2 times, most recently from 91eb9fa to 41d1d06 Compare June 2, 2026 08:44

anokfireball reviewed Jun 2, 2026

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Comment thread nova/tests/unit/conductor/tasks/test_migrate.py Outdated

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grandchild force-pushed the crosshv_resize_detection branch 3 times, most recently from 251f927 to 4116348 Compare June 3, 2026 19:46

grandchild force-pushed the crosshv_resize_detection branch from 4116348 to 78d8199 Compare June 3, 2026 19:56

grandchild force-pushed the crosshv_resize_detection branch from 78d8199 to 72706db Compare June 4, 2026 12:52

grandchild marked this pull request as ready for review June 5, 2026 14:08

anokfireball reviewed Jun 8, 2026

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anokfireball force-pushed the cross-hv-reqspec-early-commit branch from a9d7726 to 6eb48d6 Compare June 10, 2026 08:45

	'Instance must be running for cross-hypervisor resize. '
	reason='Instance must be running for cross-hypervisor resize. '

	class InvalidCrossHvResizePrecondition(NovaException):

	class InvalidCrossHvResizePrecondition(NovaException):

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anokfireball Jun 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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grandchild commented Jun 3, 2026

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grandchild commented Jun 1, 2026 •

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