Add VMware-to-KVM BFV-only resize by anokfireball · Pull Request #627 · sapcc/nova

anokfireball · 2026-06-12T08:36:44Z

Implements the VMware-to-KVM Cross-Hypervisor Instance Migration for boot-from-volume instances (only!) based on the ADR decision by adding (1) the conductor sanitization of image properties that would pin the instance to VMware HVs, (2) the required source-side VMware driver control flow, and (3) the confirm/revert control flow that commits/puts those properties back.

The cross-HV branches are guarded by _is_cross_hv_resize which currently still is a stub returning False. As a consequence, the overall feature is dormant: no flavor pair is allowlisted, no detection runs, no behavior changes. The feature activates once the detection layer allows a combo of source HV type and destination flavor (i.e. VMware to KVM).

The three commits map to the ADR's Resize Orchestration choice:

compute: RequestSpec sanitization for cross-HV resize. Sanitizes img_hv_type and the VMware bus/vif/scsi/video model fields from request_spec.image.properties before _schedule(), so the scheduler can pick a KVM host. Originals go into a new MigrationContext.old_image_properties field (versioned object v1.3) for revert. _move_claim carries the journal across the destination claim.
vmware: enable cross-HV BFV resize in VMware driver. Adds branches to migrate_disk_and_power_off, confirm_migration, and finish_revert_migration. Source-side power-off and volume/NIC detach use ReconfigVM only: no file deletion, no Cinder calls. The "shell" VM stays registered in vCenter under migration.uuid so confirm and revert can find it. Revert restores instanceUuid before re-attaching volumes, since the volume attach paths look up the VM by instance.uuid.
compute: revert path for cross-HV resize. Restores request_spec.image.properties and system_metadata['image_*'] from the MigrationContext journal during revert, before _update_volume_attachments and the driver call so the scheduler can pick a KVM host again.

Also as per ADR, there are no no Cinder retype during resize. The FCD driver keeps serving NFS connection_info to KVM connectors, and volumes stay typed vstorageobject. Customers run a standard os-retype when they are ready to change the volume type.

Sanitize VMware-specific image properties on the 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 the original values. The conductor saves this dict to MigrationContext.old_image_properties (via instance.save()) BEFORE the prep_resize cast, so the destination _move_claim can preserve it when rebuilding MigrationContext. The field mapping lives in CROSS_HV_SANITIZE_PROPS and is shared with the VMware driver system_metadata sanitizer so they agree on which properties to scrub. resource_tracker._move_claim() preserves any existing old_image_properties when it rebuilds MigrationContext on the destination, so the rollback dict survives the claim step. Change-Id: I56271a118ec3785eb5ba81a6f648e58d18169e73

Add cross-HV BFV branches to the three VMware driver resize methods: migrate_disk_and_power_off: - Detect cross-HV before _decode_host_addr (KVM dest uses plain IP) - Power off (tolerate already-off for Phase 2 idempotency) - Sanitize system_metadata image_* keys using shared CROSS_HV_SANITIZE_PROPS; save originals into MigrationContext.old_image_properties - Detach volumes and NICs via ReconfigVM (file is not deleted) - Swap instanceUuid to migration.uuid, rename shell - Return '[]' (libvirt finish_migration iterates this safely) - On retry, skip work if a shell already exists - On rollback after UUID swap, find the VM via migration.uuid confirm_migration: - Find shell by migration.uuid, destroy it - Tolerate missing shell (log and continue) - Clean all cross_hv_* markers from system_metadata finish_revert_migration: - Find shell by migration.uuid - Restore instanceUuid before volume re-attach (attach paths look up the VM by instance.uuid, so ordering matters) - Re-attach NICs and volumes, rename back - Power on Detection is a stub (returns False) until the detection/guardrails work lands separately. Change-Id: I3db51a7dc0cb1dfc1592959d9823250a93fd3358

Two restoration steps for cross-HV resize revert: 1. compute/api.py:revert_resize(): restore request_spec.image.properties from MigrationContext.old_image_properties and persist via reqspec.save(). Mirrors the existing reqspec.flavor revert. Only fires when old_image_properties is set (cross-HV resizes). 2. compute/manager.py:_finish_revert_resize(): restore system_metadata image_* keys from the MigrationContext dict BEFORE _update_volume_attachments and driver.finish_revert_migration, so the VMware driver sees the original values and the FCD driver returns VMware-protocol connection_info. cross_hv_* markers are cleaned AFTER the driver call returns. The VMware driver reads the marker to route to its cross-HV revert branch. Change-Id: Ib3689d4631c10b458802b450a3f40844766c90b9

BzzyBriel · 2026-06-16T15:56:17Z

        compute_utils.heal_reqspec_is_bfv(
            self.context, self.request_spec, self.instance)
+        self._old_image_properties = {}
+        src_hv = self._source_cn.hypervisor_type if self._source_cn else None


self._source_cn can not only be None in tests but also from this (obsolete) codepath

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 Co-authored-by: Jakob Karge <jakob.karge@sap.com> Co-authored-by: Fabian Koller <github@kthxbye.cyou>

anokfireball · 2026-06-17T07:54:53Z

            host_list=self.host_list)

+    def _prep_cross_hv_resize(self, src_hv: str, dest_hv: str):
+        if extra_specs_ops.match("VMware vCenter Server", src_hv) \


This is only whitelisting the combination for the conductor. We also need some check like this for the API layer... maybe compute_utils.is_supported_cross_hypervisor_resize or similar so the logic can be shared between the two locations similar to compute_utils.is_cross_hypervisor_resize.

Change-Id: Ia06d1e2f06226403b07f6e96806af056d49f610c

Change-Id: I4894fad4dcfab556818766d5a983bbe2645a9ea9

Change-Id: I74d1d48714e9fc441da97425ca45f82bbeb645bb

BzzyBriel · 2026-06-17T15:02:22Z

+                source_hv_type, dest_hv_type):
+            request_spec = objects.RequestSpec.get_by_instance_uuid(
+                context, instance.uuid)
+            compute_utils.raise_on_unsupported_cross_hypervisor_resize(


Again a test-breaking change. Some tests apparently expect this method to return before a request_spec is first requested from the database. We should fix those tests.

anokfireball changed the title ~~Cross hv vmware driver~~ Add VMware-to-KVM BFV resize Jun 12, 2026

anokfireball mentioned this pull request Jun 12, 2026

compute: RequestSpec sanitization for cross-HV resize #623

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anokfireball changed the title ~~Add VMware-to-KVM BFV resize~~ Add VMware-to-KVM BFV-only resize Jun 12, 2026

anokfireball added 3 commits June 16, 2026 11:11

anokfireball force-pushed the cross-hv-vmware-driver branch from 7de8abf to fa741a2 Compare June 16, 2026 09:11

BzzyBriel force-pushed the cross-hv-vmware-driver branch 3 times, most recently from bb2df8b to bd4f689 Compare June 16, 2026 15:51

BzzyBriel reviewed Jun 16, 2026

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BzzyBriel force-pushed the cross-hv-vmware-driver branch from bd4f689 to 074afbd Compare June 16, 2026 15:58

anokfireball commented Jun 17, 2026

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Comment thread nova/exception.py

anokfireball commented Jun 17, 2026

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Comment thread nova/conductor/manager.py Outdated

BzzyBriel added 3 commits June 17, 2026 13:57

remove redundant old_image_properties persist

298c90a

Change-Id: Ia06d1e2f06226403b07f6e96806af056d49f610c

handle InvalidCrossHvResizePrecondition in api

754840f

Change-Id: I4894fad4dcfab556818766d5a983bbe2645a9ea9

check cross-hv resize preconditions in API and conductor

8dc1531

Change-Id: I74d1d48714e9fc441da97425ca45f82bbeb645bb

BzzyBriel reviewed Jun 17, 2026

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Add VMware-to-KVM BFV-only resize#627

Add VMware-to-KVM BFV-only resize#627
anokfireball wants to merge 7 commits into
stable/2023.2-m3from
cross-hv-vmware-driver

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anokfireball commented Jun 12, 2026 •

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