nova/releasenotes/notes/bug-1853009-99414e14d1491b5f.yaml
Mark Goddard a8492e8878 Prevent deletion of a compute node belonging to another host
There is a race condition in nova-compute with the ironic virt driver as
nodes get rebalanced. It can lead to compute nodes being removed in the
DB and not repopulated. Ultimately this prevents these nodes from being
scheduled to.

The main race condition involved is in update_available_resources in
the compute manager. When the list of compute nodes is queried, there is
a compute node belonging to the host that it does not expect to be
managing, i.e. it is an orphan. Between that time and deleting the
orphan, the real owner of the compute node takes ownership of it ( in
the resource tracker). However, the node is still deleted as the first
host is unaware of the ownership change.

This change prevents this from occurring by filtering on the host when
deleting a compute node. If another compute host has taken ownership of
a node, it will have updated the host field and this will prevent
deletion from occurring. The first host sees this has happened via the
ComputeHostNotFound exception, and avoids deleting its resource
provider.

Co-Authored-By: melanie witt <melwittt@gmail.com>

Closes-Bug: #1853009
Related-Bug: #1841481

Change-Id: I260c1fded79a85d4899e94df4d9036a1ee437f02
2021-08-20 14:57:45 +01:00

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---
fixes:
- |
Fixes an issue with multiple ``nova-compute`` services used with Ironic,
where a rebalance operation could result in a compute node being deleted
from the database and not recreated. See `bug 1853009
<https://bugs.launchpad.net/nova/+bug/1853009>`__ for details.