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Restore soft-deleted compute node with same uuid

There is a unique index on the compute_nodes.uuid column which
means we can't have more than one compute_nodes record in the
same DB with the same UUID even if one is soft deleted because
the deleted column is not part of that unique index constraint.

This is a problem with ironic nodes where the node is 1:1 with
the compute node record, and when a node is undergoing maintenance
the driver doesn't return it from get_available_nodes() so the
ComputeManager.update_available_resource periodic task (soft)
deletes the compute node record, but when the node is no longer
under maintenance in ironic and the driver reports it, the
ResourceTracker._init_compute_node code will fail to create the
ComputeNode record again because of the duplicate uuid.

This change handles the DBDuplicateEntry error in compute_node_create
by finding the soft-deleted compute node with the same uuid and
simply updating it to no longer be (soft) deleted.

Closes-Bug: #1839560

Change-Id: Iafba419fe86446ffe636721f523fb619f8f787b3
Matt Riedemann 1 year ago
3 changed files with 74 additions and 24 deletions
  1. +45
  2. +17
  3. +12

+ 45
- 1
nova/db/sqlalchemy/ View File

@@ -30,6 +30,7 @@ from oslo_db.sqlalchemy import enginefacade
from oslo_db.sqlalchemy import update_match
from oslo_db.sqlalchemy import utils as sqlalchemyutils
from oslo_log import log as logging
from oslo_utils import excutils
from oslo_utils import importutils
from oslo_utils import timeutils
from oslo_utils import uuidutils
@@ -696,11 +697,54 @@ def compute_node_create(context, values):

compute_node_ref = models.ComputeNode()
except db_exc.DBDuplicateEntry:
with excutils.save_and_reraise_exception(logger=LOG) as err_ctx:
# Check to see if we have a (soft) deleted ComputeNode with the
# same UUID and if so just update it and mark as no longer (soft)
# deleted. See bug 1839560 for details.
if 'uuid' in values:
# Get a fresh context for a new DB session and allow it to
# get a deleted record.
ctxt = nova.context.get_admin_context(read_deleted='yes')
compute_node_ref = _compute_node_get_and_update_deleted(
ctxt, values)
# If we didn't get anything back we failed to find the node
# by uuid and update it so re-raise the DBDuplicateEntry.
if compute_node_ref:
err_ctx.reraise = False

return compute_node_ref

def _compute_node_get_and_update_deleted(context, values):
"""Find a ComputeNode by uuid, update and un-delete it.

This is a special case from the ``compute_node_create`` method which
needs to be separate to get a new Session.

This method will update the ComputeNode, if found, to have deleted=0 and
deleted_at=None values.

:param context: request auth context which should be able to read deleted
:param values: values used to update the ComputeNode record - must include
:return: updated ComputeNode sqlalchemy model object if successfully found
and updated, None otherwise
cn = model_query(
context, models.ComputeNode).filter_by(uuid=values['uuid']).first()
if cn:
# Update with the provided values but un-soft-delete.
update_values = copy.deepcopy(values)
update_values['deleted'] = 0
update_values['deleted_at'] = None
return compute_node_update(context,, update_values)

@oslo_db_api.wrap_db_retry(max_retries=5, retry_on_deadlock=True)
def compute_node_update(context, compute_id, values):

+ 17
- 23
nova/tests/functional/regressions/ View File

@@ -14,7 +14,6 @@ from oslo_log import log as logging

from nova import context
from nova.db import api as db_api
from nova import exception
from nova import objects
from nova import test
from nova.tests import fixtures as nova_fixtures
@@ -93,30 +92,25 @@ class PeriodicNodeRecreateTestCase(test.TestCase,
# Now stub the driver again to report node2 as being back and run
# the periodic task.
compute.manager.driver._set_nodes(['node1', 'node2'])'Running update_available_resource which should bring back '
# FIXME(mriedem): This is bug 1839560 where the ResourceTracker fails
# to create a ComputeNode for node2 because of conflicting UUIDs.
# The DBDuplicateEntry error should have been handled and resulted in
# updating the (soft) deleted record to no longer be deleted.
log = self.stdlog.logger.output
self.assertIn('Error updating resources for node node2', log)
self.assertIn('DBDuplicateEntry', log)
# Should still only have one reported hypervisor (node1).
self.assertNotIn('DBDuplicateEntry', log)
# Should have two reported hypervisors again.
hypervisors = self.api.api_get('/os-hypervisors').body['hypervisors']
self.assertEqual(1, len(hypervisors), hypervisors)
# Test the workaround for bug 1839560 by archiving the deleted node2
# compute_nodes table record which will allow the periodic to create a
# new entry for node2. We can remove this when the bug is fixed.
self.assertEqual(2, len(hypervisors), hypervisors)
# Now that the node2 record was un-soft-deleted, archiving should not
# remove any compute_nodes.'Archiving the database.')
archived = db_api.archive_deleted_rows(1000)[0]
self.assertIn('compute_nodes', archived)
self.assertEqual(1, archived['compute_nodes'])
with utils.temporary_mutation(ctxt, read_deleted='yes'):
ctxt, 'node1', 'node2')
# Now run the periodic again and we should have a new ComputeNode for
# node2.'Running update_available_resource which should create a new '
'ComputeNode record for node2.')
hypervisors = self.api.api_get('/os-hypervisors').body['hypervisors']
self.assertEqual(2, len(hypervisors), hypervisors)
self.assertNotIn('compute_nodes', archived)
cn2 = objects.ComputeNode.get_by_host_and_nodename(
ctxt, 'node1', 'node2')
# The node2 id and uuid should not have changed in the DB.
self.assertEqual(cn.uuid, cn2.uuid)

+ 12
- 0
nova/tests/unit/db/ View File

@@ -7215,6 +7215,18 @@ class ComputeNodeTestCase(test.TestCase, ModelsObjectComparatorMixin):
new_stats = jsonutils.loads(self.item['stats'])
self.assertEqual(self.stats, new_stats)

def test_compute_node_create_duplicate_host_hypervisor_hostname(self):
"""Tests to make sure that DBDuplicateEntry is raised when trying to
create a duplicate ComputeNode with the same host and
hypervisor_hostname values but different uuid values. This makes
sure that when _compute_node_get_and_update_deleted returns None
the DBDuplicateEntry is re-raised.
other_node = dict(self.compute_node_dict)
other_node['uuid'] = uuidutils.generate_uuid()
db.compute_node_create, self.ctxt, other_node)

def test_compute_node_get_all(self):
nodes = db.compute_node_get_all(self.ctxt)
self.assertEqual(1, len(nodes))