Add a regression test for bug 1939545

Assert the behaviour of the libvirt driver during pre_live_migration
with instances that have block based volumes attached.

Bug #1939545 covering the case where the returned path from os-brick
isn't being saved into the connection_info of the associated bdm in
Nova.

The cinder fixture is extended as part of this change to offer
connection_info listing the iscsi volume type in order to correctly
assert the behaviour of the associated libvirt volume driver.

Conflicts: nova/tests/fixtures/cinder.py did not exist, applied
changes to CinderFixture class in nova/tests/fixtures.py. Also:
* Switched to using uuidsentinel instead of uuids, as the import is
  done as the former in stable/wallaby.
* Fixed the fakelibvirt import to match where it lives in
  stable/wallaby.
* Replace use of OSBrickFixture() that didn't exist in stable/wallaby
  with the fake_os_brick_connector from the libvirt unit tests.
* Fix fakelibvirt migrateToURI3 monkeypatch to use correct path for
  stable/wallaby.

Related-Bug: #1939545
Change-Id: I3f1073d70e4332737e33f3c9c00cf129d0ef76b4
(cherry picked from commit 268b716)

Author: lyarwood

nova/tests/fixtures.py

@@ -2435,6 +2435,26 @@ class CinderFixture(fixtures.Fixture):
     # as part of volume image metadata
     IMAGE_WITH_TRAITS_BACKED_VOL = '6194fc02-c60e-4a01-a8e5-600798208b5f'
 
+    # This represents a bootable volume backed by iSCSI storage.
+    ISCSI_BACKED_VOL = uuidsentinel.iscsi_backed_volume
+
+    # Dict of connection_info for the above volumes key'd by the volume id
+    # TODO(lyarwood): Make this unique and tracked per attachment somehow.
+    VOLUME_CONNECTION_INFO = {
+        uuidsentinel.iscsi_backed_volume: {
+            'driver_volume_type': 'iscsi',
+            'data': {
+                'target_lun': '1'
+            }
+        },
+        'fake': {
+            'driver_volume_type': 'fake',
+            'data': {
+                'foo': 'bar',
+            }
+        }
+    }
+
     def __init__(self, test, az='nova'):
         """Initialize this instance of the CinderFixture.
 
@@ -2593,7 +2613,14 @@ def fake_attachment_create(_self, context, volume_id, instance_uuid,
             attachment_id = uuidutils.generate_uuid()
             if self.attachment_error_id is not None:
                 attachment_id = self.attachment_error_id
-            attachment = {'id': attachment_id, 'connection_info': {'data': {}}}
+
+            attachment = {'id': attachment_id}
+
+            if connector:
+                connection_info = self.VOLUME_CONNECTION_INFO.get(
+                    volume_id, self.VOLUME_CONNECTION_INFO.get('fake'))
+                attachment['connection_info'] = copy.deepcopy(connection_info)
+
             self.volume_to_attachment[volume_id][attachment_id] = {
                 'id': attachment_id,
                 'instance_uuid': instance_uuid,
@@ -2631,13 +2658,9 @@ def fake_attachment_update(_self, context, attachment_id, connector,
             LOG.info('Updating volume attachment: %s', attachment_id)
             attachment_ref = {
                 'id': attachment_id,
-                'connection_info': {
-                    'driver_volume_type': 'fake',
-                    'data': {
-                        'foo': 'bar',
-                        'target_lun': '1'
-                    }
-                }
+                'connection_info': copy.deepcopy(
+                    self.VOLUME_CONNECTION_INFO.get(
+                        volume_id, self.VOLUME_CONNECTION_INFO.get('fake')))
             }
             if attachment_id == self.SWAP_ERR_ATTACH_ID:
                 # This intentionally triggers a TypeError for the
@@ -2646,13 +2669,15 @@ def fake_attachment_update(_self, context, attachment_id, connector,
             return attachment_ref
 
         def fake_attachment_get(_self, context, attachment_id):
-            # Ensure the attachment exists
-            _find_attachment(attachment_id)
-            attachment_ref = {'driver_volume_type': 'fake_type',
-                              'id': attachment_id,
-                              'connection_info': {'data':
-                                                  {'foo': 'bar',
-                                                   'target_lun': '1'}}}
+            # Ensure the attachment exists and grab the volume_id
+            volume_id, _, _ = _find_attachment(attachment_id)
+
+            attachment_ref = {
+                'id': attachment_id,
+                'connection_info': copy.deepcopy(
+                    self.VOLUME_CONNECTION_INFO.get(
+                        volume_id, self.VOLUME_CONNECTION_INFO.get('fake')))
+            }
             return attachment_ref
 
         def fake_get_all_volume_types(*args, **kwargs):

nova/tests/functional/regressions/test_bug_1939545.py

@@ -0,0 +1,111 @@
+# Copyright 2021, Red Hat, Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import fixtures
+import mock
+
+from oslo_serialization import jsonutils
+
+from nova import context
+from nova import objects
+from nova.tests.functional import integrated_helpers
+from nova.tests.functional.libvirt import base
+from nova.tests.unit.virt.libvirt import fake_os_brick_connector
+from nova.tests.unit.virt.libvirt import fakelibvirt
+
+
+class TestLiveMigrateUpdateDevicePath(
+    base.ServersTestBase,
+    integrated_helpers.InstanceHelperMixin
+):
+    """Regression test for bug 1939545
+
+    Assert the behaviour of the libvirt driver during pre_live_migration with
+    instances that have block based volumes attached.
+
+    Bug #1939545 covering the case where the returned path from os-brick
+    isn't being saved into the connection_info of the associated bdm in Nova.
+    """
+
+    api_major_version = 'v2.1'
+    microversion = 'latest'
+    ADMIN_API = True
+
+    def setUp(self):
+        super().setUp()
+
+        self.useFixture(fixtures.MonkeyPatch(
+            'nova.virt.libvirt.driver.connector',
+            fake_os_brick_connector))
+
+        # TODO(lyarwood): Move into base.ServersTestBase to allow live
+        # migrations to pass without changes by the test classes.
+        self.useFixture(fixtures.MonkeyPatch(
+            'nova.tests.unit.virt.libvirt.fakelibvirt.Domain.migrateToURI3',
+            self._migrate_stub))
+
+        self.start_compute(
+            hostname='src',
+            host_info=fakelibvirt.HostInfo(
+                cpu_nodes=1, cpu_sockets=1, cpu_cores=4, cpu_threads=1))
+        self.start_compute(
+            hostname='dest',
+            host_info=fakelibvirt.HostInfo(
+                cpu_nodes=1, cpu_sockets=1, cpu_cores=4, cpu_threads=1))
+
+    def _migrate_stub(self, domain, destination, params, flags):
+        dest = self.computes['dest']
+        dest.driver._host.get_connection().createXML(
+            params['destination_xml'],
+            'fake-createXML-doesnt-care-about-flags')
+        source = self.computes['src']
+        conn = source.driver._host.get_connection()
+        dom = conn.lookupByUUIDString(self.server['id'])
+        dom.complete_job()
+
+    # TODO(lyarwood): Move this into the os-brick fixture and repeat for all
+    # provided connectors at runtime.
+    @mock.patch(
+        'os_brick.initiator.connectors.iscsi.ISCSIConnector.connect_volume')
+    @mock.patch(
+        'os_brick.initiator.connectors.iscsi.ISCSIConnector.disconnect_volume')
+    def test_live_migrate_update_device_path(
+        self, mock_disconnect_volume, mock_connect_volume
+    ):
+        self.server = self._create_server(host='src', networks='none')
+        volume_id = self.cinder.ISCSI_BACKED_VOL
+
+        # TODO(lyarwood): As above, move this into the os-brick fixture.
+        mock_connect_volume.return_value = {'path': '/dev/sda'}
+
+        self.api.post_server_volume(
+            self.server['id'], {'volumeAttachment': {'volumeId': volume_id}})
+
+        # Get the volume bdm and assert that the connection_info is set with
+        # device_path from the volume driver.
+        ctxt = context.get_admin_context()
+        bdm = objects.BlockDeviceMapping.get_by_volume_and_instance(
+            ctxt, volume_id, self.server['id'])
+        connection_info = jsonutils.loads(bdm.connection_info)
+        self.assertIn('device_path', connection_info.get('data'))
+
+        # Live migrate the instance to another host
+        self._live_migrate(self.server)
+
+        # FIXME(lyarwood): This is bug #1939545, again get the volume bdm and
+        # assert that the saved connection_info doesn't contain device_path.
+        bdm = objects.BlockDeviceMapping.get_by_volume_and_instance(
+            ctxt, volume_id, self.server['id'])
+        connection_info = jsonutils.loads(bdm.connection_info)
+        self.assertNotIn('device_path', connection_info.get('data'))