Add regression tests for bug #1889108

NOTE(lyarwood): nova.virt.fake.set_nodes() is required on stable/queens
to avoid duplicate hostnames.

Related-Bug: #1889108
Change-Id: Ib9dbc792dc918e7ea45915e2c1dbd96be82ef562
(cherry picked from commit 4c970f499c)
(cherry picked from commit 6db72002a6)
(cherry picked from commit 6a9bb79fc0)
(cherry picked from commit 06d9d0d705)
(cherry picked from commit 7b2662c85c)

nova/tests/functional/regressions/test_bug_1889108.py

@@ -0,0 +1,122 @@
+# 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 mock
+
+from nova import test
+
+from nova.tests import fixtures as nova_fixtures
+from nova.tests.functional import integrated_helpers
+from nova.tests.unit import fake_notifier
+from nova.virt import fake
+
+
+class TestVolAttachmentsDuringPreLiveMigration(
+    integrated_helpers._IntegratedTestBase,
+    integrated_helpers.InstanceHelperMixin
+):
+    """Regression test for bug 1889108.
+
+    This regression test asserts that the original source volume attachments
+    are incorrectly removed during the rollback from pre_live_migration
+    failures on the destination.
+    """
+    api_major_version = 'v2.1'
+    microversion = 'latest'
+    ADMIN_API = True
+    USE_NEUTRON = True
+
+    def setUp(self):
+        super(TestVolAttachmentsDuringPreLiveMigration, self).setUp()
+        self.cinder = self.useFixture(
+            nova_fixtures.CinderFixtureNewAttachFlow(self))
+        fake_notifier.stub_notifier(self)
+        self.addCleanup(fake_notifier.reset)
+
+    def _setup_compute_service(self):
+        # Start a second compte node (the first one was started for us by
+        # _IntegratedTestBase. set_nodes() is needed to avoid duplicate
+        # nodenames. See comments in test_bug_1702454.py.
+        fake.set_nodes(['src'])
+        self.addCleanup(fake.restore_nodes)
+        self.start_service('compute', host='src')
+        fake.set_nodes(['dest'])
+        self.addCleanup(fake.restore_nodes)
+        self.start_service('compute', host='dest')
+
+    @mock.patch('nova.virt.fake.FakeDriver.pre_live_migration',
+                side_effect=test.TestingException)
+    def test_vol_attachments_during_driver_pre_live_mig_failure(
+            self, mock_plm):
+        """Assert that the src attachment is incorrectly removed
+
+        * Mock pre_live_migration to always fail within the virt driver
+        * Launch a boot from volume instance
+        * Assert that the volume is attached correctly to the instance.
+        * Live migrate the instance to another host invoking the mocked
+          pre_live_migration
+        * Assert that the instance is still on the source host
+        * Assert that both the original source host volume attachment and
+          new destination volume attachment have been removed
+        """
+        volume_id = nova_fixtures.CinderFixture.IMAGE_BACKED_VOL
+        server = {
+            'name': 'test_bfv_pre_live_migration_failure',
+            'flavorRef': 1,
+            'imageRef': '',
+            'networks': 'none',
+            'block_device_mapping_v2': [{
+                'source_type': 'volume',
+                'destination_type': 'volume',
+                'boot_index': 0,
+                'uuid': volume_id}],
+        }
+        server = self.api.post_server({'server': server})
+        self._wait_for_state_change(self.api, server, 'ACTIVE')
+
+        # Fetch the source host for use later
+        server = self.api.get_server(server['id'])
+        src_host = server['OS-EXT-SRV-ATTR:host']
+
+        # Assert that the volume is connected to the instance
+        self.assertIn(
+            volume_id, self.cinder.volume_ids_for_instance(server['id']))
+
+        # Assert that we have an active attachment in the fixture
+        attachments = self.cinder.volume_to_attachment.get(volume_id)
+        self.assertEqual(1, len(attachments))
+
+        # Fetch the attachment_id for use later once we have migrated
+        src_attachment_id = list(attachments.keys())[0]
+
+        # Migrate the instance and wait until the migration errors out thanks
+        # to our mocked version of pre_live_migration raising
+        # test.TestingException
+        self.api.post_server_action(
+            server['id'],
+            {'os-migrateLive': {'host': None, 'block_migration': 'auto'}})
+        self._wait_for_state_change(self.api, server, 'ACTIVE')
+        self._wait_for_migration_status(server, ['error'])
+
+        # Assert that we called the fake pre_live_migration method
+        mock_plm.assert_called_once()
+
+        # Assert that the instance is listed on the source
+        server = self.api.get_server(server['id'])
+        self.assertEqual(src_host, server['OS-EXT-SRV-ATTR:host'])
+
+        # FIXME(lyarwood): Assert that both the src and dest attachments have
+        # been removed. Only the dest attachment should be removed during the
+        # rollback of a pre_live_migration failure.
+        attachments = self.cinder.volume_to_attachment.get(volume_id)
+        self.assertNotIn(src_attachment_id, attachments.keys())
+        self.assertEqual(0, len(attachments))