func: Add live migration rollback volume attachment tests

This test asserts that the original source host volume attachments
remain intact after a failure and rollback during the main live
migration flow on the virt driver.

Change-Id: If1a45886adfc6448a626a54449ff66f400879b83
(cherry picked from commit e6c2a863286bae6a8a8caff0d6a54c001e0a2ffb)

1 files changed, 93 insertions, 0 deletions

diff --git a/nova/tests/functional/compute/test_live_migration.py b/nova/tests/functional/compute/test_live_migration.py
index 083dadf774..160a898bda 100644
--- a/nova/tests/functional/compute/test_live_migration.py
+++ b/nova/tests/functional/compute/test_live_migration.py
@@ -12,9 +12,11 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import mock
 from oslo_utils.fixture import uuidsentinel as uuids
 
 from nova import exception
+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
@@ -91,3 +93,94 @@ class LiveMigrationCinderFailure(integrated_helpers._IntegratedTestBase):
                                          'status': 'ACTIVE'})
         self.assertEqual(2, stub_attachment_delete.call_count)
         self.assertEqual(1, stub_attachment_delete.raise_count)
+
+
+class TestVolAttachmentsDuringLiveMigration(
+    integrated_helpers._IntegratedTestBase
+):
+    """Assert the lifecycle of volume attachments during LM rollbacks
+    """
+
+    # Default self.api to the self.admin_api as live migration is admin only
+    ADMIN_API = True
+    microversion = 'latest'
+
+    def setUp(self):
+        super().setUp()
+        self.cinder = self.useFixture(nova_fixtures.CinderFixture(self))
+
+    def _setup_compute_service(self):
+        self._start_compute('src')
+        self._start_compute('dest')
+
+    @mock.patch('nova.virt.fake.FakeDriver.live_migration')
+    def test_vol_attachments_during_driver_live_mig_failure(self, mock_lm):
+        """Assert volume attachments during live migration rollback
+
+        * Mock live_migration to always rollback and raise a failure within the
+          fake 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
+          live_migration method
+        * Assert that the instance is still on the source host
+        * Assert that the original source host volume attachment remains
+        """
+        # Mock out driver.live_migration so that we always rollback
+        def _fake_live_migration_with_rollback(
+                context, instance, dest, post_method, recover_method,
+                block_migration=False, migrate_data=None):
+            # Just call the recover_method to simulate a rollback
+            recover_method(context, instance, dest, migrate_data)
+            # raise test.TestingException here to imitate a virt driver
+            raise test.TestingException()
+        mock_lm.side_effect = _fake_live_migration_with_rollback
+
+        volume_id = nova_fixtures.CinderFixture.IMAGE_BACKED_VOL
+        server = self._build_server(
+            name='test_bfv_live_migration_failure', image_uuid='',
+            networks='none'
+        )
+        server['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(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 live_migration raising TestingException
+        self.api.post_server_action(
+            server['id'],
+            {'os-migrateLive': {'host': None, 'block_migration': 'auto'}})
+        self._wait_for_migration_status(server, ['error'])
+
+        # Assert that we called the fake live_migration method
+        mock_lm.assert_called_once()
+
+        # Assert that the instance is listed as ERROR on the source
+        self._wait_for_state_change(server, 'ERROR')
+        server = self.api.get_server(server['id'])
+        self.assertEqual(src_host, server['OS-EXT-SRV-ATTR:host'])
+
+        # Assert that the src attachment is still present
+        attachments = self.cinder.volume_to_attachment.get(volume_id)
+        self.assertIn(src_attachment_id, attachments.keys())
+        self.assertEqual(1, len(attachments))