Added support for live migration on non-shared storage

Watcher applier should be able to live migrate instances on any storage
type. To do this watcher will catch error 400 returned from nova if we
try to live migrate instance which is not on shared storage and live
migrate instance using block_migrate.

Added unit tests, changed action in watcher applier.

Closes-bug: #1549307

Change-Id: I97e583c9b4a0bb9daa1d39e6d652d6474a5aaeb1

watcher/applier/actions/migration.py

@@ -21,7 +21,7 @@ from oslo_log import log
 import six
 import voluptuous
 
-from watcher._i18n import _
+from watcher._i18n import _, _LC
 from watcher.applier.actions import base
 from watcher.common import exception
 from watcher.common import nova_helper
@@ -76,6 +76,31 @@ class Migrate(base.BaseAction):
     def src_hypervisor(self):
         return self.input_parameters.get(self.SRC_HYPERVISOR)
 
+    def _live_migrate_instance(self, nova, destination):
+        result = None
+        try:
+            result = nova.live_migrate_instance(instance_id=self.instance_uuid,
+                                                dest_hostname=destination)
+        except nova_helper.nvexceptions.ClientException as e:
+            if e.code == 400:
+                LOG.debug("Live migration of instance %s failed. "
+                          "Trying to live migrate using block migration."
+                          % self.instance_uuid)
+                result = nova.live_migrate_instance(
+                    instance_id=self.instance_uuid,
+                    dest_hostname=destination,
+                    block_migration=True)
+            else:
+                LOG.debug("Nova client exception occured while live migrating "
+                          "instance %s.Exception: %s" %
+                          (self.instance_uuid, e))
+        except Exception:
+            LOG.critical(_LC("Unexpected error occured. Migration failed for"
+                             "instance %s. Leaving instance on previous "
+                             "host."), self.instance_uuid)
+
+        return result
+
     def migrate(self, destination):
         nova = nova_helper.NovaHelper(osc=self.osc)
         LOG.debug("Migrate instance %s to %s", self.instance_uuid,
@@ -83,8 +108,7 @@ class Migrate(base.BaseAction):
         instance = nova.find_instance(self.instance_uuid)
         if instance:
             if self.migration_type == 'live':
-                return nova.live_migrate_instance(
-                    instance_id=self.instance_uuid, dest_hostname=destination)
+                return self._live_migrate_instance(nova, destination)
             else:
                 raise exception.Invalid(
                     message=(_('Migration of type %(migration_type)s is not '

watcher/tests/applier/actions/test_migration.py

@@ -157,7 +157,10 @@ class TestMigration(base.TestCase):
     def test_execute_live_migration(self):
         self.m_helper.find_instance.return_value = self.INSTANCE_UUID
 
-        self.action.execute()
+        try:
+            self.action.execute()
+        except Exception as exc:
+            self.fail(exc)
 
         self.m_helper.live_migrate_instance.assert_called_once_with(
             instance_id=self.INSTANCE_UUID,
@@ -173,3 +176,31 @@ class TestMigration(base.TestCase):
             instance_id=self.INSTANCE_UUID,
             dest_hostname="hypervisor1-hostname"
         )
+
+    def test_live_migrate_non_shared_storage_instance(self):
+        self.m_helper.find_instance.return_value = self.INSTANCE_UUID
+
+        self.m_helper.live_migrate_instance.side_effect = [
+            nova_helper.nvexceptions.ClientException(400, "BadRequest"), True]
+
+        try:
+            self.action.execute()
+        except Exception as exc:
+            self.fail(exc)
+
+        self.m_helper.live_migrate_instance.assert_has_calls([
+            mock.call(instance_id=self.INSTANCE_UUID,
+                      dest_hostname="hypervisor2-hostname"),
+            mock.call(instance_id=self.INSTANCE_UUID,
+                      dest_hostname="hypervisor2-hostname",
+                      block_migration=True)
+            ])
+
+        expected = [mock.call.first(instance_id=self.INSTANCE_UUID,
+                                    dest_hostname="hypervisor2-hostname"),
+                    mock.call.second(instance_id=self.INSTANCE_UUID,
+                                     dest_hostname="hypervisor2-hostname",
+                                     block_migration=True)
+                    ]
+        self.m_helper.live_migrate_instance.mock_calls == expected
+        self.assertEqual(2, self.m_helper.live_migrate_instance.call_count)