Raise NoValidHost if no allocation candidates

Placement took over the role of the CoreFilter, RamFilter and DiskFilter
from the FilterScheduler. Therefore if placement returns no allocation
candidates for a request then scheduling should be stopped as this means
there is not enough VCPU, MEMORY_MB, or DISK_GB available in any compute
node for the request.

Change-Id: If20a20e5cce7ab490998643e32556a1016646b07
Closes-Bug: #1708637

nova/scheduler/manager.py

@@ -134,13 +134,7 @@ class SchedulerManager(manager.Manager):
                           "API. This may be a temporary occurrence as compute "
                           "nodes start up and begin reporting inventory to "
                           "the Placement service.")
-                # TODO(jaypipes): Setting provider_summaries to None triggers
+                raise exception.NoValidHost(reason="")
-                # the scheduler to load all compute nodes to do scheduling "the
-                # old way".  Really, we should raise NoValidHosts here, but all
-                # functional tests will fall over if we do that without
-                # changing the PlacementFixture to load compute node inventory
-                # into the placement database before starting functional tests.
-                provider_summaries = None
             else:
                 # Build a dict of lists of allocation requests, keyed by
                 # provider UUID, so that when we attempt to claim resources for

nova/tests/functional/test_servers.py

@@ -1612,22 +1612,13 @@ class ServerMovingTests(test.TestCase, integrated_helpers.InstanceHelperMixin):
             }
         }
 
-        # NOTE(gibi): This is bug 1708637. Placement returns no allocation
+        resp = self.api.post_server_action(
-        # candidate and the scheduler falls back to the legacy filtering. As
+            server['id'], resize_req, check_response_status=[400])
-        # CoreFilter is not enabled the filtering result in hosts selected
+        self.assertEqual(
-        # without enough VCPU resource
+            resp['badRequest']['message'],
-        self.api.post_server_action(server['id'], resize_req)
+            "No valid host was found. No valid host found for resize")
-        server = self._wait_for_state_change(self.api, server, 'VERIFY_RESIZE')
+        server = self.admin_api.get_server(server['id'])
-        self.assertEqual(dest_hostname, server['OS-EXT-SRV-ATTR:host'])
+        self.assertEqual(source_hostname, server['OS-EXT-SRV-ATTR:host'])
-
-        # Note(gibi): After bug 1708637 is fixed the following is expected
-        # resp = self.api.post_server_action(
-        #     server['id'], resize_req, check_response_status=[400])
-        # self.assertEqual(
-        #     resp['badRequest']['message'],
-        #     "No valid host was found. No valid host found for resize")
-        # server = self.admin_api.get_server(server['id'])
-        # self.assertEqual(source_hostname, server['OS-EXT-SRV-ATTR:host'])
 
         # only the source host shall have usages after the failed resize
         source_usages = self._get_provider_usages(source_rp_uuid)

nova/tests/unit/scheduler/test_scheduler.py

@@ -18,6 +18,7 @@ Tests For Scheduler
 """
 
 import mock
+import oslo_messaging as messaging
 
 import nova.conf
 from nova import context
@@ -127,67 +128,45 @@ class SchedulerManagerTestCase(test.NoDBTestCase):
     @mock.patch('nova.scheduler.utils.resources_from_request_spec')
     @mock.patch('nova.scheduler.client.report.SchedulerReportClient.'
                 'get_allocation_candidates')
-    def test_select_destination_old_placement(self, mock_get_ac, mock_rfrs):
+    def _test_select_destination(self, get_allocation_candidates_response,
-        """Tests that we will pass None for the provider_summaries parameter to
+                                 mock_get_ac, mock_rfrs):
-        the scheduler driver select_destinations() method when the scheduler
-        report client's get_allocation_candidates() returns None, None as it
-        would if placement service hasn't been upgraded before scheduler.
-        """
         fake_spec = objects.RequestSpec()
         fake_spec.instance_uuid = uuids.instance
-        place_res = (None, None)
+        place_res = get_allocation_candidates_response
         mock_get_ac.return_value = place_res
         with mock.patch.object(self.manager.driver, 'select_destinations'
                 ) as select_destinations:
-            self.manager.select_destinations(None, spec_obj=fake_spec,
+            self.assertRaises(messaging.rpc.dispatcher.ExpectedException,
+                    self.manager.select_destinations, None, spec_obj=fake_spec,
                     instance_uuids=[fake_spec.instance_uuid])
-            select_destinations.assert_called_once_with(None, fake_spec,
+            select_destinations.assert_not_called()
-                    [fake_spec.instance_uuid], None, None)
             mock_get_ac.assert_called_once_with(mock_rfrs.return_value)
 
-    @mock.patch('nova.scheduler.utils.resources_from_request_spec')
+    def test_select_destination_old_placement(self):
-    @mock.patch('nova.scheduler.client.report.SchedulerReportClient.'
+        """Tests that we will raise NoValidhost when the scheduler
-                'get_allocation_candidates', return_value=None)
+        report client's get_allocation_candidates() returns None, None as it
-    def test_select_destination_placement_connect_fails(
+        would if placement service hasn't been upgraded before scheduler.
-            self, mock_get_ac, mock_rfrs):
+        """
-        """Tests that we will pass None for the provider_summaries parameter to
+        place_res = (None, None)
-        the scheduler driver select_destinations() method when the scheduler
+        self._test_select_destination(place_res)
+
+    def test_select_destination_placement_connect_fails(self):
+        """Tests that we will raise NoValidHost when the scheduler
         report client's get_allocation_candidates() returns None, which it
         would if the connection to Placement failed and the safe_connect
         decorator returns None.
         """
-        fake_spec = objects.RequestSpec()
+        place_res = None
-        fake_spec.instance_uuid = uuids.instance
+        self._test_select_destination(place_res)
-        with mock.patch.object(self.manager.driver,
-                               'select_destinations') as select_destinations:
-            self.manager.select_destinations(
-                self.context, spec_obj=fake_spec,
-                instance_uuids=[fake_spec.instance_uuid])
-            select_destinations.assert_called_once_with(
-                self.context, fake_spec, [fake_spec.instance_uuid], None, None)
-            mock_get_ac.assert_called_once_with(mock_rfrs.return_value)
 
-    @mock.patch('nova.scheduler.utils.resources_from_request_spec')
+    def test_select_destination_no_candidates(self):
-    @mock.patch('nova.scheduler.client.report.SchedulerReportClient.'
+        """Tests that we will raise NoValidHost when the scheduler
-                'get_allocation_candidates')
-    def test_select_destination_no_candidates(self, mock_get_ac, mock_rfrs):
-        """Tests that we will pass None for the provider_summaries parameter to
-        the scheduler driver select_destinations() method when the scheduler
         report client's get_allocation_candidates() returns [], {} which it
         would if placement service hasn't yet had compute nodes populate
         inventory.
         """
-        fake_spec = objects.RequestSpec()
-        fake_spec.instance_uuid = uuids.instance
         place_res = ([], {})
-        mock_get_ac.return_value = place_res
+        self._test_select_destination(place_res)
-        with mock.patch.object(self.manager.driver, 'select_destinations'
-                ) as select_destinations:
-            self.manager.select_destinations(None, spec_obj=fake_spec,
-                    instance_uuids=[fake_spec.instance_uuid])
-            select_destinations.assert_called_once_with(None, fake_spec,
-                    [fake_spec.instance_uuid], None, None)
-            mock_get_ac.assert_called_once_with(mock_rfrs.return_value)
 
     @mock.patch('nova.scheduler.utils.resources_from_request_spec')
     @mock.patch('nova.scheduler.client.report.SchedulerReportClient.'