ironic: stop lying to the RT when ironic is down

Returning an empty list of nodes can cause all sorts of crazy behavior,
so we instead bubble up a VirtDriverNotReady exception, which the compute
manager will ignore.

Change-Id: Ib0ec1012b74e9a9e74c8879f3feed5f9332b711f
Related-Bug: #1744139
Closes-Bug: #1750450

nova/compute/manager.py

@@ -7317,7 +7317,12 @@ class ComputeManager(manager.Manager):
         compute_nodes_in_db = self._get_compute_nodes_in_db(context,
                                                             use_slave=True,
                                                             startup=startup)
-        nodenames = set(self.driver.get_available_nodes())
+        try:
+            nodenames = set(self.driver.get_available_nodes())
+        except exception.VirtDriverNotReady:
+            LOG.warning("Virt driver is not ready.")
+            return
+
         for nodename in nodenames:
             self.update_available_resource_for_node(context, nodename)
 

nova/exception.py

@@ -2299,3 +2299,7 @@ class CannotMigrateWithTargetHost(NovaException):
 
 class CannotMigrateToSameHost(NovaException):
     msg_fmt = _("Cannot migrate to the host where the server exists.")
+
+
+class VirtDriverNotReady(NovaException):
+    msg_fmt = _("Virt driver is not ready.")

nova/tests/unit/compute/test_compute_mgr.py

@@ -250,6 +250,26 @@ class ComputeManagerUnitTestCase(test.NoDBTestCase):
             else:
                 self.assertFalse(db_node.destroy.called)
 
+    @mock.patch('nova.scheduler.client.report.SchedulerReportClient.'
+                'delete_resource_provider')
+    @mock.patch.object(manager.ComputeManager,
+                       'update_available_resource_for_node')
+    @mock.patch.object(fake_driver.FakeDriver, 'get_available_nodes')
+    @mock.patch.object(manager.ComputeManager, '_get_compute_nodes_in_db')
+    def test_update_available_resource_not_ready(self, get_db_nodes,
+                                                 get_avail_nodes,
+                                                 update_mock,
+                                                 del_rp_mock):
+        db_nodes = [self._make_compute_node('node1', 1)]
+        get_db_nodes.return_value = db_nodes
+        get_avail_nodes.side_effect = exception.VirtDriverNotReady
+
+        self.compute.update_available_resource(self.context)
+
+        # these shouldn't get processed on VirtDriverNotReady
+        update_mock.assert_not_called()
+        del_rp_mock.assert_not_called()
+
     @mock.patch('nova.context.get_admin_context')
     def test_pre_start_hook(self, get_admin_context):
         """Very simple test just to make sure update_available_resource is

nova/tests/unit/virt/ironic/test_driver.py

@@ -534,10 +534,10 @@ class IronicDriverTestCase(test.NoDBTestCase):
     @mock.patch.object(objects.Instance, 'get_by_uuid')
     def test_list_instances_fail(self, mock_inst_by_uuid, mock_call):
         mock_call.side_effect = exception.NovaException
-        response = self.driver.list_instances()
+        self.assertRaises(exception.VirtDriverNotReady,
+                          self.driver.list_instances)
         mock_call.assert_called_with("node.list", associated=True, limit=0)
         self.assertFalse(mock_inst_by_uuid.called)
-        self.assertThat(response, matchers.HasLength(0))
 
     @mock.patch.object(cw.IronicClientWrapper, 'call')
     def test_list_instance_uuids(self, mock_call):
@@ -2311,9 +2311,9 @@ class IronicDriverTestCase(test.NoDBTestCase):
         result = self.driver._get_node_list()
         mock_error.assert_not_called()
         self.assertEqual(["node1", "node2"], result)
-        result = self.driver._get_node_list()
+        self.assertRaises(exception.VirtDriverNotReady,
+                          self.driver._get_node_list)
         mock_error.assert_called_once()
-        self.assertEqual([], result)
 
 
 class IronicDriverSyncTestCase(IronicDriverTestCase):

nova/virt/ironic/driver.py

@@ -576,6 +576,7 @@ class IronicDriver(virt_driver.ComputeDriver):
         If unable to connect ironic server, an empty list is returned.
 
         :returns: a list of raw node from ironic
+        :raises: VirtDriverNotReady
 
         """
         node_list = []
@@ -584,15 +585,18 @@ class IronicDriver(virt_driver.ComputeDriver):
         except exception.NovaException as e:
             LOG.error("Failed to get the list of nodes from the Ironic "
                       "inventory. Error: %s", e)
+            raise exception.VirtDriverNotReady()
         except Exception as e:
             LOG.error("An unknown error has occurred when trying to get the "
                       "list of nodes from the Ironic inventory. Error: %s", e)
+            raise exception.VirtDriverNotReady()
         return node_list
 
     def list_instances(self):
         """Return the names of all the instances provisioned.
 
         :returns: a list of instance names.
+        :raises: VirtDriverNotReady
 
         """
         # NOTE(lucasagomes): limit == 0 is an indicator to continue
@@ -607,6 +611,7 @@ class IronicDriver(virt_driver.ComputeDriver):
         """Return the UUIDs of all the instances provisioned.
 
         :returns: a list of instance UUIDs.
+        :raises: VirtDriverNotReady
 
         """
         # NOTE(lucasagomes): limit == 0 is an indicator to continue