Bypass ironic server not available issue

The ironic driver needs enhancement for exception handling.
This patch is a workaround to make devstack with ironic enabled
success. A more elegant patch should be made later in ironic
driver for exception handling.

Change-Id: Ibace25ad905a8278ecea4b02c69c59737a490d3a
Closes-Bug: #1430616

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

@@ -21,6 +21,7 @@ from oslo_config import cfg
 from oslo_serialization import jsonutils
 from oslo_utils import uuidutils
 import six
+from testtools.matchers import HasLength
 
 from nova.api.metadata import base as instance_metadata
 from nova.compute import power_state as nova_states
@@ -440,6 +441,15 @@ class IronicDriverTestCase(test.NoDBTestCase):
         self.assertEqual(['instance-00000000', 'instance-00000001'],
                           sorted(response))
 
+    @mock.patch.object(cw.IronicClientWrapper, 'call')
+    @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()
+        mock_call.assert_called_with("node.list", associated=True, limit=0)
+        self.assertFalse(mock_inst_by_uuid.called)
+        self.assertThat(response, HasLength(0))
+
     @mock.patch.object(cw.IronicClientWrapper, 'call')
     def test_list_instance_uuids(self, mock_call):
         num_nodes = 2

nova/virt/ironic/driver.py

@@ -435,6 +435,20 @@ class IronicDriver(virt_driver.ComputeDriver):
         except exception.InstanceNotFound:
             return False
 
+    def _get_node_list(self, **kwargs):
+        """Helper function to return the list of nodes.
+
+        If unable to connect ironic server, an empty list is returned.
+
+        :returns: a list of raw node from ironic
+
+        """
+        try:
+            node_list = self.ironicclient.call("node.list", **kwargs)
+        except exception.NovaException:
+            node_list = []
+        return node_list
+
     def list_instances(self):
         """Return the names of all the instances provisioned.
 
@@ -443,8 +457,7 @@ class IronicDriver(virt_driver.ComputeDriver):
         """
         # NOTE(lucasagomes): limit == 0 is an indicator to continue
         # pagination until there're no more values to be returned.
-        node_list = self.ironicclient.call("node.list", associated=True,
-                                           limit=0)
+        node_list = self._get_node_list(associated=True, limit=0)
         context = nova_context.get_admin_context()
         return [objects.Instance.get_by_uuid(context,
                                              i.instance_uuid).name
@@ -458,9 +471,8 @@ class IronicDriver(virt_driver.ComputeDriver):
         """
         # NOTE(lucasagomes): limit == 0 is an indicator to continue
         # pagination until there're no more values to be returned.
-        node_list = self.ironicclient.call("node.list", associated=True,
-                                           limit=0)
-        return list(n.instance_uuid for n in node_list)
+        return list(n.instance_uuid
+                    for n in self._get_node_list(associated=True, limit=0))
 
     def node_is_available(self, nodename):
         """Confirms a Nova hypervisor node exists in the Ironic inventory.
@@ -492,9 +504,8 @@ class IronicDriver(virt_driver.ComputeDriver):
     def _refresh_cache(self):
         # NOTE(lucasagomes): limit == 0 is an indicator to continue
         # pagination until there're no more values to be returned.
-        node_list = self.ironicclient.call('node.list', detail=True, limit=0)
         node_cache = {}
-        for node in node_list:
+        for node in self._get_node_list(detail=True, limit=0):
             node_cache[node.uuid] = node
         self.node_cache = node_cache
         self.node_cache_time = time.time()