Fix lp:844155

When using an abstract scheduler class, if no compute hosts are available locally, the checking of child zones is short circuited.  I've removed the broken check.

2 files changed, 22 insertions, 3 deletions

diff --git a/nova/scheduler/abstract_scheduler.py b/nova/scheduler/abstract_scheduler.py
index 7f17b642f..cb8db599f 100644
--- a/nova/scheduler/abstract_scheduler.py
+++ b/nova/scheduler/abstract_scheduler.py
@@ -269,9 +269,6 @@ class AbstractScheduler(driver.Scheduler):
         # Filter local hosts based on requirements ...
         filtered_hosts = self.filter_hosts(topic, request_spec,
                 unfiltered_hosts)
-        if not filtered_hosts:
-            LOG.warn(_("No hosts available"))
-            return []
 
         # weigh the selected hosts.
         # weighted_hosts = [{weight=weight, hostname=hostname,
diff --git a/nova/tests/scheduler/test_abstract_scheduler.py b/nova/tests/scheduler/test_abstract_scheduler.py
index 9bf128b13..5549ea453 100644
--- a/nova/tests/scheduler/test_abstract_scheduler.py
+++ b/nova/tests/scheduler/test_abstract_scheduler.py
@@ -372,6 +372,28 @@ class AbstractSchedulerTestCase(test.TestCase):
         self.assertEqual(fixture._decrypt_blob(test_data),
                          json.dumps(test_data))
 
+    def test_empty_local_hosts(self):
+        """
+        Create a nested set of FakeZones, try to build multiple instances
+        and ensure that a select call returns the appropriate build plan.
+        """
+        sched = FakeAbstractScheduler()
+        self.stubs.Set(sched, '_call_zone_method', fake_call_zone_method)
+        self.stubs.Set(nova.db, 'zone_get_all', fake_zone_get_all)
+
+        zm = FakeZoneManager()
+        # patch this to have no local hosts
+        zm.service_states = {}
+        sched.set_zone_manager(zm)
+
+        fake_context = {}
+        build_plan = sched.select(fake_context,
+                {'instance_type': {'memory_mb': 512},
+                    'num_instances': 4})
+
+        # 0 from local zones, 12 from remotes
+        self.assertEqual(12, len(build_plan))
+
 
 class BaseSchedulerTestCase(test.TestCase):
     """Test case for Base Scheduler."""