Avoid KeyError Exception in extract_flavor()

In the function extract_flavor(), if the returned sys_meta
of the instance is empty dict or does not exist then the function
is returned to avoid KeyError Exception.

Change-Id: Ic996cc0ca0303772c4e6a8bbb9f4165ddcdfafff
Closes-Bug: #1226083

nova/compute/flavors.py

@@ -278,6 +278,10 @@ def extract_flavor(instance, prefix=''):
 
     flavor = objects.Flavor()
     sys_meta = utils.instance_sys_meta(instance)
+
+    if not sys_meta:
+        return None
+
     for key in system_metadata_flavor_props.keys():
         type_key = '%sinstance_type_%s' % (prefix, key)
         setattr(flavor, key, sys_meta[type_key])

nova/compute/resource_tracker.py

@@ -248,7 +248,8 @@ class ResourceTracker(object):
                 image_meta = utils.get_image_from_system_metadata(
                         instance['system_metadata'])
 
-            if instance_type['id'] == itype['id']:
+            if (instance_type is not None and
+                instance_type['id'] == itype['id']):
                 numa_topology = hardware.numa_get_constraints(
                     itype, image_meta)
                 usage = self._get_usage_dict(

nova/tests/unit/test_flavors.py

@@ -279,6 +279,13 @@ class InstanceTypeToolsTest(test.TestCase):
     def test_extract_flavor(self):
         self._test_extract_flavor('')
 
+    def test_extract_flavor_no_sysmeta(self):
+        instance = {}
+        prefix = ''
+        result = flavors.extract_flavor(instance, prefix)
+
+        self.assertIsNone(result)
+
     def test_extract_flavor_prefix(self):
         self._test_extract_flavor('foo_')