Add AZ resource metadata for volume size polling

Change-Id: I18c2a212a3f4c3ebb55c882c403ac4c374596657

ceilometer/tests/unit/volume/test_cinder.py

@@ -148,6 +148,8 @@ class TestVolumeSizePollster(base.BaseTestCase):
         self.assertEqual('1ae69721-d071-4156-a2bd-b11bb43ec2e3',
                          volume_size_samples[0].resource_metadata
                          ["instance_id"])
+        self.assertEqual('nova', volume_size_samples[0].resource_metadata
+                         ["availability_zone"])
 
 
 class TestVolumeSnapshotSizePollster(base.BaseTestCase):

ceilometer/volume/cinder.py

@@ -39,6 +39,7 @@ class VolumeSizePollster(_Base):
     FIELDS = ['name',
               'status',
               'volume_type',
+              'availability_zone',
               'os-vol-host-attr:host',
               'migration_status',
               'attachments',

releasenotes/notes/cinder-volume-size-poller-availability_zone-2d20a7527e2341b9.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    The resource metadata for the Cinder volume size poller now includes
+    the availability zone field.