Fix KeyError exception when stack snapshot deletion

There is no 'backup_id' data in snapshot if the cinder
volume snapshot failed. This patch will use 'get'
instead __getitem__ to get the 'backup_id' data to avoid
KeyError exception raise.

Change-Id: Iae7e22ccdaf8f48a85d90afac3a38011f14cbd34
Closes-Bug: #1465173

heat/engine/resources/openstack/cinder/volume.py

@@ -394,7 +394,9 @@ class CinderVolume(vb.BaseVolume):
         raise exception.Error(backup.fail_reason)
 
     def handle_delete_snapshot(self, snapshot):
-        backup_id = snapshot['resource_data']['backup_id']
+        backup_id = snapshot['resource_data'].get('backup_id')
+        if not backup_id:
+            return
         try:
             self.client().backups.delete(backup_id)
         except Exception as ex:

heat/tests/openstack/test_volume.py

@@ -22,6 +22,7 @@ from heat.common import exception
 from heat.common import template_format
 from heat.engine.clients.os import cinder
 from heat.engine.clients.os import glance
+from heat.engine.resources.openstack.cinder import volume as c_vol
 from heat.engine import rsrc_defn
 from heat.engine import scheduler
 from heat.objects import resource_data as resource_data_object
@@ -1044,3 +1045,16 @@ class CinderVolumeTest(vt_base.BaseVolumeTest):
         self.assertEqual((stack.RESTORE, stack.COMPLETE), stack.state)
 
         self.m.VerifyAll()
+
+    def test_handle_delete_snapshot_no_backup(self):
+        stack_name = 'test_handle_delete_snapshot_no_backup'
+        mock_vs = {
+            'resource_data': {}
+        }
+        t = template_format.parse(single_cinder_volume_template)
+        stack = utils.parse_stack(t, stack_name=stack_name)
+        rsrc = c_vol.CinderVolume(
+            'volume',
+            stack.t.resource_definitions(stack)['volume'],
+            stack)
+        self.assertIsNone(rsrc.handle_delete_snapshot(mock_vs))