ResourceGroup allow update of resource_def

Currently the group is replaced if the resource_def is updated,
but instead we should allow updates and update the underlying
nested stack instead.  This allows properties to be changed
such that non-replacement updates can be performed on the
resource-group members.

Change-Id: I471b7ebe71ed262a8b0e2c971a32afc7062699cb
Closes-Bug: #1396533
Closes-Bug: #1380612
(cherry picked from commit d5c84e5defdaccf6292ad154641a1197f827a949)

2 files changed, 23 insertions, 1 deletions

diff --git a/heat/engine/resources/resource_group.py b/heat/engine/resources/resource_group.py
index f4f0d8dfe..158f34091 100644
--- a/heat/engine/resources/resource_group.py
+++ b/heat/engine/resources/resource_group.py
@@ -121,7 +121,8 @@ class ResourceGroup(stack_resource.StackResource):
                     _('Property values for the resources in the group')
                 ),
             },
-            required=True
+            required=True,
+            update_allowed=True
         ),
     }
 
diff --git a/heat/tests/test_resource_group.py b/heat/tests/test_resource_group.py
index 2346747d9..ce22a4715 100644
--- a/heat/tests/test_resource_group.py
+++ b/heat/tests/test_resource_group.py
@@ -379,6 +379,27 @@ class ResourceGroupTest(common.HeatTestCase):
         self.assertEqual((resg.UPDATE, resg.COMPLETE), resg.nested().state)
         self.assertEqual(3, len(resg.nested()))
 
+    def test_props_update(self):
+        """Test update of resource_def properties."""
+        resg = self._create_dummy_stack()
+        self.assertEqual(2, len(resg.nested()))
+        resource_names = [r.name for r in resg.nested().iter_resources()]
+        self.assertEqual(['0', '1'], sorted(resource_names))
+        new_snip = copy.deepcopy(resg.t)
+        new_snip['Properties']['resource_def']['properties']['Foo'] = 'xyz'
+        preupdate_resgid = resg.id
+        preupdate_nestedid = resg.nested().id
+        scheduler.TaskRunner(resg.update, new_snip)()
+        self.stack = resg.nested()
+        self.assertEqual((resg.UPDATE, resg.COMPLETE), resg.state)
+        self.assertEqual((resg.UPDATE, resg.COMPLETE), resg.nested().state)
+        self.assertEqual(2, len(resg.nested()))
+        resource_names = [r.name for r in resg.nested().iter_resources()]
+        self.assertEqual(['0', '1'], sorted(resource_names))
+        # resource_def update should recurse and update (not replace) nested
+        self.assertEqual(preupdate_resgid, resg.id)
+        self.assertEqual(preupdate_nestedid, resg.nested().id)
+
     def test_update_nochange(self):
         """Test update with no properties change."""
         resg = self._create_dummy_stack()