LaunchConfiguration replace on changed Metadata

This makes AWS::AutoScaling::LaunchConfiguration raise
an UpdateReplace if its template Metadata is changed on a
stack update. Any changes to LaunchConfiguration should result
in the resource being replaced, since this is how those changes
propagate to the scaling group.

This fixes a regression which has likely existed since
update_allowed_keys was removed: I78494aba07b6badeca8e95f1875ca8e4b9b0290c

Change-Id: I3a53422ed862777dffb9cac28088fbfe8dd417fa
Closes-Bug: #1287953

heat/engine/resources/autoscaling.py

@@ -824,6 +824,10 @@ class LaunchConfiguration(resource.Resource):
         ),
     }
 
+    def handle_update(self, json_snippet, tmpl_diff, prop_diff):
+        if 'Metadata' in tmpl_diff:
+            raise resource.UpdateReplace(self.name)
+
     def FnGetRefId(self):
         return unicode(self.physical_resource_name())
 

heat/tests/test_instance_group.py

@@ -46,6 +46,7 @@ ig_template = '''
 
     "JobServerConfig" : {
       "Type" : "AWS::AutoScaling::LaunchConfiguration",
+      "Metadata": {"foo": "bar"},
       "Properties": {
         "ImageId"           : "foo",
         "InstanceType"      : "m1.large",
@@ -327,3 +328,36 @@ class InstanceGroupTest(HeatTestCase):
 
         rsrc.delete()
         self.m.VerifyAll()
+
+    def test_update_config_metadata(self):
+        t = template_format.parse(ig_template)
+        properties = t['Resources']['JobServerGroup']['Properties']
+        properties['Size'] = '2'
+        stack = utils.parse_stack(t)
+
+        self._stub_create(2)
+        self.m.ReplayAll()
+        rsrc = self.create_resource(t, stack, 'JobServerConfig')
+        self.create_resource(t, stack, 'JobServerGroup')
+
+        props = copy.copy(rsrc.properties.data)
+        metadata = copy.copy(rsrc.metadata_get())
+
+        update_snippet = rsrc_defn.ResourceDefinition(rsrc.name,
+                                                      rsrc.type(),
+                                                      props,
+                                                      metadata)
+        # Change nothing in the first update
+        scheduler.TaskRunner(rsrc.update, update_snippet)()
+
+        self.assertEqual('bar', metadata['foo'])
+        metadata['foo'] = 'wibble'
+        update_snippet = rsrc_defn.ResourceDefinition(rsrc.name,
+                                                      rsrc.type(),
+                                                      props,
+                                                      metadata)
+        # Changing metadata in the second update triggers UpdateReplace
+        updater = scheduler.TaskRunner(rsrc.update, update_snippet)
+        self.assertRaises(resource.UpdateReplace, updater)
+
+        self.m.VerifyAll()