Work around parameter error deleting backup stack

There is a problem where restoring a backup resource which references
a parameter in it's properties that doesn't exist in the backup stack
will fail to delete, if the property is referenced in the delete path
of the resource.

We can work around the problem by always returning the frozen_definition
properties on delete, provided there are stored properties to refer to.

Closes-Bug: #1494260
Change-Id: I462ce7161497306483286b78416f9037ac80d6fa

heat/engine/resource.py

@@ -1186,6 +1186,12 @@ class Resource(object):
 
         LOG.info(_LI('deleting %s'), six.text_type(self))
 
+        if self._stored_properties_data is not None:
+            # On delete we can't rely on re-resolving the properties
+            # so use the stored frozen_definition instead
+            self.properties = self.frozen_definition().properties(
+                self.properties_schema, self.context)
+
         with self._action_recorder(action):
             if self.abandon_in_progress:
                 deletion_policy = self.t.RETAIN

heat/tests/common.py

@@ -143,6 +143,8 @@ class HeatTestCase(testscenarios.WithScenarios,
                                  generic_rsrc.SignalResource)
         resource._register_class('ResourceWithPropsType',
                                  generic_rsrc.ResourceWithProps)
+        resource._register_class('ResourceWithPropsRefPropOnDelete',
+                                 generic_rsrc.ResourceWithPropsRefPropOnDelete)
         resource._register_class('StackUserResourceType',
                                  generic_rsrc.StackUserResource)
         resource._register_class('ResourceWithResourceIDType',

heat/tests/generic_resource.py

@@ -97,6 +97,11 @@ class ResourceWithProps(GenericResource):
         'FooInt': properties.Schema(properties.Schema.INTEGER)}
 
 
+class ResourceWithPropsRefPropOnDelete(ResourceWithProps):
+    def check_delete_complete(self, cookie):
+        return self.properties['FooInt'] is not None
+
+
 class ResourceWithPropsAndAttrs(ResourceWithProps):
     attributes_schema = {'Bar': attributes.Schema('Something.')}
 

heat/tests/test_stack_update.py

@@ -1695,13 +1695,15 @@ class StackUpdateTest(common.HeatTestCase):
 
         tmpl_update = {
             'heat_template_version': '2013-05-23',
+            'parameters': {'aparam': {'type': 'number', 'default': 1}},
             'resources': {
                 'Ares': {'type': 'GenericResourceType'},
                 'Bres': {'type': 'GenericResourceType'},
                 'Cres': {
-                    'type': 'ResourceWithPropsType',
+                    'type': 'ResourceWithPropsRefPropOnDelete',
                     'properties': {
                         'Foo': {'get_resource': 'Bres'},
+                        'FooInt': {'get_param': 'aparam'},
                     }
                 }
             }