Updates keystone region constraints for endpoint

OS::Keystone::Endpoint region property is updated to
validate with keystone.region

implements blueprint: heat-keystone-region-resource

Change-Id: I4bc75c428d10376711d3852d240e4da6e46f36cc

heat/engine/resources/openstack/keystone/endpoint.py

@@ -44,7 +44,8 @@ class KeystoneEndpoint(resource.Resource):
         REGION: properties.Schema(
             properties.Schema.STRING,
             _('Name or Id of keystone region.'),
-            update_allowed=True
+            update_allowed=True,
+            constraints=[constraints.CustomConstraint('keystone.region')]
         ),
         SERVICE: properties.Schema(
             properties.Schema.STRING,

heat/tests/openstack/keystone/test_endpoint.py

@@ -266,6 +266,14 @@ class KeystoneEndpointTest(common.HeatTestCase):
                          'description for property %s is modified' %
                          endpoint.KeystoneEndpoint.REGION)
 
+        # Make sure, REGION is of keystone.region custom constraint type
+        self.assertEqual(1, len(schema.constraints))
+        keystone_region_constraint = schema.constraints[0]
+        self.assertIsInstance(keystone_region_constraint,
+                              constraints.CustomConstraint)
+        self.assertEqual('keystone.region',
+                         keystone_region_constraint.name)
+
     def test_property_interface_validate_schema(self):
         schema = (endpoint.KeystoneEndpoint.properties_schema[
                   endpoint.KeystoneEndpoint.INTERFACE])