Restore resource metadata attribute

For backwards compatibility the Resource.metadata attribute
has been restored, however reading or assigning this attribute
will result in a deprecation warning.

Reading metadata will force a refresh from the database, which
maintains the previous behaviour rather than optimising for
performance.

Change-Id: Ifdcf3d98b99a09aac8755c84ef3f59d8602fc6a8
Closes-Bug: #1324704

heat/engine/resource.py

@@ -14,8 +14,8 @@
 import base64
 import copy
 from datetime import datetime
-
 import six
+import warnings
 
 from heat.common import exception
 from heat.common import identifier
@@ -175,6 +175,22 @@ class Resource(object):
             return result
         return not result
 
+    @property
+    def metadata(self):
+        """DEPRECATED. use method metadata_get instead."""
+        warnings.warn('metadata attribute is deprecated, '
+                      'use method metadata_get instead',
+                      DeprecationWarning)
+        return self.metadata_get(True)
+
+    @metadata.setter
+    def metadata(self, metadata):
+        """DEPRECATED. use method metadata_set instead."""
+        warnings.warn('metadata attribute is deprecated, '
+                      'use method metadata_set instead',
+                      DeprecationWarning)
+        self.metadata_set(metadata)
+
     def metadata_get(self, refresh=False):
         if refresh:
             self._rsrc_metadata = None

heat/tests/test_resource.py

@@ -305,6 +305,7 @@ class ResourceTest(HeatTestCase):
         tmpl = {'Type': 'Foo'}
         res = generic_rsrc.GenericResource('test_resource', tmpl, self.stack)
         self.assertEqual({}, res.metadata_get())
+        self.assertEqual({}, res.metadata)
 
     def test_equals_different_stacks(self):
         tmpl1 = {'Type': 'Foo'}
@@ -761,6 +762,7 @@ class ResourceAdoptTest(HeatTestCase):
         adopt = scheduler.TaskRunner(res.adopt, res_data)
         adopt()
         self.assertEqual({}, res.metadata_get())
+        self.assertEqual({}, res.metadata)
         self.assertEqual((res.ADOPT, res.COMPLETE), res.state)
 
     def test_adopt_with_resource_data_and_metadata(self):
@@ -790,6 +792,7 @@ class ResourceAdoptTest(HeatTestCase):
         self.assertEqual("test-value",
                          db_api.resource_data_get(res, "test-key"))
         self.assertEqual({"os_distro": "test-distro"}, res.metadata_get())
+        self.assertEqual({"os_distro": "test-distro"}, res.metadata)
         self.assertEqual((res.ADOPT, res.COMPLETE), res.state)
 
     def test_adopt_resource_missing(self):
@@ -1309,12 +1312,19 @@ class MetadataTest(HeatTestCase):
 
     def test_read_initial(self):
         self.assertEqual({'Test': 'Initial metadata'}, self.res.metadata_get())
+        self.assertEqual({'Test': 'Initial metadata'}, self.res.metadata)
 
     def test_write(self):
         test_data = {'Test': 'Newly-written data'}
         self.res.metadata_set(test_data)
         self.assertEqual(test_data, self.res.metadata_get())
 
+    def test_assign_attribute(self):
+        test_data = {'Test': 'Newly-written data'}
+        self.res.metadata = test_data
+        self.assertEqual(test_data, self.res.metadata_get())
+        self.assertEqual(test_data, self.res.metadata)
+
 
 class ReducePhysicalResourceNameTest(HeatTestCase):
     scenarios = [