Delete previous template upon update

During stack update, we flip the stack raw_template a number of times.
In case of success, we leave the old active raw_template row unlinked to
anything, so it needs to be deleted. This patch does so.

Change-Id: I6f3ff5bfbac417e3bd6032cabfbc00bd6dec8b02
Closes-Bug: #1506077

heat/engine/stack.py

@@ -1186,6 +1186,7 @@ class Stack(collections.Mapping):
         backup_stack = self._backup_stack()
         existing_params = environment.Environment({env_fmt.PARAMETERS:
                                                   self.t.env.params})
+        previous_template_id = None
         try:
             update_task = update.StackUpdate(
                 self, newstack, backup_stack,
@@ -1239,6 +1240,7 @@ class Stack(collections.Mapping):
             backup_stack.delete(backup=True)
 
             # flip the template to the newstack values
+            previous_template_id = self.t.id
             self.t = newstack.t
             template_outputs = self.t[self.t.OUTPUTS]
             self.outputs = self.resolve_static_data(template_outputs)
@@ -1257,6 +1259,10 @@ class Stack(collections.Mapping):
             self.t.store(self.context)
         self.store()
 
+        if previous_template_id is not None:
+            raw_template_object.RawTemplate.delete(self.context,
+                                                   previous_template_id)
+
         lifecycle_plugin_utils.do_post_ops(self.context, self,
                                            newstack, action,
                                            (self.status == self.FAILED))

heat/tests/test_stack_update.py

@@ -17,6 +17,7 @@ import mock
 
 from heat.common import exception
 from heat.common import template_format
+from heat.db.sqlalchemy import api as db_api
 from heat.engine import environment
 from heat.engine import resource
 from heat.engine import scheduler
@@ -50,6 +51,7 @@ class StackUpdateTest(common.HeatTestCase):
                                  template.Template(tmpl))
         self.stack.store()
         self.stack.create()
+        raw_template_id = self.stack.t.id
         self.assertEqual((stack.Stack.CREATE, stack.Stack.COMPLETE),
                          self.stack.state)
 
@@ -63,6 +65,10 @@ class StackUpdateTest(common.HeatTestCase):
         self.assertEqual((stack.Stack.UPDATE, stack.Stack.COMPLETE),
                          self.stack.state)
         self.assertIn('BResource', self.stack)
+        self.assertNotEqual(raw_template_id, self.stack.t.id)
+        self.assertNotEqual(raw_template_id, self.stack.prev_raw_template_id)
+        self.assertRaises(exception.NotFound,
+                          db_api.raw_template_get, self.ctx, raw_template_id)
 
     def test_update_remove(self):
         tmpl = {'HeatTemplateFormatVersion': '2012-12-12',
@@ -859,8 +865,9 @@ class StackUpdateTest(common.HeatTestCase):
         mock_create = self.patchobject(generic_rsrc.ResourceWithProps,
                                        'handle_create', side_effect=Exception)
 
-        with mock.patch.object(stack_object.Stack,
-                               'update_by_id') as mock_db_update:
+        with mock.patch.object(
+                stack_object.Stack, 'update_by_id',
+                wraps=stack_object.Stack.update_by_id) as mock_db_update:
             self.stack.update(updated_stack)
             self.assertEqual((stack.Stack.ROLLBACK, stack.Stack.COMPLETE),
                              self.stack.state)