cfn - stack ensure present - catch DELETE_FAILED state (#479)

* cfn - stack ensure present - catch DELETE_FAILED state

* add test_update_stack_in_delete_failed_state

kingpin/actors/aws/cloudformation.py

@@ -838,6 +838,14 @@ def __init__(self, *args, **kwargs):
     def _update_stack(self, stack):
         self.log.info('Verifying that stack is in desired state')
 
+        # First, check that this stack isn't one that may have failed before
+        # and there was attempted to be deleted but failed. If it is, we have a
+        # fatal error and we must raise an exception.
+        if stack['StackStatus'] == 'DELETE_FAILED':
+            msg = 'Stack found in a deleted failed state: %s' % (
+                stack['StackStatus'])
+            raise StackFailed(msg)
+
         # Upon a stack creation, there are two states the stack can be left in
         # that are both un-fixable -- CREATE_FAILED and ROLLBACK_COMPLETE. In
         # both of these cases, the only possible option is to destroy the stack

kingpin/actors/aws/test/test_cloudformation.py

@@ -710,6 +710,13 @@ def test_update_stack_in_failed_state(self):
         self.actor._create_stack.assert_called_with(
             stack='fake')
 
+    @testing.gen_test
+    def test_update_stack_in_delete_failed_state(self):
+        fake_stack = create_fake_stack('fake', 'DELETE_FAILED')
+        self.actor._get_stack = mock.MagicMock(name='_get_stack')
+        with self.assertRaises(cloudformation.StackFailed):
+            yield self.actor._update_stack(fake_stack)
+
     @testing.gen_test
     def test_update_stack_ensure_template(self):
         fake_stack = create_fake_stack('fake', 'CREATE_COMPLETE')