Handle None value for RoleConfig

RoleConfig can exist as a stack output, but have a value of None. That
case should be handled with a default value of {} where the value was
previously None.

Change-Id: I3caf31c00ab8c47d71a68eb82114fb398a47961b
Closes-Bug: #1748482

releasenotes/notes/role-config-none-d440bd0dcbb63534.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - RoleConfig can exist as a stack output, but have a value of None. That case
+    is now handled with a default value of {} where the value was previously
+    None.

tripleo_common/tests/utils/test_config.py

@@ -170,6 +170,13 @@ class TestConfig(base.TestCase):
         expected = {'2af0a373': 'c1', '8269f736': 'c0', 'c8479674': 'c2'}
         self.assertEqual(expected, server_names)
 
+    def test_get_role_config(self):
+        heat = mock.MagicMock()
+        self.config = ooo_config.Config(heat)
+        self.config.stack_outputs = {'RoleConfig': None}
+        role_config = self.config.get_role_config()
+        self.assertEqual({}, role_config)
+
     def test_get_deployment_data(self):
         heat = mock.MagicMock()
         self.config = ooo_config.Config(heat)

tripleo_common/utils/config.py

@@ -95,6 +95,11 @@ class Config(object):
         env.trim_blocks = True
         return env, templates_path
 
+    def get_role_config(self):
+        role_config = self.stack_outputs.get('RoleConfig', {})
+        # RoleConfig can exist as a stack output but have a value of None
+        return role_config or {}
+
     @staticmethod
     def _open_file(path):
         return os.fdopen(os.open(path,
@@ -180,7 +185,7 @@ class Config(object):
                         yaml.safe_dump(data,
                                        conf_file,
                                        default_flow_style=False)
-        role_config = self.stack_outputs.get('RoleConfig', {})
+        role_config = self.get_role_config()
         for config_name, config in six.iteritems(role_config):
             conf_path = os.path.join(tmp_path, config_name + ".yaml")
             with self._open_file(conf_path) as conf_file: