Allow empty container dicts in env overrides

When specifying an empty dictionary for a container, the component
should be skipped rather than being deployed. This change ensures that
the relevant keys are present in a container's dictionary before trying
to add it to the hierarchy.

As an example:

container_skel:
  nova_api_metadata_container: {}

Previously, if 'contains' or 'belongs_to' were missing keys, the script
would raise a KeyError.

Both 'contains' and 'belongs_to' keys can comprise of empty lists rather
than having them completely missing as another option for overrides.

The test classes for the overrides were split into base, unit, and
integration classes. Simply subclassing the integration tests from the
existing unit test class caused the test_* methods to be duplicated.
Thus, the supporting code for both was moved into a base class to reduce
code and execution duplication.

Change-Id: Iebecaaa0e1c0296d5289c050c6f7fc7ca6e71bef
Closes-Bug: #1600628

playbooks/inventory/dynamic_inventory.py

@@ -686,6 +686,9 @@ def container_skel_load(container_skel, inventory, config):
     :param config: ``dict``  User defined information
     """
     for key, value in container_skel.iteritems():
+        contains_in = value.get('contains', False)
+        belongs_to_in = value.get('belongs_to', False)
+        if contains_in or belongs_to_in:
             for assignment in value['contains']:
                 for container_type in value['belongs_to']:
                     _add_container_hosts(

tests/test_inventory.py

@@ -801,7 +801,7 @@ class TestEnsureInventoryUptoDate(unittest.TestCase):
         self.inv = None
 
 
-class TestOverridingEnvVars(unittest.TestCase):
+class OverridingEnvBase(unittest.TestCase):
     def setUp(self):
         self.base_env = di.load_environment(BASE_ENV_DIR, {})
 
@@ -816,6 +816,13 @@ class TestOverridingEnvVars(unittest.TestCase):
         with open(path.join(self.override_path, 'cinder.yml'), 'w') as f:
             f.write(yaml.safe_dump(self.cinder_config))
 
+    def tearDown(self):
+        os.remove(path.join(self.override_path, 'cinder.yml'))
+        os.rmdir(self.override_path)
+
+
+class TestOverridingEnvVars(OverridingEnvBase):
+
     def test_cinder_metal_override(self):
         vol = self.cinder_config['container_skel']['cinder_volumes_container']
         vol['properties']['is_metal'] = False
@@ -880,9 +887,83 @@ class TestOverridingEnvVars(unittest.TestCase):
 
         self.assertEqual(test_vol['belongs_to'], [])
 
+
+class TestOverridingEnvIntegration(OverridingEnvBase):
+    def setUp(self):
+        super(TestOverridingEnvIntegration, self).setUp()
+        self.user_defined_config = {}
+        with open(USER_CONFIG_FILE, 'rb') as f:
+            self.user_defined_config.update(yaml.safe_load(f.read()))
+
+        # Inventory is necessary since keys are assumed present
+        self.inv = di.get_inventory(TARGET_DIR, '')
+
+    def skel_setup(self):
+        self.environment = di.load_environment(TARGET_DIR, self.base_env)
+
+        di.skel_setup(self.environment, self.inv)
+
+        di.skel_load(
+            self.environment.get('physical_skel'),
+            self.inv
+        )
+
+    def test_emptying_container_integration(self):
+        self.cinder_config = {}
+        self.cinder_config['container_skel'] = {'cinder_volumes_container': {}}
+
+        self.write_override_env()
+        self.skel_setup()
+
+        di.container_skel_load(
+            self.environment.get('container_skel'),
+            self.inv,
+            self.user_defined_config
+        )
+
+        test_vol = self.base_env['container_skel']['cinder_volumes_container']
+
+        self.assertNotIn('belongs_to', test_vol)
+        self.assertNotIn('contains', test_vol)
+
+    def test_empty_contains(self):
+        vol = self.cinder_config['container_skel']['cinder_volumes_container']
+        vol['contains'] = []
+
+        self.write_override_env()
+        self.skel_setup()
+
+        di.container_skel_load(
+            self.environment.get('container_skel'),
+            self.inv,
+            self.user_defined_config
+        )
+
+        test_vol = self.base_env['container_skel']['cinder_volumes_container']
+
+        self.assertEqual(test_vol['contains'], [])
+
+    def test_empty_belongs_to(self):
+        vol = self.cinder_config['container_skel']['cinder_volumes_container']
+        vol['belongs_to'] = []
+
+        self.write_override_env()
+        self.skel_setup()
+
+        di.container_skel_load(
+            self.environment.get('container_skel'),
+            self.inv,
+            self.user_defined_config
+        )
+
+        test_vol = self.base_env['container_skel']['cinder_volumes_container']
+
+        self.assertEqual(test_vol['belongs_to'], [])
+
     def tearDown(self):
-        os.remove(path.join(self.override_path, 'cinder.yml'))
-        os.rmdir(self.override_path)
+        super(TestOverridingEnvIntegration, self).tearDown()
+        self.user_defined_config = None
+        self.inv = None
 
 if __name__ == '__main__':
     unittest.main()