Conditionally make neutron-plugin relations required

When charm is not managing the plugin the neutron-plugin-* relations
should be required.

Change-Id: I8c061f272e68b05b6d415e0686564bd7f617aa12

hooks/neutron_api_context.py

@@ -696,7 +696,7 @@ class EtcdContext(context.OSContextGenerator):
 
 
 class NeutronApiSDNContext(context.SubordinateConfigContext):
-    interfaces = 'neutron-plugin-api-subordinate'
+    interfaces = ['neutron-plugin-api-subordinate']
 
     def __init__(self, config_file='/etc/neutron/neutron.conf'):
         """Initialize context for plugin subordinates.
@@ -807,7 +807,10 @@ class NeutronApiSDNContext(context.SubordinateConfigContext):
                         # Do not set empty values
                         pass
                 return ctxt
-        return ctxt
+        # Return empty dict when there are no related units, this will flag the
+        # context as incomplete and will allow end user messaging of missing
+        # relations
+        return {}
 
 
 class NeutronApiSDNConfigFileContext(context.OSContextGenerator):
@@ -820,7 +823,12 @@ class NeutronApiSDNConfigFileContext(context.OSContextGenerator):
                 neutron_server_plugin_conf = rdata.get('neutron-plugin-config')
                 if neutron_server_plugin_conf:
                     return {'config': neutron_server_plugin_conf}
-        return {'config': '/etc/neutron/plugins/ml2/ml2_conf.ini'}
+                else:
+                    return {'config': '/etc/neutron/plugins/ml2/ml2_conf.ini'}
+        # Return empty dict when there are no related units, this will flag the
+        # context as incomplete and will allow end user messaging of missing
+        # relations
+        return {}
 
 
 class NeutronApiApiPasteContext(context.OSContextGenerator):

hooks/neutron_api_utils.py

@@ -896,6 +896,11 @@ def get_optional_interfaces():
     optional_interfaces = {}
     if relation_ids('ha'):
         optional_interfaces['ha'] = ['cluster']
+    if not manage_plugin():
+        optional_interfaces['neutron-plugin'] = [
+            'neutron-plugin-api',
+            'neutron-plugin-api-subordinate',
+        ]
     return optional_interfaces
 
 

unit_tests/test_neutron_api_context.py

@@ -1204,7 +1204,7 @@ class NeutronApiSDNContextTest(CharmTestCase):
     def test_empty(self):
         self.ctxt_check(
             {},
-            {'sections': {}},
+            {},
         )
 
     def test_is_allowed(self):
@@ -1235,12 +1235,18 @@ class NeutronApiSDNConfigFileContextTest(CharmTestCase):
         })
 
     def test_default(self):
-        self.relation_ids.return_value = []
+        self.relation_ids.return_value = ['rid3']
+        self.related_units.return_value = ['unit2']
         napisdn_ctxt = context.NeutronApiSDNConfigFileContext()()
         self.assertEqual(napisdn_ctxt, {
             'config': '/etc/neutron/plugins/ml2/ml2_conf.ini'
         })
 
+    def test_no_related_unites(self):
+        self.relation_ids.return_value = ['rid4']
+        napisdn_ctxt = context.NeutronApiSDNConfigFileContext()()
+        self.assertEqual(napisdn_ctxt, {})
+
 
 class NeutronApiApiPasteContextTest(CharmTestCase):
 

unit_tests/test_neutron_api_utils.py

@@ -979,6 +979,25 @@ class TestNeutronAPIUtils(CharmTestCase):
             "?ssl_ca=foo&ssl_cert=bar&ssl_key=baz"
         )
 
+    @patch.object(nutils, 'manage_plugin')
+    @patch.object(nutils, 'relation_ids')
+    def test_get_optional_interfaces(self, mock_relation_ids,
+                                     mock_manage_plugin):
+        mock_relation_ids.return_value = False
+        mock_manage_plugin.return_value = True
+        self.assertDictEqual(nutils.get_optional_interfaces(), {})
+        mock_relation_ids.assert_called_once_with('ha')
+        mock_manage_plugin.assert_called_once_with()
+        mock_relation_ids.return_value = True
+        mock_manage_plugin.return_value = False
+        self.assertDictEqual(nutils.get_optional_interfaces(), {
+            'ha': ['cluster'],
+            'neutron-plugin': [
+                'neutron-plugin-api',
+                'neutron-plugin-api-subordinate',
+            ],
+        })
+
     @patch.object(nutils, 'config')
     @patch.object(nutils, 'relation_ids')
     @patch.object(nutils, 'log')