Forbid removing portgroup mode

Mode can be left empty on creation, the value will be populated by
the dbapi, but in case of updates, we should not allow removing it.

Partial-Bug: #1618754
Change-Id: I917b23bc155972b777b143d16545a49039604910

ironic/api/controllers/v1/portgroup.py

@@ -188,6 +188,7 @@ class Portgroup(base.APIBase):
 class PortgroupPatchType(types.JsonPatchType):
 
     _api_base = Portgroup
+    _extra_non_removable_attrs = {'/mode'}
 
     @staticmethod
     def internal_attrs():

ironic/tests/unit/api/v1/test_portgroups.py

@@ -852,10 +852,21 @@ class TestPatch(test_api_base.BaseApiTest):
 
     def test_update_portgroup_mode_properties_bad_api_version(self, mock_upd):
         self._test_update_portgroup_mode_properties_bad_api_version(
-            [{'path': '/mode', 'op': 'remove'}], mock_upd)
+            [{'path': '/mode', 'op': 'add', 'value': '802.3ad'}], mock_upd)
         self._test_update_portgroup_mode_properties_bad_api_version(
             [{'path': '/properties/abc', 'op': 'add', 'value': 123}], mock_upd)
 
+    def test_remove_mode_not_allowed(self, mock_upd):
+        response = self.patch_json('/portgroups/%s' % self.portgroup.uuid,
+                                   [{'path': '/mode',
+                                     'op': 'remove'}],
+                                   expect_errors=True,
+                                   headers=self.headers)
+        self.assertEqual(http_client.BAD_REQUEST, response.status_int)
+        self.assertEqual('application/json', response.content_type)
+        self.assertTrue(response.json['error_message'])
+        self.assertFalse(mock_upd.called)
+
 
 class TestPost(test_api_base.BaseApiTest):
     headers = {api_base.Version.string: str(api_v1.MAX_VER)}

releasenotes/notes/add-portgroup-config-fields-cd21e35e9c210733.yaml

@@ -1,8 +1,9 @@
 ---
 features:
   - Adds ``mode`` and ``properties`` fields in the portgroup object. Both of
-    them are optional and can be set from the API. They are available starting
-    with API microversion 1.26. If the ``mode`` field of a portgroup is not
+    them are optional and can be set from the API, though it is forbidden to
+    remove the ``mode`` from the portgroup. They are available starting with
+    API microversion 1.26. If the ``mode`` field of a portgroup is not
     specified in a POST request, its value will be set to the value of the
     configuration option ``[DEFAULT]default_portgroup_mode``. The configuration
     option ``[DEFAULT]default_portgroup_mode`` has a value of ``active-backup``