Add standard attributes to segment resource

Standard attributes (i.e. revision_number, created_at, updated_at)
are missing in the segment resource. This is because the controller
doesn't process extensions on rendering the response. This patch
fixes it. In particular, this patch does the following:
* Process extensions when making the segment dict. This allows
  other extensions to add attributes to segment response.
* Make segment extension implement update_attributes_map.

Tempest test: https://review.openstack.org/#/c/558609/

APIImpact update api reference of segments

Closes-Bug: #1760902
Change-Id: I3c93818002c2d7753454547231ba08544b6fa1c0

neutron/extensions/segment.py

@@ -122,6 +122,10 @@ class Segment(api_extensions.ExtensionDescriptor):
                                              controller,
                                              attr_map=resource_attributes)]
 
+    def update_attributes_map(self, attributes):
+        super(Segment, self).update_attributes_map(
+            attributes, extension_attrs_map=RESOURCE_ATTRIBUTE_MAP)
+
     def get_extended_resources(self, version):
         if version == "2.0":
             return RESOURCE_ATTRIBUTE_MAP

neutron/services/segments/db.py

@@ -25,6 +25,7 @@ from oslo_db import exception as db_exc
 from oslo_log import helpers as log_helpers
 from oslo_utils import uuidutils
 
+from neutron.db import _resource_extend as resource_extend
 from neutron.db import _utils as db_utils
 from neutron.db import api as db_api
 from neutron.db import common_db_mixin
@@ -50,6 +51,7 @@ class SegmentDbMixin(common_db_mixin.CommonDbMixin):
                db.SEGMENTATION_ID: segment_obj[db.SEGMENTATION_ID],
                'hosts': segment_obj['hosts'],
                'segment_index': segment_obj['segment_index']}
+        resource_extend.apply_funcs('segments', res, segment_obj.db_obj)
         return db_utils.resource_fields(res, fields)
 
     def _get_segment(self, context, segment_id):

releasenotes/notes/add-standard-attributes-to-segment-d39c4b89988aa701.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fix an issue that standard attributes, such as ``created_at``,
+    ``updated_at`` and ``revision_number``, are not rendered in the response
+    of segment resource.