Normalise format of OVN agent heartbeat timestamp

A recent change [1] to show the real heartbeat timestamp from OVN agents
had a side effect of changing the timestamp format, which now includes a
timezone:

    +-------------------+----------------------------------+
    | Field             | Value                            |
    +-------------------+----------------------------------+
    | last_heartbeat_at | 2023-02-23 14:12:07.471000+00:00 |
    +-------------------+----------------------------------+

This unexpected format change causes some clients to fail to parse the
response to GET /v2.0/agents.

Normalise the format of the timestamp to remove timezone information.
Also remove the microsecond part, which was not done for OVN, but is
absent from other network agents.

[1] https://review.opendev.org/c/openstack/neutron/+/844179

Closes-Bug: #2008257
Change-Id: I75a37fb9b49a421e4524da6b56ef8362ceb6107b

neutron/plugins/ml2/drivers/ovn/agent/neutron_agent.py

@@ -81,7 +81,8 @@ class NeutronAgent(abc.ABC):
         return {
             'binary': self.binary,
             'host': self.chassis.hostname,
-            'heartbeat_timestamp': self.updated_at,
+            'heartbeat_timestamp': timeutils.normalize_time(
+                self.updated_at.replace(microsecond=0)),
             'availability_zone': ', '.join(
                 ovn_utils.get_chassis_availability_zones(self.chassis)),
             'topic': 'n/a',

neutron/tests/functional/plugins/ml2/drivers/ovn/mech_driver/test_mech_driver.py

@@ -1148,7 +1148,7 @@ class TestAgentApi(base.TestOVNFunctionalBase):
                 'Chassis_Private', self.chassis, 'nb_cfg_timestamp'
             ).execute(check_error=True)
             updated_at = datetime.datetime.fromtimestamp(
-                int(chassis_ts / 1000), datetime.timezone.utc)
+                int(chassis_ts / 1000))
             # if table Chassis_Private present, agent.updated_at is
             # Chassis_Private.nb_cfg_timestamp
             self.assertEqual(updated_at, heartbeat_timestamp)

neutron/tests/unit/plugins/ml2/drivers/ovn/agent/test_neutron_agent.py

@@ -12,6 +12,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import datetime
 from unittest import mock
 
 import eventlet
@@ -67,3 +68,19 @@ class AgentCacheTestCase(base.BaseTestCase):
         agents = list(agents)
         self.assertEqual(1, len(agents))
         self.assertEqual('chassis5', agents[0].agent_id)
+
+    @mock.patch.object(neutron_agent.ControllerAgent, 'alive')
+    def test_heartbeat_timestamp_format(self, agent_alive):
+        chassis_private = fakes.FakeOvsdbRow.create_one_ovsdb_row(
+            attrs={'name': 'chassis5'})
+        agents = self.agent_cache.agents_by_chassis_private(chassis_private)
+        agent = list(agents)[0]
+        agent.chassis.hostname = 'fake-hostname'
+        agent.updated_at = datetime.datetime(
+            year=2023, month=2, day=23, hour=1, minute=2, second=3,
+            microsecond=456789).replace(tzinfo=datetime.timezone.utc)
+        agent_alive.return_value = True
+
+        # Verify that both microseconds and timezone are dropped
+        self.assertEqual(str(agent.as_dict()['heartbeat_timestamp']),
+                         '2023-02-23 01:02:03')

releasenotes/notes/fix-ovn-agent-heartbeat-timestamp-format-dcf80badbe267c68.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Normalise OVN agent heartbeat timestamp format to match other agent types.
+    This fixes parsing of ``GET /v2.0/agents`` for some clients, such as
+    gophercloud.