[OVN][Placement] Placement init config with Chassis create event

Now the initial Placement configuration per Chassis is build when
a Chassis create event is received. That will happen when:
* The Neutron API is restarted.
* When a new Chassis register is created.

Closes-Bug: #2102090
Change-Id: I9aa8accdcead079fe2e713fe569f8bff7403be92

doc/source/admin/config-qos-min-bw.rst

@@ -325,13 +325,11 @@ by commas.
 This information is retrieved from the OVN SB database during the Neutron
 server initialization and when the "Chassis" registers are updated.
 
-During the Neutron server initialization, a ``MaintenanceWorker`` thread will
-call ``OvnSbSynchronizer.do_sync``, that will call
-``OVNClientPlacementExtension.read_initial_chassis_config``. This method lists
-all chassis and builds the resource provider information needed by Placement.
-This information is stored in the "Chassis" registers, in
-"external_ids:ovn-cms-options", with the same format as retrieved from the
-local "Open_vSwitch" registers from each chassis.
+The initial Placement configuration is retrieved when the Neutron API receives
+a "Chassis" create event, that happens when the IDL is connected to the
+database server. When a creation event is received, the Neutron API reads the
+configuration, builds a ``PlacementState`` instance and sends it to the
+Placement API.
 
 The second method to update the Placement information is when a "Chassis"
 registers is updated. The ``OVNClientPlacementExtension`` extension registers

neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/extensions/placement.py

@@ -125,16 +125,19 @@ class ChassisBandwidthConfigEvent(row_event.RowEvent):
         if self._driver._post_fork_event.is_set():
             return self._driver._ovn_client.placement_extension
 
+    @property
+    def placement_extension_enabled(self):
+        return self.placement_extension and self.placement_extension.enabled
+
     def match_fn(self, event, row, old=None):
-        # If the OVNMechanismDriver OVNClient has not been instantiated, the
-        # event is skipped. All chassis configurations are read during the
-        # OVN placement extension initialization.
-        if (not self.placement_extension or
-                not self.placement_extension.enabled):
-            return False
         if event == self.ROW_CREATE:
             return True
-        if event == self.ROW_UPDATE and old and hasattr(old, 'other_config'):
+
+        # If the OVNMechanismDriver OVNClient has not been instantiated, the
+        # update event is skipped.
+        if not self.placement_extension_enabled:
+            return False
+        if old and hasattr(old, 'other_config'):
             row_bw = _parse_ovn_cms_options(row)
             old_bw = _parse_ovn_cms_options(old)
             if row_bw != old_bw:
@@ -142,6 +145,14 @@ class ChassisBandwidthConfigEvent(row_event.RowEvent):
         return False
 
     def run(self, event, row, old):
+        if event == self.ROW_CREATE:
+            # It is possible that a Chassis create event is received before
+            # the OVNMechanismDriver OVNClient has been instantiated. Wait for
+            # it and check the Placement extension.
+            self._driver._post_fork_event.wait()
+            if not self.placement_extension_enabled:
+                return
+
         name2uuid = self.placement_extension.name2uuid()
         state = self.placement_extension.build_placement_state(row, name2uuid)
         if not state:
@@ -149,7 +160,7 @@ class ChassisBandwidthConfigEvent(row_event.RowEvent):
 
         _send_deferred_batch(state)
         ch_config = dict_chassis_config(state)
-        LOG.debug('OVN chassis %(chassis)s Placement configuration modified: '
+        LOG.info('OVN chassis %(chassis)s Placement configuration modified: '
                  '%(config)s', {'chassis': row.name, 'config': ch_config})
 
 
@@ -228,7 +239,7 @@ class OVNClientPlacementExtension:
         msg = ', '.join(['Chassis {}: {}'.format(
             name, dict_chassis_config(state))
             for (name, state) in chassis.items()]) or '(no info)'
-        LOG.debug('OVN chassis Placement initial configuration: %s', msg)
+        LOG.info('OVN chassis Placement initial configuration: %s', msg)
         return chassis
 
     def name2uuid(self, name=None):

neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_db_sync.py

@@ -1351,9 +1351,6 @@ class OvnSbSynchronizer(OvnDbSynchronizer):
         self.sync_hostname_and_physical_networks(ctx)
         if utils.is_ovn_l3(self.l3_plugin):
             self.l3_plugin.schedule_unhosted_gateways()
-        # NOTE(ralonsoh): this could be called using a resource event.
-        self.ovn_driver._ovn_client.placement_extension.\
-            read_initial_chassis_config()
 
         LOG.debug("OVN-Southbound DB sync process completed @ %s",
                   str(datetime.now()))

neutron/tests/functional/plugins/ml2/drivers/ovn/mech_driver/ovsdb/extensions/test_placement.py

@@ -223,3 +223,34 @@ class TestOVNClientPlacementExtension(base.TestOVNFunctionalBase):
                           common_utils.wait_until_true,
                           lambda: mock_send_placement.called,
                           timeout=2)
+
+    @mock.patch.object(placement_extension, '_send_deferred_batch')
+    def test_chassis_bandwidth_initial_config_event(self, mock_send_placement):
+        ch_name = uuidutils.generate_uuid()
+        rp_uuid = uuidutils.generate_uuid()
+        ch_event = test_ovsdb_monitor.WaitForChassisPrivateCreateEvent(ch_name)
+        self.mech_driver.sb_ovn.idl.notify_handler.watch_event(ch_event)
+        self.mock_name2uuid.return_value = {'host1': rp_uuid}
+        self._create_chassis(
+            'host1', ch_name, physical_nets=['phys1'],
+            bandwidths='br-provider0:1000:2000',
+            inventory_defaults='allocation_ratio:1.0;min_unit:2',
+            hypervisors='br-provider0:host1')
+        self.assertTrue(ch_event.wait())
+        common_utils.wait_until_true(lambda: mock_send_placement.called,
+                                     timeout=2)
+        mock_send_placement.assert_called_once()
+        placement_state = mock_send_placement.call_args[0][0]
+
+        device_mappings = {'phys1': ['br-provider0']}
+        self.assertEqual(placement_state._device_mappings, device_mappings)
+
+        hypervisor_rps = {'br-provider0': {'name': 'host1', 'uuid': rp_uuid}}
+        self.assertEqual(placement_state._hypervisor_rps, hypervisor_rps)
+
+        rp_bandwidths = {'br-provider0': {'egress': 1000, 'ingress': 2000}}
+        self.assertEqual(placement_state._rp_bandwidths, rp_bandwidths)
+
+        rp_inventory_defaults = {'allocation_ratio': 1.0, 'min_unit': 2}
+        self.assertEqual(placement_state._rp_inventory_defaults,
+                         rp_inventory_defaults)

releasenotes/notes/ovn-placement-init-config-6198f572e1dadcba.yaml

@@ -0,0 +1,8 @@
+---
+issues:
+  - |
+    The ML2/OVN Placement initial configuration is executed now in the Neutron
+    API process and removed from the maintenance worker; since the migration
+    to WSGI, now the API and the maintenance worker are different processes.
+    When an OVN ``Chassis`` creation event is received, the configuration is
+    read, a ``PlacementState`` object created and sent to the Placement API.