[OVN] Update ovn meter when neutron server reloads

Up until now, we needed to remove all logging objects to see the
meter-band properties being changed after a server restart. Now we check
for inconsistencies between the neutron configuration and the OVN
meter-band object after a restart. The function create_ovn_fair_meter is
now located in the ovn_driver instead of the log_driver so as to be able
to call it from the maintenance task.

Closes-bug: #2017145
Signed-off-by: Elvira García <egarciar@redhat.com>
Change-Id: I24cef85ed68c893a740445707f88296d763c8de8

2 files changed, 71 insertions, 0 deletions

diff --git a/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/maintenance.py b/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/maintenance.py
index 0f3deed9a1..7f4b15c0ee 100644
--- a/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/maintenance.py
+++ b/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/maintenance.py
@@ -41,6 +41,7 @@ from neutron.db import ovn_revision_numbers_db as revision_numbers_db
 from neutron.objects import ports as ports_obj
 from neutron.objects import router as router_obj
 from neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb import ovn_db_sync
+from neutron.services.logapi.drivers.ovn import driver as log_driver
 
 
 CONF = cfg.CONF
@@ -1016,6 +1017,24 @@ class DBInconsistenciesPeriodics(SchemaAwarePeriodicsBase):
 
         raise periodics.NeverAgain()
 
+    @periodics.periodic(spacing=600, run_immediately=True)
+    def check_fair_meter_consistency(self):
+        """Update the logging meter after neutron-server reload
+
+        When we change the rate and burst limit we need to update the fair
+        meter band to apply the new values. This is called from the ML2/OVN
+        driver after the OVN NB idl is loaded
+
+        """
+        if not self.has_lock:
+            return
+        if log_driver.OVNDriver.network_logging_supported(self._nb_idl):
+            meter_name = (
+                cfg.CONF.network_log.local_output_log_base or "acl_log_meter")
+            self._ovn_client.create_ovn_fair_meter(meter_name,
+                                                   from_reload=True)
+        raise periodics.NeverAgain()
+
 
 class HashRingHealthCheckPeriodics(object):
 
diff --git a/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py b/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py
index 11650493ef..9a40a568f2 100644
--- a/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py
+++ b/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py
@@ -31,6 +31,7 @@ from neutron_lib.exceptions import l3 as l3_exc
 from neutron_lib.plugins import constants as plugin_constants
 from neutron_lib.plugins import directory
 from neutron_lib.plugins import utils as p_utils
+from neutron_lib.services.logapi import constants as log_const
 from neutron_lib.utils import helpers
 from neutron_lib.utils import net as n_net
 from oslo_config import cfg
@@ -2647,3 +2648,54 @@ class OVNClient(object):
             if ls_dns_record.records.get(ptr_record):
                 txn.add(self._nb_idl.dns_remove_record(
                     ls_dns_record.uuid, ptr_record, if_exists=True))
+
+    def create_ovn_fair_meter(self, meter_name, from_reload=False, txn=None):
+        """Create row in Meter table with fair attribute set to True.
+
+        Create a row in OVN's NB Meter table based on well-known name. This
+        method uses the network_log configuration to specify the attributes
+        of the meter. Current implementation needs only one 'fair' meter row
+        which is then referred by multiple ACL rows.
+
+        :param meter_name: ovn northbound meter name.
+        :param from_reload: whether we update the meter values or create them.
+        :txn: ovn northbound idl transaction.
+
+        """
+        meter = self._nb_idl.db_find_rows(
+            "Meter", ("name", "=", meter_name)).execute(check_error=True)
+        # The meter is created when a log object is created, not by default.
+        # This condition avoids creating the meter if it wasn't there already
+        commands = []
+        if from_reload and not meter:
+            return
+        if meter:
+            meter = meter[0]
+            meter_band = self._nb_idl.lookup("Meter_Band",
+                                             meter.bands[0].uuid, default=None)
+            if meter_band:
+                if all((meter.unit == "pktps",
+                        meter.fair[0],
+                        meter_band.rate == cfg.CONF.network_log.rate_limit,
+                        meter_band.burst_size ==
+                        cfg.CONF.network_log.burst_limit)):
+                    # Meter (and its meter-band) unchanged: noop.
+                    return
+            # Re-create meter (and its meter-band) with the new attributes.
+            # This is supposed to happen only if configuration changed, so
+            # doing updates is an overkill: better to leverage the ovsdbapp
+            # library to avoid the complexity.
+            LOG.info("Deleting outdated log fair meter %s", meter_name)
+            commands.append(self._nb_idl.meter_del(meter.uuid))
+        # Create meter
+        LOG.info("Creating network log fair meter %s", meter_name)
+        commands.append(self._nb_idl.meter_add(
+                        name=meter_name,
+                        unit="pktps",
+                        rate=cfg.CONF.network_log.rate_limit,
+                        fair=True,
+                        burst_size=cfg.CONF.network_log.burst_limit,
+                        may_exist=False,
+                        external_ids={ovn_const.OVN_DEVICE_OWNER_EXT_ID_KEY:
+                                      log_const.LOGGING_PLUGIN}))
+        self._transaction(commands, txn=txn)