[ovn] Avoid unwanted ACL_NOT_FOUND error when deleting log objects

There is the possibility that db_remove raises an error if an ACL was
deleted on parallel for other reasons while deleting a log object. On a
normal situation, this command would remove the no-longer-needed
'log-related' property, but since the ACL is no longer there, it will
raise an error. For this case, it is not problematic to have an ACL
deleted mid-operation, so it should not raise any error.

Related-Bug: #2019887

Signed-off-by: Elvira García <egarciar@redhat.com>
Change-Id: I154393529134b5861e0ef0283257ef964fe057fd
(cherry picked from commit e0a2427)

neutron/services/logapi/drivers/ovn/driver.py

@@ -142,7 +142,8 @@ def _remove_acls_log(self, pgs, ovn_txn, log_name=None):
                 if hasattr(acl, 'label'):
                     columns['label'] = 0
                     ovn_txn.add(self.ovn_nb.db_remove(
-                        "ACL", acl_uuid, 'options', 'log-related'))
+                        "ACL", acl_uuid, 'options', 'log-related',
+                        if_exists=True))
                 ovn_txn.add(self.ovn_nb.db_set(
                     "ACL", acl_uuid, *columns.items()))
                 acl_changes += 1

neutron/tests/unit/services/logapi/drivers/ovn/test_driver.py

@@ -27,6 +27,7 @@
 
 FAKE_CFG_RATE = 123
 FAKE_CFG_BURST = 321
+FAKE_LABEL = 1
 
 
 class TestOVNDriverBase(base.BaseTestCase):
@@ -113,6 +114,7 @@ def __init__(self, name=None, **acl_dict):
             acl_defaults_dict = {
                 "name": [name] if name else [],
                 "action": ovn_const.ACL_ACTION_ALLOW_RELATED,
+                "label": FAKE_LABEL
             }
             self.__dict__ = {**acl_defaults_dict, **acl_dict}
 
@@ -247,6 +249,19 @@ def _mock_lookup(_pg_table, acl_uuid, default):
         self.assertEqual(len(pg_dict["acls"]) - 1,
                          self._nb_ovn.db_set.call_count)
 
+    # This test is enforcing the use of if_exists so that we don't get
+    # unexpected errors while doing parallel operations like erasing log
+    # objects and security groups
+    @mock.patch.object(ovn_driver.LOG, 'info')
+    def test__remove_acls_log_only_if_exists(self, m_info):
+        pg_dict = self._fake_pg_dict(acls=['acl1', 'acl2', 'acl3'])
+
+        def _only_if_exists(_pg_table, acl_uuid, col, val, if_exists):
+            self.assertTrue(if_exists)
+
+        self._nb_ovn.db_remove.side_effect = _only_if_exists
+        self._log_driver._remove_acls_log([pg_dict], self._nb_ovn.transaction)
+
     @mock.patch.object(ovn_driver.LOG, 'info')
     def test__remove_acls_log_with_log_name(self, m_info):
         pg_dict = self._fake_pg_dict(acls=['acl1', 'acl2', 'acl3', 'acl4'])