Script to remove duplicated port bindings

A new script to remove the duplicated port bindings was added. This
script will list all ``ml2_port_bindings`` records in the database,
finding those ones with the same port ID. Then the script removes
those ones with status=INACTIVE. This script is useful to remove
those leftovers that remain in the database after a failed live
migration.

"dry_run" mode is possible if selected in "[cli_script] dry_run"
boolean config option. The duplicated port bindings are printed in
the shell but not deleted.

Related-Bug: #1979072

Change-Id: I0de5fbb70eb852f82bd311616557985d1ce89bbf

doc/source/contributor/internals/live_migration.rst

@@ -172,6 +172,27 @@ after migration finished. During this time window, the instance might not be
 reachable via the network. This should be solved with bug
 https://bugs.launchpad.net/nova/+bug/1605016
 
+Error recovery
+--------------
+
+If the Live Migration fails, Nova will revert the operation. That implies
+deleting any object created in the database or in the destination compute
+node. However, in some cases have been reported the presence of `duplicated
+port bindings per port <https://bugs.launchpad.net/neutron/+bug/1979072>`_.
+In this state, the port cannot be migrated until the inactive port binding
+(the failed destination host port binding) has been deleted.
+
+To this end, the script ``neutron-remove-duplicated-port-bindings`` has been
+created. This script finds all duplicated port binding (that means, all port
+bindings that point to the same port) and deletes the inactive one.
+
+.. note::
+
+   This script cannot be executed while a Live Migration or a cross cell Cold
+   Migration. The script will delete the inactive port binding and will break
+   the process.
+
+
 Flow Diagram
 ------------
 

neutron/cmd/remove_duplicated_port_bindings.py

@@ -0,0 +1,71 @@
+# Copyright (c) 2022 Red Hat, Inc.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from neutron_lib import constants
+from neutron_lib import context
+from neutron_lib.db import api as db_api
+from oslo_config import cfg
+from oslo_db import options as db_options
+from oslo_log import log as logging
+
+from neutron.common import config as common_config
+from neutron.objects import ports as ports_obj
+
+
+LOG = logging.getLogger(__name__)
+
+
+def setup_conf(conf):
+    common_config.register_common_config_options()
+    db_group, neutron_db_opts = db_options.list_opts()[0]
+    conf.register_cli_opts(neutron_db_opts, db_group)
+    conf()
+
+
+def main():
+    """Main method for removing the duplicated port binding registers.
+
+    This script finds all ``PortBinding`` registers with the same ``port_id``.
+    That happens during the live-migration process. Once finished, the inactive
+    port binding register is deleted. However, it could happen that during the
+    live-migration, an error occurs and this deletion is not executed. The
+    related port cannot be migrated anymore.
+
+    This script should not be executed during a live migration process. It will
+    remove the inactive port binding and will break the migration.
+    """
+    conf = cfg.CONF
+    setup_conf(conf)
+    _dry_run = conf.cli_script.dry_run
+    admin_ctx = context.get_admin_context()
+    with db_api.CONTEXT_WRITER.using(admin_ctx):
+        dup_pbindings = ports_obj.PortBinding.get_duplicated_port_bindings(
+            admin_ctx)
+
+        # Clean duplicated port bindings that are INACTIVE (if not in dry-run).
+        if not _dry_run:
+            for pbinding in dup_pbindings:
+                ports_obj.PortBinding.delete_objects(
+                    admin_ctx, status=constants.INACTIVE,
+                    port_id=pbinding.port_id)
+
+        if dup_pbindings:
+            port_ids = [pbinding.port_id for pbinding in dup_pbindings]
+            action = 'can be' if _dry_run else 'have been'
+            LOG.info('The following duplicated PortBinding registers with '
+                     'status=INACTIVE %s removed, port_ids: %s',
+                     action, port_ids)
+        else:
+            LOG.info('No duplicated PortBinding registers has been found.')

neutron/common/config.py

@@ -87,6 +87,9 @@ def register_common_config_options():
                                              common_config.IRONIC_CONF_SECTION)
     common_config.register_ironic_opts()
 
+    # Register the CLI script configuration options.
+    common_config.register_cli_script_opts()
+
     _COMMON_OPTIONS_ALREADY_REGISTERED = True
 
 

neutron/conf/common.py

@@ -216,3 +216,16 @@ ironic_opts = [
 
 def register_ironic_opts(cfg=cfg.CONF):
     cfg.register_opts(ironic_opts, group=IRONIC_CONF_SECTION)
+
+
+CLI_SCRIPT_SECTION = 'cli_script'
+
+cli_script_options = [
+    cfg.BoolOpt('dry_run', default=False,
+                help=_('Dry-run execution of the CLI script. No change will '
+                       'be performed on the system.')),
+]
+
+
+def register_cli_script_opts(cfg=cfg.CONF):
+    cfg.register_opts(cli_script_options, group=CLI_SCRIPT_SECTION)

neutron/objects/ports.py

@@ -20,6 +20,7 @@ from neutron_lib.utils import net as net_utils
 from oslo_log import log as logging
 from oslo_utils import versionutils
 from oslo_versionedobjects import fields as obj_fields
+import sqlalchemy
 from sqlalchemy import and_
 
 from neutron.common import _constants
@@ -102,6 +103,13 @@ class PortBinding(PortBindingBase):
                 cls.db_model.status == status))
             return query.all()
 
+    @classmethod
+    @db_api.CONTEXT_READER
+    def get_duplicated_port_bindings(cls, context):
+        return context.session.query(
+            cls.db_model).group_by(
+            cls.db_model.port_id).having(sqlalchemy.func.count() > 1).all()
+
 
 @base.NeutronObjectRegistry.register
 class DistributedPortBinding(PortBindingBase):

neutron/tests/unit/objects/test_ports.py

@@ -54,6 +54,17 @@ class PortBindingDbObjectTestCase(obj_test_base.BaseDbObjectTestCase,
                                   BasePortBindingDbObjectTestCase):
     _test_class = ports.PortBinding
 
+    def test_get_duplicated_port_bindings(self):
+        port_id = self._create_test_port_id()
+        self.update_obj_fields({'port_id': port_id},
+                               objs=[self.objs[0], self.objs[1]])
+        for i in range(3):
+            _obj = self._make_object(self.obj_fields[i])
+            _obj.create()
+        dup_pb = ports.PortBinding.get_duplicated_port_bindings(self.context)
+        self.assertEqual(1, len(dup_pb))
+        self.assertEqual(port_id, dup_pb[0].port_id)
+
 
 class DistributedPortBindingIfaceObjTestCase(
         obj_test_base.BaseObjectIfaceTestCase):

releasenotes/notes/remove-duplicated-port-bindings-83b58060f3adb403.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    A new script to remove the duplicated port bindings was added. This script
+    will list all ``ml2_port_bindings`` records in the database, finding those
+    ones with the same port ID. Then the script removes those ones with
+    status=INACTIVE. This script is useful to remove those leftovers that
+    remain in the database after a failed live migration. It is important to
+    remark that this script should not be executed during any live migration
+    process.

setup.cfg

@@ -62,6 +62,7 @@ console_scripts =
     neutron-ovn-db-sync-util = neutron.cmd.ovn.neutron_ovn_db_sync_util:main
     neutron-sanitize-port-binding-profile-allocation = neutron.cmd.sanitize_port_binding_profile_allocation:main
     neutron-sanitize-port-mac-addresses = neutron.cmd.sanitize_port_mac_addresses:main
+    neutron-remove-duplicated-port-bindings = neutron.cmd.remove_duplicated_port_bindings:main
     ml2ovn-trace = neutron.cmd.ovn.ml2ovn_trace:main
 neutron.core_plugins =
     ml2 = neutron.plugins.ml2.plugin:Ml2Plugin