Get rid of pkg_resources

... because it was removed in Python 3.12 [1].

[1] https://docs.python.org/3/whatsnew/3.12.html#ensurepip

Note:
Selectable entry points were introduced in importlib_metadata 3.6 and
Python 3.10 .

Change-Id: I1b478a63ad1d73f9f3528939362797ea1fc68534

neutron/conf/db/migration_cli.py

@@ -10,16 +10,21 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import sys
+
 from oslo_config import cfg
-import pkg_resources
 
 from neutron._i18n import _
 
+if sys.version_info < (3, 10, 0):
+    from importlib_metadata import entry_points
+else:
+    from importlib.metadata import entry_points
 
 MIGRATION_ENTRYPOINTS = 'neutron.db.alembic_migrations'
 migration_entrypoints = {
     entrypoint.name: entrypoint
-    for entrypoint in pkg_resources.iter_entry_points(MIGRATION_ENTRYPOINTS)
+    for entrypoint in entry_points(group=MIGRATION_ENTRYPOINTS)
 }
 
 INSTALLED_SUBPROJECTS = list(migration_entrypoints)

neutron/db/migration/cli.py

@@ -566,13 +566,13 @@ def _get_installed_entrypoint(subproject):
 def _get_subproject_script_location(subproject):
     '''Get the script location for the installed subproject.'''
     entrypoint = _get_installed_entrypoint(subproject)
-    return ':'.join([entrypoint.module_name, entrypoint.attrs[0]])
+    return ':'.join([entrypoint.module, entrypoint.attr])
 
 
 def _get_subproject_base(subproject):
     '''Get the import base name for the installed subproject.'''
     entrypoint = _get_installed_entrypoint(subproject)
-    return entrypoint.module_name.split('.')[0]
+    return entrypoint.module.split('.')[0]
 
 
 def get_alembic_version_table(config):

neutron/tests/unit/db/test_migration.py

@@ -14,6 +14,7 @@
 #    under the License.
 
 import copy
+import importlib.metadata
 import os
 import re
 import sys
@@ -28,7 +29,6 @@ import fixtures
 from neutron_lib import fixture as lib_fixtures
 from neutron_lib.utils import helpers
 from oslo_utils import fileutils
-import pkg_resources
 import sqlalchemy as sa
 from testtools import matchers
 
@@ -143,13 +143,13 @@ class TestCli(base.BaseTestCase):
             config = alembic_config.Config(ini)
             config.set_main_option('neutron_project', project)
             module_name = project.replace('-', '_') + '.db.migration'
-            attrs = ('alembic_migrations',)
-            script_location = ':'.join([module_name, attrs[0]])
+            script_location = ':'.join([module_name, 'alembic_migrations'])
             config.set_main_option('script_location', script_location)
             self.configs.append(config)
-            entrypoint = pkg_resources.EntryPoint(project,
-                                                  module_name,
-                                                  attrs=attrs)
+            entrypoint = importlib.metadata.EntryPoint(
+                name=project,
+                group='neutron.db.alembic_migrations',
+                value=script_location)
             migration_cli.migration_entrypoints[project] = entrypoint
 
     def _main_test_helper(self, argv, func_name, exp_kwargs=[{}]):

requirements.txt

@@ -56,3 +56,6 @@ python-designateclient>=2.7.0 # Apache-2.0
 os-vif>=3.1.0 # Apache-2.0
 futurist>=1.2.0 # Apache-2.0
 tooz>=1.58.0 # Apache-2.0
+
+# TODO(tkajinam): Remove importlib_metadata when python 3.9 support is dropped
+importlib_metadata>=3.6;python_version<"3.10" # Apache-2.0