Handle exception from iterdir while discovering static files (patroni#3152)

Close patroni#3151

Author: CyberDem0n

patroni/postgresql/available_parameters/__init__.py

@@ -42,7 +42,10 @@ def _traversable_walk(tvbs: Iterator[PathLikeObj]) -> Iterator[PathLikeObj]:
         if tvb.is_file():
             yield tvb
         elif tvb.is_dir():
-            yield from _traversable_walk(tvb.iterdir())
+            try:
+                yield from _traversable_walk(tvb.iterdir())
+            except Exception as e:
+                logger.debug("Can't list directory %s: %r", tvb, e)
 
 
 def _filter_and_sort_files(files: Iterator[PathLikeObj]) -> Iterator[PathLikeObj]:

tests/test_postgresql.py

@@ -1112,7 +1112,8 @@ def test__load_postgres_gucs_validators(self):
         file1_attrs = {'is_file.return_value': True, 'is_dir.return_value': False}
         file1_mock = MagicMock(**file1_attrs)
         file1_mock.name = '__init__.py'
-        file2_attrs = {'is_file.return_value': False, 'is_dir.return_value': True, 'iterdir.return_value': []}
+        file2_attrs = {'is_file.return_value': False, 'is_dir.return_value': True,
+                       'iterdir.side_effect':  PermissionError(13, 'Permission denied')}
         file2_mock = MagicMock(**file2_attrs)
         file2_mock.name = '__pycache__'
         file3_attrs = {'is_file.return_value': True, 'is_dir.return_value': False}
@@ -1126,9 +1127,11 @@ def test__load_postgres_gucs_validators(self):
         dir_mock = MagicMock(**dir_attrs)
         dir_mock.iterdir.return_value = [file1_mock, file2_mock, file3_mock, file4_mock]
         with patch('patroni.postgresql.available_parameters.conf_dir', dir_mock), \
+             patch('patroni.postgresql.available_parameters.logger.debug') as mock_debug, \
              patch('patroni.postgresql.available_parameters.logger.info') as mock_info, \
              patch('patroni.postgresql.validator.logger.warning') as mock_warning:
             _load_postgres_gucs_validators()
+            self.assertEqual(mock_debug.call_args[0][0], "Can't list directory %s: %r")
             mock_info.assert_called_once_with('Ignored a non-YAML file found under `%s` '
                                               'directory: `%s`.', 'available_parameters', file4_mock)
             mock_warning.assert_called_once()