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Set hot_standby=off only if recovery_target_action=promote (#2570)

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During custom bootstrap the `hot_standby` is set to off to protect postgres from panicking and shutting down when some parameters like `max_connections` are increased on the primary.

According to the [documentation](https://www.postgresql.org/docs/current/runtime-config-wal.html#GUC-RECOVERY-TARGET-ACTION), `hot_standby` set to `off` affects behavior of the `recovery_target_action`, and `pause` starts acting as the `shutdown`:
> If [hot_standby](https://www.postgresql.org/docs/current/runtime-config-replication.html#GUC-HOT-STANDBY) is not enabled, a setting of pause will act the same as shutdown

 This is not what users expect/need, because normally they resolve pause state on their own.

To solve the problem we will set `hot_standby` to `off` during custom bootstrap only if `recovery_target_action` is set to 'promote'.

Close https://github.com/zalando/patroni/issues/2569
This commit is contained in:
Alexander Kukushkin
2023-02-28 10:08:42 +01:00
committed by GitHub
parent 388bb40b71
commit c985974ece
2 changed files with 30 additions and 14 deletions
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patroni/postgresql/config.py
+16 -6
View File
@@ -1094,12 +1094,22 @@ class ConfigHandler(object):
effective_configuration[name] = cvalue
self._postgresql.set_pending_restart(True)
# If we are using custom bootstrap with PITR it could fail when values
# like max_connections are increased, therefore we disable hot_standby.
if self._postgresql.bootstrap.running_custom_bootstrap and \
(self._postgresql.bootstrap.keep_existing_recovery_conf or self._recovery_conf):
effective_configuration['hot_standby'] = 'off'
self._postgresql.set_pending_restart(True)
# If we are using custom bootstrap with PITR it could fail when values like max_connections
# are increased, therefore we disable hot_standby if recovery_target_action == 'promote'.
if self._postgresql.bootstrap.running_custom_bootstrap:
disable_hot_standby = False
if self._postgresql.bootstrap.keep_existing_recovery_conf:
disable_hot_standby = True # trust that pgBackRest does the right thing
# `pause_at_recovery_target` has no effect if hot_standby is not enabled, therefore we consider only 9.5+
elif self._postgresql.major_version >= 90500 and self._recovery_params:
pause_at_recovery_target = parse_bool(self._recovery_params.get('pause_at_recovery_target'))
recovery_target_action = self._recovery_params.get(
'recovery_target_action', 'promote' if pause_at_recovery_target is False else 'pause')
disable_hot_standby = recovery_target_action == 'promote'
if disable_hot_standby:
effective_configuration['hot_standby'] = 'off'
self._postgresql.set_pending_restart(True)
return effective_configuration
tests/test_postgresql.py
+14 -8
View File
@@ -675,14 +675,20 @@ class TestPostgresql(BaseTestPostgresql):
@patch.object(Postgresql, 'get_postgres_role_from_data_directory', Mock(return_value='replica'))
@patch.object(Bootstrap, 'running_custom_bootstrap', PropertyMock(return_value=True))
@patch.object(Bootstrap, 'keep_existing_recovery_conf', PropertyMock(return_value=True))
def test__build_effective_configuration(self):
with patch.object(Postgresql, 'controldata',
Mock(return_value={'max_connections setting': '200',
'max_worker_processes setting': '20',
'max_locks_per_xact setting': '100',
'max_wal_senders setting': 10})):
self.p.cancellable.cancel()
@patch.object(Postgresql, 'controldata', Mock(return_value={'max_connections setting': '200',
'max_worker_processes setting': '20',
'max_locks_per_xact setting': '100',
'max_wal_senders setting': 10}))
@patch('patroni.postgresql.config.logger.warning')
def test_effective_configuration(self, mock_logger):
self.p.cancellable.cancel()
self.p.config.write_recovery_conf({'pause_at_recovery_target': 'false'})
self.assertFalse(self.p.start())
mock_logger.assert_called_once()
self.assertTrue('is missing from pg_controldata output' in mock_logger.call_args[0][0])
self.assertTrue(self.p.pending_restart)
with patch.object(Bootstrap, 'keep_existing_recovery_conf', PropertyMock(return_value=True)):
self.assertFalse(self.p.start())
self.assertTrue(self.p.pending_restart)