Files
patroni/tests/__init__.py
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Alexander KukushkinandGitHub c7173aadd7 Failover logical slots (#1820)
Effectively, this PR consists of a few changes:

1. The easy part:
  In case of permanent logical slots are defined in the global configuration, Patroni on the primary will not only create them, but also periodically update DCS with the current values of `confirmed_flush_lsn` for all these slots.
  In order to reduce the number of interactions with DCS the new `/status` key was introduced. It will contain the json object with `optime` and `slots` keys. For backward compatibility the `/optime/leader` will be updated if there are members with old Patroni in the cluster.

2. The tricky part:
  On replicas that are eligible for a failover, Patroni creates the logical replication slot by copying the slot file from the primary and restarting the replica. In order to copy the slot file Patroni opens a connection to the primary with `rewind` or `superuser` credentials and calls `pg_read_binary_file()`  function.
  When the logical slot already exists on the replica Patroni periodically calls `pg_replication_slot_advance()` function, which allows moving the slot forward.

3. Additional requirements:
  In order to ensure that primary doesn't cleanup tuples from pg_catalog that are required for logical decoding, Patroni enables `hot_standby_feedback` on replicas with logical slots and on cascading replicas if they are used for streaming by replicas with logical slots.

4. When logical slots are copied from to the replica there is a timeframe when it could be not safe to use them after promotion. Right now there is no protection from promoting such a replica. But, Patroni will show the warning with names of the slots that might be not safe to use.

Compatibility.
The `pg_replication_slot_advance()` function is only available starting from PostgreSQL 11. For older Postgres versions Patroni will refuse to create the logical slot on the primary.

The old "permanent slots" feature, which creates logical slots right after promotion and before allowing connections, was removed.

Close: https://github.com/zalando/patroni/issues/1749
2021-03-25 16:18:23 +01:00

220 lines
8.9 KiB
Python

import datetime
import os
import shutil
import unittest
from mock import Mock, patch
import psycopg2
import urllib3
from patroni.dcs import Leader, Member
from patroni.postgresql import Postgresql
from patroni.postgresql.config import ConfigHandler
from patroni.utils import RetryFailedError, tzutc
class SleepException(Exception):
pass
class MockResponse(object):
def __init__(self, status_code=200):
self.status_code = status_code
self.content = '{}'
self.reason = 'Not Found'
@property
def data(self):
return self.content.encode('utf-8')
@property
def status(self):
return self.status_code
@staticmethod
def getheader(*args):
return ''
@staticmethod
def getheaders():
return {'content-type': 'json'}
def requests_get(url, **kwargs):
members = '[{"id":14855829450254237642,"peerURLs":["http://localhost:2380","http://localhost:7001"],' +\
'"name":"default","clientURLs":["http://localhost:2379","http://localhost:4001"]}]'
response = MockResponse()
if url.startswith('http://local'):
raise urllib3.exceptions.HTTPError()
elif ':8011/patroni' in url:
response.content = '{"role": "replica", "xlog": {"received_location": 0}, "tags": {}}'
elif url.endswith('/members'):
response.content = '[{}]' if url.startswith('http://error') else members
elif url.startswith('http://exhibitor'):
response.content = '{"servers":["127.0.0.1","127.0.0.2","127.0.0.3"],"port":2181}'
elif url.endswith(':8011/reinitialize'):
data = kwargs.get('data', '')
if ' false}' in data:
response.status_code = 503
response.content = 'restarting after failure already in progress'
else:
response.status_code = 404
return response
class MockPostmaster(object):
def __init__(self, is_running=True, is_single_master=False):
self.is_running = Mock(return_value=is_running)
self.is_single_master = Mock(return_value=is_single_master)
self.wait_for_user_backends_to_close = Mock()
self.signal_stop = Mock(return_value=None)
self.wait = Mock()
self.signal_kill = Mock(return_value=False)
class MockCursor(object):
def __init__(self, connection):
self.connection = connection
self.closed = False
self.rowcount = 0
self.results = []
self.description = [Mock()]
def execute(self, sql, *params):
if sql.startswith('blabla'):
raise psycopg2.ProgrammingError()
elif sql == 'CHECKPOINT' or sql.startswith('SELECT pg_catalog.pg_create_'):
raise psycopg2.OperationalError()
elif sql.startswith('RetryFailedError'):
raise RetryFailedError('retry')
elif sql.startswith('SELECT catalog_xmin'):
self.results = [(100, 501)]
elif sql.startswith('SELECT slot_name, catalog_xmin'):
self.results = [('ls', 100, 500, b'123456')]
elif sql.startswith('SELECT slot_name'):
self.results = [('blabla', 'physical'), ('foobar', 'physical'), ('ls', 'logical', 'a', 'b', 5, 100, 500)]
elif sql.startswith('SELECT CASE WHEN pg_catalog.pg_is_in_recovery()'):
self.results = [(1, 2, 1, 0, False, 1, 1, None, None, [{"slot_name": "ls", "confirmed_flush_lsn": 12345}])]
elif sql.startswith('SELECT pg_catalog.pg_is_in_recovery()'):
self.results = [(False, 2)]
elif sql.startswith('SELECT pg_catalog.pg_postmaster_start_time'):
replication_info = '[{"application_name":"walreceiver","client_addr":"1.2.3.4",' +\
'"state":"streaming","sync_state":"async","sync_priority":0}]'
now = datetime.datetime.now(tzutc)
self.results = [(now, 0, '', 0, '', False, now, replication_info)]
elif sql.startswith('SELECT name, setting'):
self.results = [('wal_segment_size', '2048', '8kB', 'integer', 'internal'),
('wal_block_size', '8192', None, 'integer', 'internal'),
('shared_buffers', '16384', '8kB', 'integer', 'postmaster'),
('wal_buffers', '-1', '8kB', 'integer', 'postmaster'),
('search_path', 'public', None, 'string', 'user'),
('port', '5433', None, 'integer', 'postmaster'),
('listen_addresses', '*', None, 'string', 'postmaster'),
('autovacuum', 'on', None, 'bool', 'sighup'),
('unix_socket_directories', '/tmp', None, 'string', 'postmaster')]
elif sql.startswith('IDENTIFY_SYSTEM'):
self.results = [('1', 3, '0/402EEC0', '')]
elif sql.startswith('TIMELINE_HISTORY '):
self.results = [('', b'x\t0/40159C0\tno recovery target specified\n\n'
b'1\t0/40159C0\tno recovery target specified\n\n'
b'2\t0/402DD98\tno recovery target specified\n\n'
b'3\t0/403DD98\tno recovery target specified\n')]
else:
self.results = [(None, None, None, None, None, None, None, None, None, None)]
def fetchone(self):
return self.results[0]
def fetchall(self):
return self.results
def __iter__(self):
for i in self.results:
yield i
def __enter__(self):
return self
def __exit__(self, *args):
pass
class MockConnect(object):
server_version = 99999
autocommit = False
closed = 0
def cursor(self):
return MockCursor(self)
def __enter__(self):
return self
def __exit__(self, *args):
pass
@staticmethod
def close():
pass
def psycopg2_connect(*args, **kwargs):
return MockConnect()
class PostgresInit(unittest.TestCase):
_PARAMETERS = {'wal_level': 'hot_standby', 'max_replication_slots': 5, 'f.oo': 'bar',
'search_path': 'public', 'hot_standby': 'on', 'max_wal_senders': 5,
'wal_keep_segments': 8, 'wal_log_hints': 'on', 'max_locks_per_transaction': 64,
'max_worker_processes': 8, 'max_connections': 100, 'max_prepared_transactions': 0,
'track_commit_timestamp': 'off', 'unix_socket_directories': '/tmp',
'trigger_file': 'bla', 'stats_temp_directory': '/tmp', 'zero_damaged_pages': '',
'force_parallel_mode': '1', 'constraint_exclusion': '',
'max_stack_depth': 'Z', 'vacuum_cost_limit': -1, 'vacuum_cost_delay': 200}
@patch('psycopg2.connect', psycopg2_connect)
@patch('patroni.postgresql.CallbackExecutor', Mock())
@patch.object(ConfigHandler, 'write_postgresql_conf', Mock())
@patch.object(ConfigHandler, 'replace_pg_hba', Mock())
@patch.object(ConfigHandler, 'replace_pg_ident', Mock())
@patch.object(Postgresql, 'get_postgres_role_from_data_directory', Mock(return_value='master'))
def setUp(self):
data_dir = os.path.join('data', 'test0')
self.p = Postgresql({'name': 'postgresql0', 'scope': 'batman', 'data_dir': data_dir,
'config_dir': data_dir, 'retry_timeout': 10,
'krbsrvname': 'postgres', 'pgpass': os.path.join(data_dir, 'pgpass0'),
'listen': '127.0.0.2, 127.0.0.3:5432', 'connect_address': '127.0.0.2:5432',
'authentication': {'superuser': {'username': 'foo', 'password': 'test'},
'replication': {'username': '', 'password': 'rep-pass'}},
'remove_data_directory_on_rewind_failure': True,
'use_pg_rewind': True, 'pg_ctl_timeout': 'bla',
'parameters': self._PARAMETERS,
'recovery_conf': {'foo': 'bar'},
'pg_hba': ['host all all 0.0.0.0/0 md5'],
'pg_ident': ['krb realm postgres'],
'callbacks': {'on_start': 'true', 'on_stop': 'true', 'on_reload': 'true',
'on_restart': 'true', 'on_role_change': 'true'}})
class BaseTestPostgresql(PostgresInit):
def setUp(self):
super(BaseTestPostgresql, self).setUp()
if not os.path.exists(self.p.data_dir):
os.makedirs(self.p.data_dir)
self.leadermem = Member(0, 'leader', 28, {'conn_url': 'postgres://replicator:[email protected]:5435/postgres'})
self.leader = Leader(-1, 28, self.leadermem)
self.other = Member(0, 'test-1', 28, {'conn_url': 'postgres://replicator:[email protected]:5433/postgres',
'tags': {'replicatefrom': 'leader'}})
self.me = Member(0, 'test0', 28, {'conn_url': 'postgres://replicator:[email protected]:5434/postgres'})
def tearDown(self):
if os.path.exists(self.p.data_dir):
shutil.rmtree(self.p.data_dir)