Files
patroni/tests/__init__.py
T
Alexander KukushkinandGitHub 4872ac51e0 Citus integration (#2504)
Citus cluster (coordinator and workers) will be stored in DCS as a fleet of Patroni logically grouped together:
```
/service/batman/
/service/batman/0/
/service/batman/0/initialize
/service/batman/0/leader
/service/batman/0/members/
/service/batman/0/members/m1
/service/batman/0/members/m2
/service/batman/
/service/batman/1/
/service/batman/1/initialize
/service/batman/1/leader
/service/batman/1/members/
/service/batman/1/members/m1
/service/batman/1/members/m2
...
```

Where 0 is a Citus group for coordinator and 1, 2, etc are worker groups.

Such hierarchy allows reading the entire Citus cluster with a single call to DCS (except Zookeeper).

The get_cluster() method will be reading the entire Citus cluster on the coordinator because it needs to discover workers. For the worker cluster it will be reading the subtree of its own group.

Besides that we introduce a new method  get_citus_coordinator(). It will be used only by worker clusters.

Since there is no hierarchical structures on K8s we will use the citus group suffix on all objects that Patroni creates.
E.g.
```
batman-0-leader  # the leader config map for the coordinator
batman-0-config  # the config map holding initialize, config, and history "keys"
...
batman-1-leader  # the leader config map for worker group 1
batman-1-config
...
```

Citus integration is enabled from patroni.yaml:
```yaml
citus:
  database: citus
  group: 0  # 0 is for coordinator, 1, 2, etc are for workers
```

If enabled, Patroni will create the database, citus extension in it, and INSERTs INTO `pg_dist_authinfo` information required for Citus nodes to communicate between each other, i.e. 'password', 'sslcert', 'sslkey' for superuser if they are defined in the Patroni configuration file.

When the new Citus coordinator/worker is bootstrapped, Patroni adds `synchronous_mode: on` to the `bootstrap.dcs` section.

Besides that, Patroni takes over management of some Postgres GUCs:
- `shared_preload_libraries` - Patroni ensures that the "citus" is added to the first place
- `max_prepared_transactions` - if not set or set to 0, Patroni changes the value to `max_connections*2`
- wal_level - automatically set to logical. It is used by Citus to move/split shards. Under the hood Citus is creating/removing replication slots and they are automatically added by Patroni to the `ignore_slots` configuration to avoid accidental removal.

The coordinator primary actively discovers worker primary nodes and registers/updates them in the `pg_dist_node` table using
citus_add_node() and citus_update_node() functions.

Patroni running on the coordinator provides the new REST API endpoint: `POST /citus`. It is used by workers to facilitate controlled switchovers and restarts of worker primaries.
When the worker primary needs to shut down Postgres because of restart or switchover, it calls the `POST /citus` endpoint on the coordinator and the Patroni on the coordinator starts a transaction and calls `citus_update_node(nodeid, 'host-demoted', port)` in order to pause client connections that work with the given worker.
Once the new leader is elected or postgres started back, they perform another call to the `POST/citus` endpoint, that does another `citus_update_node()` call with actual hostname and port and commits a transaction. After transaction is committed, coordinator reestablishes connections to the worker node and client connections are unblocked.
If clients don't run long transaction the operation finishes without client visible errors, but only a short latency spike.

All operations on the `pg_dist_node` are serialized by Patroni on the coordinator. It allows to have more control and ROLLBACK transaction in progress if its lifetime exceeding a certain threshold and there are other worker nodes should be updated.
2023-01-24 16:14:58 +01:00

235 lines
9.9 KiB
Python

import datetime
import os
import shutil
import unittest
from mock import Mock, patch
import urllib3
import patroni.psycopg as psycopg
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, method='GET', endpoint=None, data='', **kwargs):
members = '[{"id":14855829450254237642,"peerURLs":["http://localhost:2380","http://localhost:7001"],' +\
'"name":"default","clientURLs":["http://localhost:2379","http://localhost:4001"]}]'
response = MockResponse()
if endpoint == 'failsafe':
response.content = 'Accepted'
elif url.startswith('http://local'):
raise urllib3.exceptions.HTTPError()
elif ':8011/patroni' in url:
response.content = '{"role": "replica", "wal": {"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'):
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 psycopg.ProgrammingError()
elif sql == 'CHECKPOINT' or sql.startswith('SELECT pg_catalog.pg_create_'):
raise psycopg.OperationalError()
elif sql.startswith('RetryFailedError'):
raise RetryFailedError('retry')
elif sql.startswith('SELECT slot_name, catalog_xmin'):
self.results = [('postgresql0', 100), ('ls', 100)]
elif sql.startswith('SELECT slot_name, slot_type, datname, plugin, catalog_xmin'):
self.results = [('ls', 'logical', 'a', 'b', 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('WITH slots AS (SELECT slot_name, active'):
self.results = [(False, True)]
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}],
'on', 'n1', None)]
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')]
elif sql.startswith('SELECT pg_catalog.citus_add_node'):
self.results = [(2,)]
elif sql.startswith('SELECT nodeid, groupid'):
self.results = [(1, 0, 'host1', 5432, 'primary'), (2, 1, 'host2', 5432, 'primary')]
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 psycopg_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('patroni.psycopg._connect', psycopg_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', 'proxy_address': '127.0.0.2:5433',
'authentication': {'superuser': {'username': 'foo', 'password': 'test'},
'replication': {'username': '', 'password': 'rep-pass'},
'rewind': {'username': 'rewind', 'password': 'test'}},
'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'},
'citus': {'group': 0, 'database': 'citus'}})
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, {
'state': 'running', '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',
'state': 'running', 'tags': {'replicatefrom': 'leader'}})
self.me = Member(0, 'test0', 28, {
'state': 'running', '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)