Files
patroni/tests/test_etcd.py
T
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

322 lines
15 KiB
Python

import etcd
import urllib3.util.connection
import socket
import unittest
from dns.exception import DNSException
from mock import Mock, patch
from patroni.dcs.etcd import AbstractDCS, EtcdClient, Cluster, Etcd, EtcdError, DnsCachingResolver
from patroni.exceptions import DCSError
from patroni.utils import Retry
from urllib3.exceptions import ReadTimeoutError
from . import SleepException, MockResponse, requests_get
def etcd_watch(self, key, index=None, timeout=None, recursive=None):
if timeout == 2.0:
raise etcd.EtcdWatchTimedOut
elif timeout == 5.0:
return etcd.EtcdResult('compareAndSwap', {})
elif 5 < timeout <= 10.0:
raise etcd.EtcdException
elif timeout == 20.0:
raise etcd.EtcdEventIndexCleared
def etcd_write(self, key, value, **kwargs):
if key == '/service/exists/leader':
raise etcd.EtcdAlreadyExist
if key in ['/service/test/leader', '/patroni/test/leader'] and \
(kwargs.get('prevValue') == 'foo' or not kwargs.get('prevExist', True)):
return True
raise etcd.EtcdException
def etcd_read(self, key, **kwargs):
if key == '/service/noleader/':
raise DCSError('noleader')
elif key == '/service/nocluster/':
raise etcd.EtcdKeyNotFound
response = {"action": "get", "node": {"key": "/service/batman5", "dir": True, "nodes": [
{"key": "/service/batman5/config", "value": '{"synchronous_mode": 0}',
"modifiedIndex": 1582, "createdIndex": 1582},
{"key": "/service/batman5/failover", "value": "",
"modifiedIndex": 1582, "createdIndex": 1582},
{"key": "/service/batman5/initialize", "value": "postgresql0",
"modifiedIndex": 1582, "createdIndex": 1582},
{"key": "/service/batman5/leader", "value": "postgresql1",
"expiration": "2015-05-15T09:11:00.037397538Z", "ttl": 21,
"modifiedIndex": 20728, "createdIndex": 20434},
{"key": "/service/batman5/optime", "dir": True, "nodes": [
{"key": "/service/batman5/optime/leader", "value": "2164261704",
"modifiedIndex": 20729, "createdIndex": 20729}],
"modifiedIndex": 20437, "createdIndex": 20437},
{"key": "/service/batman5/sync", "value": '{"leader": "leader"}',
"modifiedIndex": 1582, "createdIndex": 1582},
{"key": "/service/batman5/members", "dir": True, "nodes": [
{"key": "/service/batman5/members/postgresql1",
"value": "postgres://replicator:[email protected]:5434/postgres" +
"?application_name=http://127.0.0.1:8009/patroni",
"expiration": "2015-05-15T09:10:59.949384522Z", "ttl": 21,
"modifiedIndex": 20727, "createdIndex": 20727},
{"key": "/service/batman5/members/postgresql0",
"value": "postgres://replicator:[email protected]:5433/postgres" +
"?application_name=http://127.0.0.1:8008/patroni",
"expiration": "2015-05-15T09:11:09.611860899Z", "ttl": 30,
"modifiedIndex": 20730, "createdIndex": 20730}],
"modifiedIndex": 1581, "createdIndex": 1581},
{"key": "/service/batman5/status", "value": '{"optime":2164261704,"slots":{"ls":12345}}',
"modifiedIndex": 1582, "createdIndex": 1582}], "modifiedIndex": 1581, "createdIndex": 1581}}
if key == '/service/legacy/':
response['node']['nodes'].pop()
if key == '/service/broken/':
response['node']['nodes'][-1]['value'] = '{'
result = etcd.EtcdResult(**response)
result.etcd_index = 0
return result
def dns_query(name, _):
if '-server' not in name or '-ssl' in name:
return []
if name == '_etcd-server._tcp.blabla':
return []
elif name == '_etcd-server._tcp.exception':
raise DNSException()
srv = Mock()
srv.port = 2380
srv.target.to_text.return_value = 'localhost' if name == '_etcd-server._tcp.foobar' else '127.0.0.1'
return [srv]
def socket_getaddrinfo(*args):
if args[0] in ('ok', 'localhost', '127.0.0.1'):
return [(socket.AF_INET, 1, 6, '', ('127.0.0.1', 0)), (socket.AF_INET6, 1, 6, '', ('::1', 0))]
raise socket.gaierror
def http_request(method, url, **kwargs):
if url == 'http://localhost:2379/timeout':
raise ReadTimeoutError(None, None, None)
ret = MockResponse()
if url == 'http://localhost:2379/v2/machines':
ret.content = 'http://localhost:2379,http://localhost:4001'
elif url == 'http://localhost:4001/v2/machines':
ret.content = ''
elif url != 'http://localhost:2379/':
raise socket.error
return ret
class TestDnsCachingResolver(unittest.TestCase):
@patch('time.sleep', Mock(side_effect=SleepException))
@patch('socket.getaddrinfo', Mock(side_effect=socket.gaierror))
def test_run(self):
r = DnsCachingResolver()
r._invoke_excepthook = Mock()
self.assertIsNone(r.resolve_async('', 0))
r.join()
@patch('dns.resolver.query', dns_query)
@patch('socket.getaddrinfo', socket_getaddrinfo)
@patch('patroni.dcs.etcd.requests_get', requests_get)
class TestClient(unittest.TestCase):
@patch('dns.resolver.query', dns_query)
@patch('socket.getaddrinfo', socket_getaddrinfo)
@patch('patroni.dcs.etcd.requests_get', requests_get)
def setUp(self):
with patch.object(EtcdClient, 'machines') as mock_machines:
mock_machines.__get__ = Mock(return_value=['http://localhost:2379', 'http://localhost:4001'])
self.client = EtcdClient({'srv': 'test', 'retry_timeout': 3}, DnsCachingResolver())
self.client.http.request = http_request
self.client.http.request_encode_body = http_request
def test_machines(self):
self.client._base_uri = 'http://localhost:4002'
self.client._machines_cache = ['http://localhost:4002', 'http://localhost:2379']
self.assertIsNotNone(self.client.machines)
self.client._base_uri = 'http://localhost:4001'
self.client._machines_cache = ['http://localhost:4001']
self.client._update_machines_cache = True
machines = None
try:
machines = self.client.machines
self.assertFail()
except Exception:
self.assertIsNone(machines)
@patch.object(EtcdClient, 'machines')
def test_api_execute(self, mock_machines):
mock_machines.__get__ = Mock(return_value=['http://localhost:4001', 'http://localhost:2379'])
self.client._base_uri = 'http://localhost:4001'
self.assertRaises(etcd.EtcdException, self.client.api_execute, '/', 'POST', timeout=0)
self.client._base_uri = 'http://localhost:4001'
rtry = Retry(deadline=10, max_delay=1, max_tries=-1, retry_exceptions=(etcd.EtcdLeaderElectionInProgress,))
rtry(self.client.api_execute, '/', 'POST', timeout=0, params={'retry': rtry})
self.client._machines_cache_updated = 0
self.client.api_execute('/', 'POST', timeout=0)
self.client._machines_cache = [self.client._base_uri]
self.assertRaises(etcd.EtcdWatchTimedOut, self.client.api_execute, '/timeout', 'POST', params={'wait': 'true'})
self.assertRaises(etcd.EtcdWatchTimedOut, self.client.api_execute, '/timeout', 'POST', params={'wait': 'true'})
with patch.object(EtcdClient, '_calculate_timeouts', Mock(side_effect=[(1, 1, 0), (1, 1, 0), (0, 1, 0)])),\
patch.object(EtcdClient, '_load_machines_cache', Mock(side_effect=Exception)):
self.client.http.request = Mock(side_effect=socket.error)
self.assertRaises(etcd.EtcdException, rtry, self.client.api_execute, '/', 'GET', params={'retry': rtry})
with patch.object(EtcdClient, '_calculate_timeouts', Mock(side_effect=[(1, 1, 0), (1, 1, 0), (0, 1, 0)])),\
patch.object(EtcdClient, '_load_machines_cache', Mock(return_value=True)):
self.assertRaises(etcd.EtcdException, rtry, self.client.api_execute, '/', 'GET', params={'retry': rtry})
with patch.object(EtcdClient, '_do_http_request', Mock(side_effect=etcd.EtcdException)):
self.client._read_timeout = 0.01
self.assertRaises(etcd.EtcdException, self.client.api_execute, '/', 'GET')
def test_get_srv_record(self):
self.assertEqual(self.client.get_srv_record('_etcd-server._tcp.blabla'), [])
self.assertEqual(self.client.get_srv_record('_etcd-server._tcp.exception'), [])
def test__get_machines_cache_from_srv(self):
self.client._get_machines_cache_from_srv('foobar')
self.client.get_srv_record = Mock(return_value=[('localhost', 2380)])
self.client._get_machines_cache_from_srv('blabla')
def test__get_machines_cache_from_dns(self):
self.client._get_machines_cache_from_dns('error', 2379)
@patch.object(EtcdClient, 'machines')
def test__refresh_machines_cache(self, mock_machines):
mock_machines.__get__ = Mock(side_effect=etcd.EtcdConnectionFailed)
self.assertIsNone(self.client._refresh_machines_cache())
self.assertRaises(etcd.EtcdException, self.client._refresh_machines_cache, True)
def test__load_machines_cache(self):
self.client._config = {}
self.assertRaises(Exception, self.client._load_machines_cache)
self.client._config = {'srv': 'blabla'}
self.assertRaises(etcd.EtcdException, self.client._load_machines_cache)
@patch.object(socket.socket, 'connect')
def test_create_connection_patched(self, mock_connect):
self.assertRaises(socket.error, urllib3.util.connection.create_connection, ('fail', 2379))
urllib3.util.connection.create_connection(('[localhost]', 2379))
mock_connect.side_effect = socket.error
self.assertRaises(socket.error, urllib3.util.connection.create_connection, ('[localhost]', 2379),
timeout=1, source_address=('localhost', 53333),
socket_options=[(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)])
def test___del__(self):
self.client.http.clear = Mock(side_effect=TypeError)
del self.client
@patch('patroni.dcs.etcd.requests_get', requests_get)
@patch('socket.getaddrinfo', socket_getaddrinfo)
@patch.object(etcd.Client, 'write', etcd_write)
@patch.object(etcd.Client, 'read', etcd_read)
@patch.object(etcd.Client, 'delete', Mock(side_effect=etcd.EtcdException))
class TestEtcd(unittest.TestCase):
@patch('socket.getaddrinfo', socket_getaddrinfo)
def setUp(self):
with patch.object(EtcdClient, 'machines') as mock_machines:
mock_machines.__get__ = Mock(return_value=['http://localhost:2379', 'http://localhost:4001'])
self.etcd = Etcd({'namespace': '/patroni/', 'ttl': 30, 'retry_timeout': 10,
'host': 'localhost:2379', 'scope': 'test', 'name': 'foo'})
def test_base_path(self):
self.assertEqual(self.etcd._base_path, '/patroni/test')
@patch('dns.resolver.query', dns_query)
def test_get_etcd_client(self):
with patch('time.sleep', Mock(side_effect=SleepException)),\
patch.object(EtcdClient, 'machines') as mock_machines:
mock_machines.__get__ = Mock(side_effect=etcd.EtcdException)
self.assertRaises(SleepException, self.etcd.get_etcd_client,
{'discovery_srv': 'test', 'retry_timeout': 10, 'cacert': '1', 'key': '1', 'cert': 1},
EtcdClient)
self.assertRaises(SleepException, self.etcd.get_etcd_client,
{'url': 'https://test:2379', 'retry_timeout': 10}, EtcdClient)
self.assertRaises(SleepException, self.etcd.get_etcd_client,
{'hosts': 'foo:4001,bar', 'retry_timeout': 10}, EtcdClient)
mock_machines.__get__ = Mock(return_value=[])
self.assertRaises(SleepException, self.etcd.get_etcd_client,
{'proxy': 'https://user:password@test:2379', 'retry_timeout': 10}, EtcdClient)
def test_get_cluster(self):
cluster = self.etcd.get_cluster()
self.assertIsInstance(cluster, Cluster)
self.assertFalse(cluster.is_synchronous_mode())
self.etcd._base_path = '/service/legacy'
self.assertIsInstance(self.etcd.get_cluster(), Cluster)
self.etcd._base_path = '/service/broken'
self.assertIsInstance(self.etcd.get_cluster(), Cluster)
self.etcd._base_path = '/service/nocluster'
cluster = self.etcd.get_cluster()
self.assertIsInstance(cluster, Cluster)
self.assertIsNone(cluster.leader)
self.etcd._base_path = '/service/noleader'
self.assertRaises(EtcdError, self.etcd.get_cluster)
def test_touch_member(self):
self.assertFalse(self.etcd.touch_member('', ''))
def test_take_leader(self):
self.assertFalse(self.etcd.take_leader())
def test_attempt_to_acquire_leader(self):
self.etcd._base_path = '/service/exists'
self.assertFalse(self.etcd.attempt_to_acquire_leader())
self.etcd._base_path = '/service/failed'
self.assertFalse(self.etcd.attempt_to_acquire_leader())
def test_write_leader_optime(self):
self.etcd.write_leader_optime('0')
def test_update_leader(self):
self.assertTrue(self.etcd.update_leader(None))
def test_initialize(self):
self.assertFalse(self.etcd.initialize())
def test_cancel_initializion(self):
self.assertFalse(self.etcd.cancel_initialization())
def test_delete_leader(self):
self.assertFalse(self.etcd.delete_leader())
def test_delete_cluster(self):
self.assertFalse(self.etcd.delete_cluster())
@patch('time.sleep', Mock(side_effect=SleepException))
@patch.object(etcd.Client, 'watch', etcd_watch)
def test_watch(self):
self.etcd.watch(None, 0)
self.etcd.get_cluster()
self.etcd.watch(20729, 1.5)
with patch('time.sleep', Mock()):
self.etcd.watch(20729, 4.5)
with patch.object(AbstractDCS, 'watch', Mock()):
self.assertTrue(self.etcd.watch(20729, 19.5))
self.assertRaises(SleepException, self.etcd.watch, 20729, 9.5)
def test_other_exceptions(self):
self.etcd.retry = Mock(side_effect=AttributeError('foo'))
self.assertRaises(EtcdError, self.etcd.cancel_initialization)
def test_set_ttl(self):
self.etcd.set_ttl(20)
self.assertTrue(self.etcd.watch(None, 1))
def test_sync_state(self):
self.assertFalse(self.etcd.write_sync_state('leader', None))
self.assertFalse(self.etcd.delete_sync_state())
def test_set_history_value(self):
self.assertFalse(self.etcd.set_history_value('{}'))