gitops/patroni
1
0
Fork 0
mirror of https://github.com/outbackdingo/patroni.git synced 2026-08-25 14:53:37 +00:00
Code Issues Packages Projects Releases Wiki Activity
Files
384705ad97549bf3863a7b74f2d4fc94bfdbcecc
patroni/tests/test_quorum.py
T
Alexander KukushkinandGitHub 384705ad97 Quorum based failover (#2668) 
To enable quorum commit:
```diff
$ patronictl.py edit-config
--- 
+++ 
@@ -5,3 +5,4 @@
   use_pg_rewind: true
 retry_timeout: 10
 ttl: 30
+synchronous_mode: quorum

Apply these changes? [y/N]: y
Configuration changed
```

By default Patroni will use `ANY 1(list,of,stanbys)` in `synchronous_standby_names`. That is, only one node out of listed replicas will be used for quorum.
If you want to increase the number of quorum nodes it is possible to do it with:
```diff
$ patronictl edit-config
--- 
+++ 
@@ -6,3 +6,4 @@
 retry_timeout: 10
 synchronous_mode: quorum
 ttl: 30
+synchronous_node_count: 2

Apply these changes? [y/N]: y
Configuration changed
```

Good old `synchronous_mode: on` is still supported.

Close https://github.com/patroni/patroni/issues/664
Close https://github.com/zalando/patroni/pull/672
2024-08-13 08:51:01 +02:00

474 lines
25 KiB
Python
Raw Blame History

import unittest
from typing import List, Set, Tuple
from patroni.quorum import QuorumStateResolver, QuorumError
class QuorumTest(unittest.TestCase):
def check_state_transitions(self, leader: str, quorum: int, voters: Set[str], numsync: int, sync: Set[str],
numsync_confirmed: int, active: Set[str], sync_wanted: int, leader_wanted: str,
expected: List[Tuple[str, str, int, Set[str]]]) -> None:
kwargs = {
'leader': leader, 'quorum': quorum, 'voters': voters,
'numsync': numsync, 'sync': sync, 'numsync_confirmed': numsync_confirmed,
'active': active, 'sync_wanted': sync_wanted, 'leader_wanted': leader_wanted
}
result = list(QuorumStateResolver(**kwargs))
self.assertEqual(result, expected)
# also check interrupted transitions
if len(result) > 0 and result[0][0] != 'restart' and kwargs['leader'] == result[0][1]:
if result[0][0] == 'sync':
kwargs.update(numsync=result[0][2], sync=result[0][3])
else:
kwargs.update(leader=result[0][1], quorum=result[0][2], voters=result[0][3])
kwargs['expected'] = expected[1:]
self.check_state_transitions(**kwargs)
def test_1111(self):
leader = 'a'
# Add node
self.check_state_transitions(leader=leader, quorum=0, voters=set(),
numsync=0, sync=set(), numsync_confirmed=0, active=set('b'),
sync_wanted=2, leader_wanted=leader, expected=[
('sync', leader, 1, set('b')),
('restart', leader, 0, set()),
])
self.check_state_transitions(leader=leader, quorum=0, voters=set(),
numsync=1, sync=set('b'), numsync_confirmed=1, active=set('b'),
sync_wanted=2, leader_wanted=leader, expected=[
('quorum', leader, 0, set('b'))
])
self.check_state_transitions(leader=leader, quorum=0, voters=set(),
numsync=0, sync=set(), numsync_confirmed=0, active=set('bcde'),
sync_wanted=2, leader_wanted=leader, expected=[
('sync', leader, 2, set('bcde')),
('restart', leader, 0, set()),
])
self.check_state_transitions(leader=leader, quorum=0, voters=set(),
numsync=2, sync=set('bcde'), numsync_confirmed=1, active=set('bcde'),
sync_wanted=2, leader_wanted=leader, expected=[
('quorum', leader, 3, set('bcde')),
])
def test_1222(self):
"""2 node cluster"""
leader = 'a'
# Active set matches state
self.check_state_transitions(leader=leader, quorum=0, voters=set('b'),
numsync=1, sync=set('b'), numsync_confirmed=1, active=set('b'),
sync_wanted=2, leader_wanted=leader, expected=[])
# Add node by increasing quorum
self.check_state_transitions(leader=leader, quorum=0, voters=set('b'),
numsync=1, sync=set('b'), numsync_confirmed=1, active=set('BC'),
sync_wanted=1, leader_wanted=leader, expected=[
('quorum', leader, 1, set('bC')),
('sync', leader, 1, set('bC')),
])
# Add node by increasing sync
self.check_state_transitions(leader=leader, quorum=0, voters=set('b'),
numsync=1, sync=set('b'), numsync_confirmed=1, active=set('bc'),
sync_wanted=2, leader_wanted=leader, expected=[
('sync', leader, 2, set('bc')),
('quorum', leader, 1, set('bc')),
])
# Reduce quorum after added node caught up
self.check_state_transitions(leader=leader, quorum=1, voters=set('bc'),
numsync=2, sync=set('bc'), numsync_confirmed=2, active=set('bc'),
sync_wanted=2, leader_wanted=leader, expected=[
('quorum', leader, 0, set('bc')),
])
# Add multiple nodes by increasing both sync and quorum
self.check_state_transitions(leader=leader, quorum=0, voters=set('b'),
numsync=1, sync=set('b'), numsync_confirmed=1, active=set('BCdE'),
sync_wanted=2, leader_wanted=leader, expected=[
('sync', leader, 2, set('bC')),
('quorum', leader, 3, set('bCdE')),
('sync', leader, 2, set('bCdE')),
])
# Reduce quorum after added nodes caught up
self.check_state_transitions(leader=leader, quorum=3, voters=set('bcde'),
numsync=2, sync=set('bcde'), numsync_confirmed=3, active=set('bcde'),
sync_wanted=2, leader_wanted=leader, expected=[
('quorum', leader, 2, set('bcde')),
])
# Primary is alone
self.check_state_transitions(leader=leader, quorum=0, voters=set('b'),
numsync=1, sync=set('b'), numsync_confirmed=0, active=set(),
sync_wanted=1, leader_wanted=leader, expected=[
('quorum', leader, 0, set()),
('sync', leader, 0, set()),
])
# Swap out sync replica
self.check_state_transitions(leader=leader, quorum=0, voters=set('b'),
numsync=1, sync=set('b'), numsync_confirmed=0, active=set('c'),
sync_wanted=1, leader_wanted=leader, expected=[
('quorum', leader, 0, set()),
('sync', leader, 1, set('c')),
('restart', leader, 0, set()),
])
# Update quorum when added node caught up
self.check_state_transitions(leader=leader, quorum=0, voters=set(),
numsync=1, sync=set('c'), numsync_confirmed=1, active=set('c'),
sync_wanted=1, leader_wanted=leader, expected=[
('quorum', leader, 0, set('c')),
])
def test_1233(self):
"""Interrupted transition from 2 node cluster to 3 node fully sync cluster"""
leader = 'a'
# Node c went away, transition back to 2 node cluster
self.check_state_transitions(leader=leader, quorum=0, voters=set('b'),
numsync=2, sync=set('bc'), numsync_confirmed=1, active=set('b'),
sync_wanted=2, leader_wanted=leader, expected=[
('sync', leader, 1, set('b')),
])
# Node c is available transition to larger quorum set, but not yet caught up.
self.check_state_transitions(leader=leader, quorum=0, voters=set('b'),
numsync=2, sync=set('bc'), numsync_confirmed=1, active=set('bc'),
sync_wanted=2, leader_wanted=leader, expected=[
('quorum', leader, 1, set('bc')),
])
# Add in a new node at the same time, but node c didn't caught up yet
self.check_state_transitions(leader=leader, quorum=0, voters=set('b'),
numsync=2, sync=set('bc'), numsync_confirmed=1, active=set('bcd'),
sync_wanted=2, leader_wanted=leader, expected=[
('quorum', leader, 2, set('bcd')),
('sync', leader, 2, set('bcd')),
])
# All sync nodes caught up, reduce quorum
self.check_state_transitions(leader=leader, quorum=2, voters=set('bcd'),
numsync=2, sync=set('bcd'), numsync_confirmed=3, active=set('bcd'),
sync_wanted=2, leader_wanted=leader, expected=[
('quorum', leader, 1, set('bcd')),
])
# Change replication factor at the same time
self.check_state_transitions(leader=leader, quorum=0, voters=set('b'),
numsync=2, sync=set('bc'), numsync_confirmed=1, active=set('bc'),
sync_wanted=1, leader_wanted=leader, expected=[
('quorum', leader, 1, set('bc')),
('sync', leader, 1, set('bc')),
])
def test_2322(self):
"""Interrupted transition from 2 node cluster to 3 node cluster with replication factor 2"""
leader = 'a'
# Node c went away, transition back to 2 node cluster
self.check_state_transitions(leader=leader, quorum=1, voters=set('bc'),
numsync=1, sync=set('b'), numsync_confirmed=1, active=set('b'),
sync_wanted=1, leader_wanted=leader, expected=[
('quorum', leader, 0, set('b')),
])
# Node c is available transition to larger quorum set.
self.check_state_transitions(leader=leader, quorum=1, voters=set('bc'),
numsync=1, sync=set('b'), numsync_confirmed=1, active=set('bc'),
sync_wanted=1, leader_wanted=leader, expected=[
('sync', leader, 1, set('bc')),
])
# Add in a new node at the same time
self.check_state_transitions(leader=leader, quorum=1, voters=set('bc'),
numsync=1, sync=set('b'), numsync_confirmed=1, active=set('bcd'),
sync_wanted=1, leader_wanted=leader, expected=[
('sync', leader, 1, set('bc')),
('quorum', leader, 2, set('bcd')),
('sync', leader, 1, set('bcd')),
])
# Convert to a fully synced cluster
self.check_state_transitions(leader=leader, quorum=1, voters=set('bc'),
numsync=1, sync=set('b'), numsync_confirmed=1, active=set('bc'),
sync_wanted=2, leader_wanted=leader, expected=[
('sync', leader, 2, set('bc')),
])
# Reduce quorum after all nodes caught up
self.check_state_transitions(leader=leader, quorum=1, voters=set('bc'),
numsync=2, sync=set('bc'), numsync_confirmed=2, active=set('bc'),
sync_wanted=2, leader_wanted=leader, expected=[
('quorum', leader, 0, set('bc')),
])
def test_3535(self):
leader = 'a'
# remove nodes
self.check_state_transitions(leader=leader, quorum=2, voters=set('bcde'),
numsync=2, sync=set('bcde'), numsync_confirmed=2, active=set('bc'),
sync_wanted=2, leader_wanted=leader, expected=[
('sync', leader, 2, set('bc')),
('quorum', leader, 0, set('bc')),
])
self.check_state_transitions(leader=leader, quorum=2, voters=set('bcde'),
numsync=2, sync=set('bcde'), numsync_confirmed=3, active=set('bcd'),
sync_wanted=2, leader_wanted=leader, expected=[
('sync', leader, 2, set('bcd')),
('quorum', leader, 1, set('bcd')),
])
# remove nodes and decrease sync
self.check_state_transitions(leader=leader, quorum=2, voters=set('bcde'),
numsync=2, sync=set('bcde'), numsync_confirmed=2, active=set('bc'),
sync_wanted=1, leader_wanted=leader, expected=[
('sync', leader, 2, set('bc')),
('quorum', leader, 1, set('bc')),
('sync', leader, 1, set('bc')),
])
self.check_state_transitions(leader=leader, quorum=1, voters=set('bcde'),
numsync=3, sync=set('bcde'), numsync_confirmed=2, active=set('bc'),
sync_wanted=1, leader_wanted=leader, expected=[
('sync', leader, 3, set('bcd')),
('quorum', leader, 1, set('bc')),
('sync', leader, 1, set('bc')),
])
# Increase replication factor and decrease quorum
self.check_state_transitions(leader=leader, quorum=2, voters=set('bcde'),
numsync=2, sync=set('bcde'), numsync_confirmed=2, active=set('bcde'),
sync_wanted=3, leader_wanted=leader, expected=[
('sync', leader, 3, set('bcde')),
])
# decrease quorum after more nodes caught up
self.check_state_transitions(leader=leader, quorum=2, voters=set('bcde'),
numsync=3, sync=set('bcde'), numsync_confirmed=3, active=set('bcde'),
sync_wanted=3, leader_wanted=leader, expected=[
('quorum', leader, 1, set('bcde')),
])
# Add node with decreasing sync and increasing quorum
self.check_state_transitions(leader=leader, quorum=2, voters=set('bcde'),
numsync=2, sync=set('bcde'), numsync_confirmed=2, active=set('bcdef'),
sync_wanted=1, leader_wanted=leader, expected=[
# increase quorum by 2, 1 for added node and another for reduced sync
('quorum', leader, 4, set('bcdef')),
# now reduce replication factor to requested value
('sync', leader, 1, set('bcdef')),
])
# Remove node with increasing sync and decreasing quorum
self.check_state_transitions(leader=leader, quorum=2, voters=set('bcde'),
numsync=2, sync=set('bcde'), numsync_confirmed=2, active=set('bcd'),
sync_wanted=3, leader_wanted=leader, expected=[
# node e removed from sync wth replication factor increase
('sync', leader, 3, set('bcd')),
# node e removed from voters with quorum decrease
('quorum', leader, 1, set('bcd')),
])
def test_remove_nosync_node(self):
leader = 'a'
self.check_state_transitions(leader=leader, quorum=0, voters=set('bc'),
numsync=2, sync=set('bc'), numsync_confirmed=1, active=set('b'),
sync_wanted=2, leader_wanted=leader, expected=[
('quorum', leader, 0, set('b')),
('sync', leader, 1, set('b'))
])
def test_swap_sync_node(self):
leader = 'a'
self.check_state_transitions(leader=leader, quorum=0, voters=set('bc'),
numsync=2, sync=set('bc'), numsync_confirmed=1, active=set('bd'),
sync_wanted=2, leader_wanted=leader, expected=[
('quorum', leader, 0, set('b')),
('sync', leader, 2, set('bd')),
('quorum', leader, 1, set('bd'))
])
def test_promotion(self):
# Beginning stat: 'a' in the primary, 1 of bcd in sync
# a fails, c gets quorum votes and promotes
self.check_state_transitions(leader='a', quorum=2, voters=set('bcd'),
numsync=0, sync=set(), numsync_confirmed=0, active=set(),
sync_wanted=1, leader_wanted='c', expected=[
('sync', 'a', 1, set('abd')), # set a and b to sync
('quorum', 'c', 2, set('abd')), # set c as a leader and move a to voters
# and stop because there are no active nodes
])
# next loop, b managed to reconnect
self.check_state_transitions(leader='c', quorum=2, voters=set('abd'),
numsync=1, sync=set('abd'), numsync_confirmed=0, active=set('b'),
sync_wanted=1, leader_wanted='c', expected=[
('sync', 'c', 1, set('b')), # remove a from sync as inactive
('quorum', 'c', 0, set('b')), # remove a from voters and reduce quorum
])
# alternative reality: next loop, no one reconnected
self.check_state_transitions(leader='c', quorum=2, voters=set('abd'),
numsync=1, sync=set('abd'), numsync_confirmed=0, active=set(),
sync_wanted=1, leader_wanted='c', expected=[
('quorum', 'c', 0, set()),
('sync', 'c', 0, set()),
])
def test_nonsync_promotion(self):
# Beginning state: 1 of bc in sync. e.g. (a primary, ssn = ANY 1 (b c))
# a fails, d sees b and c, knows that it is in sync and decides to promote.
# We include in sync state former primary increasing replication factor
# and let situation resolve. Node d ssn=ANY 1 (b c)
leader = 'd'
self.check_state_transitions(leader='a', quorum=1, voters=set('bc'),
numsync=0, sync=set(), numsync_confirmed=0, active=set(),
sync_wanted=1, leader_wanted=leader, expected=[
# Set a, b, and c to sync and increase replication factor
('sync', 'a', 2, set('abc')),
# Set ourselves as the leader and move the old leader to voters
('quorum', leader, 1, set('abc')),
# and stop because there are no active nodes
])
# next loop, b and c managed to reconnect
self.check_state_transitions(leader=leader, quorum=1, voters=set('abc'),
numsync=2, sync=set('abc'), numsync_confirmed=0, active=set('bc'),
sync_wanted=1, leader_wanted=leader, expected=[
('sync', leader, 2, set('bc')), # Remove a from being synced to.
('quorum', leader, 1, set('bc')), # Remove a from quorum
('sync', leader, 1, set('bc')), # Can now reduce replication factor back
])
# alternative reality: next loop, no one reconnected
self.check_state_transitions(leader=leader, quorum=1, voters=set('abc'),
numsync=2, sync=set('abc'), numsync_confirmed=0, active=set(),
sync_wanted=1, leader_wanted=leader, expected=[
('quorum', leader, 0, set()),
('sync', leader, 0, set()),
])
def test_invalid_states(self):
leader = 'a'
# Main invariant is not satisfied, system is in an unsafe state
resolver = QuorumStateResolver(leader=leader, quorum=0, voters=set('bc'),
numsync=1, sync=set('bc'), numsync_confirmed=1,
active=set('bc'), sync_wanted=1, leader_wanted=leader)
self.assertRaises(QuorumError, resolver.check_invariants)
self.assertEqual(list(resolver), [
('quorum', leader, 1, set('bc'))
])
# Quorum and sync states mismatched, somebody other than Patroni modified system state
resolver = QuorumStateResolver(leader=leader, quorum=1, voters=set('bc'),
numsync=2, sync=set('bd'), numsync_confirmed=1,
active=set('bd'), sync_wanted=1, leader_wanted=leader)
self.assertRaises(QuorumError, resolver.check_invariants)
self.assertEqual(list(resolver), [
('quorum', leader, 1, set('bd')),
('sync', leader, 1, set('bd')),
])
self.assertTrue(repr(resolver.sync).startswith('<CaseInsensitiveSet'))
def test_sync_high_quorum_low_safety_margin_high(self):
leader = 'a'
self.check_state_transitions(leader=leader, quorum=2, voters=set('bcdef'),
numsync=4, sync=set('bcdef'), numsync_confirmed=3, active=set('bcdef'),
sync_wanted=2, leader_wanted=leader, expected=[
('quorum', leader, 3, set('bcdef')), # Adjust quorum requirements
('sync', leader, 2, set('bcdef')), # Reduce synchronization
])
def test_quorum_update(self):
resolver = QuorumStateResolver(leader='a', quorum=1, voters=set('bc'), numsync=1, sync=set('bc'),
numsync_confirmed=1, active=set('bc'), sync_wanted=1, leader_wanted='a')
self.assertRaises(QuorumError, list, resolver.quorum_update(-1, set()))
self.assertRaises(QuorumError, list, resolver.quorum_update(1, set()))
def test_sync_update(self):
resolver = QuorumStateResolver(leader='a', quorum=1, voters=set('bc'), numsync=1, sync=set('bc'),
numsync_confirmed=1, active=set('bc'), sync_wanted=1, leader_wanted='a')
self.assertRaises(QuorumError, list, resolver.sync_update(-1, set()))
self.assertRaises(QuorumError, list, resolver.sync_update(1, set()))
def test_remove_nodes_with_decreasing_sync(self):
leader = 'a'
# Remove node with decreasing sync
self.check_state_transitions(leader=leader, quorum=1, voters=set('bcdef'),
numsync=4, sync=set('bcdef'), numsync_confirmed=2, active=set('bcd'),
sync_wanted=2, leader_wanted=leader, expected=[
# node f removed from sync
('sync', leader, 4, set('bcde')),
# nodes e and f removed from voters with quorum decrease
('quorum', leader, 1, set('bcd')),
# node e removed from sync with replication factor decrease
('sync', leader, 2, set('bcd')),
])
# Interrupted state, and node g joined
self.check_state_transitions(leader=leader, quorum=1, voters=set('bcdef'),
numsync=4, sync=set('bcde'), numsync_confirmed=2, active=set('bcdg'),
sync_wanted=2, leader_wanted=leader, expected=[
# remove nodes e and f from voters
('quorum', leader, 1, set('bcd')),
# remove node e from sync and reduce replication factor
('sync', leader, 3, set('bcd')),
# add node g to voters with quorum increase
('quorum', leader, 2, set('bcdg')),
# add node g to sync and reduce replication factor
('sync', leader, 2, set('bcdg')),
])
# node f returned
self.check_state_transitions(leader=leader, quorum=1, voters=set('bcdef'),
numsync=4, sync=set('bcde'), numsync_confirmed=2, active=set('bcdf'),
sync_wanted=2, leader_wanted=leader, expected=[
# replace node e with f in sync
('sync', leader, 4, set('bcdf')),
# remove nodes e from voters with quorum decrease
('quorum', leader, 2, set('bcdf')),
# reduce replication factor as it was requested
('sync', leader, 2, set('bcdf')),
])
# node e returned
self.check_state_transitions(leader=leader, quorum=1, voters=set('bcdef'),
numsync=4, sync=set('bcde'), numsync_confirmed=2, active=set('bcde'),
sync_wanted=2, leader_wanted=leader, expected=[
# remove nodes f from voters with quorum decrease
('quorum', leader, 2, set('bcde')),
# reduce replication factor as it was requested
('sync', leader, 2, set('bcde')),
])
# node b is also lost
self.check_state_transitions(leader=leader, quorum=1, voters=set('bcdef'),
numsync=4, sync=set('bcde'), numsync_confirmed=2, active=set('cd'),
sync_wanted=1, leader_wanted=leader, expected=[
# remove nodes b, e, and f from voters
('quorum', leader, 1, set('cd')),
# remove nodes b and e from sync with replication factor decrease
('sync', leader, 1, set('cd')),
])
def test_empty_ssn(self):
# Beginning stat: 'a' in the primary, 1 of bc in sync
# a fails, c gets quorum votes and promotes
self.check_state_transitions(leader='a', quorum=1, voters=set('bc'),
numsync=1, sync=set(), numsync_confirmed=0, active=set(),
sync_wanted=1, leader_wanted='c', expected=[
('sync', 'a', 1, set('ab')), # remove a from sync as inactive
('quorum', 'c', 1, set('ab')), # set c as a leader and move a to voters
# and stop because there are no active nodes
])
# next loop, b managed to reconnect
self.check_state_transitions(leader='c', quorum=1, voters=set('ab'),
numsync=1, sync=set('ab'), numsync_confirmed=0, active=set('b'),
sync_wanted=1, leader_wanted='c', expected=[
('sync', 'c', 1, set('b')), # remove a from sync as inactive
('quorum', 'c', 0, set('b')), # remove a from voters and reduce quorum
])
Reference in New Issue View Git Blame Copy Permalink