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Fix manual failover/switchover checks (#2769)

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In case of manual failover/switchover failover possibility should be checked only against the candidate
This commit is contained in:
Polina Bungina
2023-07-24 16:23:18 +02:00
committed by GitHub
parent 48164774c2
commit e860cac348
1 changed files with 30 additions and 8 deletions
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patroni/ha.py
+30 -8
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@@ -1085,7 +1085,9 @@ class Ha(object):
# It could happen if Postgres is still archiving the backlog of WAL files.
# If we know that there are replicas that received the shutdown checkpoint
# location, we can remove the leader key and allow them to start leader race.
if self.is_failover_possible(self.cluster.members, cluster_lsn=checkpoint_location):
# for a manual failover/switchover with a candidate, we should check the requested candidate only
if self.is_failover_possible(self.get_failover_candidates(), cluster_lsn=checkpoint_location):
self.state_handler.set_role('demoted')
with self._async_executor:
self.release_leader_key_voluntarily(checkpoint_location)
@@ -1189,15 +1191,12 @@ class Ha(object):
logger.warning('Failover is possible only to a specific candidate in a paused state')
else:
if self.is_synchronous_mode():
if failover.candidate and not self.cluster.sync.matches(failover.candidate):
members = self.get_failover_candidates(check_sync=True)
if failover.candidate and not members:
logger.warning('Failover candidate=%s does not match with sync_standbys=%s',
failover.candidate, self.cluster.sync.sync_standby)
members = []
else:
members = [m for m in self.cluster.members if self.cluster.sync.matches(m.name)]
else:
members = [m for m in self.cluster.members
if not failover.candidate or m.name == failover.candidate]
members = self.get_failover_candidates()
if self.is_failover_possible(members, False): # check that there are healthy members
ret = self._async_executor.try_run_async('manual failover: demote', self.demote, ('graceful',))
return ret or 'manual failover: demoting myself'
@@ -1849,7 +1848,9 @@ class Ha(object):
# It could happen if Postgres is still archiving the backlog of WAL files.
# If we know that there are replicas that received the shutdown checkpoint
# location, we can remove the leader key and allow them to start leader race.
if self.is_failover_possible(self.cluster.members, cluster_lsn=checkpoint_location):
# for a manual failover/switchover with a candidate, we should check the requested candidate only
if self.is_failover_possible(self.get_failover_candidates(), cluster_lsn=checkpoint_location):
self.dcs.delete_leader(checkpoint_location)
status['deleted'] = True
else:
@@ -1909,3 +1910,24 @@ class Ha(object):
name = member.name if member else 'remote_member:{}'.format(uuid.uuid1())
return RemoteMember.from_name_and_data(name, data)
def get_failover_candidates(self, check_sync: bool = False) -> List[Member]:
"""Return list of candidates for either manual or automatic failover.
Mainly used to later be passed to ``Ha.is_failover_possible()``.
:param check_sync: if ``True``, also check against the sync key members
:returns: a list of ``Member`` ojects or an empty list if there is no candidate available
"""
failover = self.cluster.failover
if check_sync:
# TODO: allow manual failover (=no leader specified) to async node
# every sync_standby or the candidate specified if is in sync_standbys
return [m for m in self.cluster.members
if self.cluster.sync.matches(m.name)
and (not failover or not failover.candidate or m.name == failover.candidate)]
else:
# every member or the candidate specified
return [m for m in self.cluster.members
if not failover or not failover.candidate or m.name == failover.candidate]