class Patroni:
def __init__(self, config):
self.nap_time = config['loop_wait']
self.postgresql = Postgresql(config['postgresql'])
self.ha = Ha(self.postgresql, self.get_dcs(self.postgresql.name, config))
host, port = config['restapi']['listen'].split(':')
self.api = RestApiServer(self, config['restapi'])
self.next_run = time.time()
self.shutdown_member_ttl = 300
@staticmethod
def get_dcs(name, config):
if 'etcd' in config:
return Etcd(name, config['etcd'])
if 'zookeeper' in config:
return ZooKeeper(name, config['zookeeper'])
raise Exception('Can not find sutable configuration of distributed configuration store')
def touch_member(self, ttl=None):
connection_string = self.postgresql.connection_string + '?application_name=' + self.api.connection_string
if self.ha.cluster:
for m in self.ha.cluster.members:
# Do not update member TTL when it is far from being expired
if m.name == self.postgresql.name and m.real_ttl() > self.shutdown_member_ttl:
return True
return self.ha.dcs.touch_member(connection_string, ttl)
def cleanup_on_failed_initialization(self):
""" cleanup the DCS if initialization was not successfull """
logger.info("removing initialize key after failed attempt to initialize the cluster")
self.ha.dcs.cancel_initialization()
self.touch_member(self.shutdown_member_ttl)
self.postgresql.stop()
self.postgresql.move_data_directory()
def initialize(self):
# wait for etcd to be available
while not self.touch_member():
logger.info('waiting on DCS')
sleep(5)
# is data directory empty?
if self.postgresql.data_directory_empty():
while True:
try:
cluster = self.ha.dcs.get_cluster()
if not cluster.is_unlocked(): # the leader already exists
if not cluster.initialize:
self.ha.dcs.initialize()
self.postgresql.bootstrap(cluster.leader)
break
# racing to initialize
elif not cluster.initialize and self.ha.dcs.initialize():
try:
self.postgresql.bootstrap()
except:
# bail out and clean the initialize flag.
self.cleanup_on_failed_initialization()
raise
self.ha.dcs.take_leader()
break
except DCSError:
logger.info('waiting on DCS')
sleep(5)
elif self.postgresql.is_running():
self.postgresql.load_replication_slots()
def schedule_next_run(self):
if self.postgresql.is_promoted:
self.next_run = time.time()
self.next_run += self.nap_time
current_time = time.time()
nap_time = self.next_run - current_time
if nap_time <= 0:
self.next_run = current_time
else:
self.ha.dcs.watch(nap_time)
def run(self):
self.api.start()
self.next_run = time.time()
while True:
self.touch_member()
logger.info(self.ha.run_cycle())
try:
if self.ha.state_handler.is_leader():
self.ha.cluster and self.ha.state_handler.create_replication_slots(self.ha.cluster)
else:
self.ha.state_handler.drop_replication_slots()
except:
logger.exception('Exception when changing replication slots')
reap_children()
self.schedule_next_run()
