mirror of
https://github.com/outbackdingo/patroni.git
synced 2026-08-25 14:53:37 +00:00
88 lines
3.8 KiB
Python
88 lines
3.8 KiB
Python
import sys, time, re, urllib2, json, psycopg2
|
|
from base64 import b64decode
|
|
|
|
import helpers.errors
|
|
|
|
import inspect
|
|
|
|
def lineno():
|
|
"""Returns the current line number in our program."""
|
|
return inspect.currentframe().f_back.f_lineno
|
|
|
|
class Ha:
|
|
def __init__(self, state_handler, etcd):
|
|
self.state_handler = state_handler
|
|
self.etcd = etcd
|
|
|
|
def acquire_lock(self):
|
|
return self.etcd.attempt_to_acquire_leader(self.state_handler.name)
|
|
|
|
def update_lock(self):
|
|
return self.etcd.update_leader(self.state_handler.name)
|
|
|
|
def is_unlocked(self):
|
|
return self.etcd.leader_unlocked()
|
|
|
|
def has_lock(self):
|
|
return self.etcd.am_i_leader(self.state_handler.name)
|
|
|
|
def fetch_current_leader(self):
|
|
return self.etcd.current_leader()
|
|
|
|
def run_cycle(self):
|
|
try:
|
|
if self.state_handler.is_healthy():
|
|
if self.is_unlocked():
|
|
if self.state_handler.is_healthiest_node(self.etcd.members()):
|
|
if self.acquire_lock():
|
|
if not self.state_handler.is_leader():
|
|
self.state_handler.promote()
|
|
return "promoted self to leader by acquiring session lock"
|
|
|
|
return "acquired session lock as a leader"
|
|
else:
|
|
if self.state_handler.is_leader():
|
|
self.state_handler.demote(self.fetch_current_leader())
|
|
return "demoted self due after trying and failing to obtain lock"
|
|
else:
|
|
self.state_handler.follow_the_leader(self.fetch_current_leader())
|
|
return "following new leader after trying and failing to obtain lock"
|
|
else:
|
|
if self.state_handler.is_leader():
|
|
self.state_handler.demote(self.fetch_current_leader())
|
|
return "demoting self because i am not the healthiest node"
|
|
else:
|
|
self.state_handler.follow_the_leader(self.fetch_current_leader())
|
|
return "following a different leader because i am not the healthiest node"
|
|
|
|
else:
|
|
if self.has_lock():
|
|
self.update_lock()
|
|
|
|
if not self.state_handler.is_leader():
|
|
self.state_handler.promote()
|
|
return "promoted self to leader because i had the session lock"
|
|
else:
|
|
return "no action. i am the leader with the lock"
|
|
else:
|
|
print "does not have lock"
|
|
if self.state_handler.is_leader():
|
|
self.state_handler.demote(self.fetch_current_leader())
|
|
return "demoting self because i do not have the lock and i was a leader"
|
|
else:
|
|
self.state_handler.follow_the_leader(self.fetch_current_leader())
|
|
return "no action. i am a secondary and i am following a leader"
|
|
else:
|
|
return "no action. not healthy enough to do anything."
|
|
except helpers.errors.CurrentLeaderError:
|
|
print "failed to fetch current leader from etcd"
|
|
except psycopg2.OperationalError:
|
|
print "Error communicating with Postgresql. Will try again."
|
|
except helpers.errors.HealthiestMemberError:
|
|
print "failed to determine healthiest member fromt etcd"
|
|
|
|
def run(self):
|
|
while True:
|
|
self.run_cycle()
|
|
time.sleep(10)
|