Use ZooKeeper to lock resources with a Python script.
Create lock_example.py Python script.
#!/usr/bin/env python3
import argparse
import time
from datetime import datetime
from kazoo.client import KazooClient
class ApplicationNode(object):
lock_time: int
def __init__(self, chroot, lock_path, lock_identifier, lock_time, zookeeper_hosts):
self.zookeeper = KazooClient(hosts=zookeeper_hosts)
self.patch_chroot = chroot
self.lock_path = lock_path
self.lock_identifier = lock_identifier
self.lock_time = lock_time
self.connect()
self.chroot()
def connect(self):
self.zookeeper.start()
def chroot(self):
self.zookeeper.ensure_path(self.patch_chroot)
self.zookeeper.chroot = self.patch_chroot
def lock(self):
lock = self.zookeeper.Lock(self.lock_path, self.lock_identifier)
with lock:
print("At {0} the {1} got lock {2} (will sleep for {3}s)".format(
(datetime.now()).strftime("%B %d, %Y %H:%M:%S"), self.lock_identifier,
self.lock_path,
self.lock_time)
)
time.sleep(self.lock_time)
def __del__(self):
self.zookeeper.close()
if __name__ == '__main__':
parser = argparse.ArgumentParser(description='ZooKeeper example application')
parser.add_argument('--chroot')
parser.add_argument('--path')
parser.add_argument('--identifier')
parser.add_argument('--time', type=int)
parser.add_argument('--zookeeper')
args = parser.parse_args()
locker = ApplicationNode(lock_path=args.path, lock_identifier=args.identifier, chroot=args.chroot,
lock_time=args.time, zookeeper_hosts=args.zookeeper)
while True:
locker.lock()
Use it to play with locks for a particular resource.
$ python3 lock_example.py --chroot /sleeper_app --identifier client_1 --path /particular_resource --time 10 --zookeeper 172.16.0.111:2181,172.16.0.112:2181,172.16.0.113:2181
At June 15, 2021 23:17:16 the client_1 got lock /particular_resource (will sleep for 10s) At June 15, 2021 23:17:46 the client_1 got lock /particular_resource (will sleep for 10s) At June 15, 2021 23:18:16 the client_1 got lock /particular_resource (will sleep for 10s) At June 15, 2021 23:18:46 the client_1 got lock /particular_resource (will sleep for 10s) At June 15, 2021 23:19:16 the client_1 got lock /particular_resource (will sleep for 10s) At June 15, 2021 23:19:46 the client_1 got lock /particular_resource (will sleep for 10s) At June 15, 2021 23:20:12 the client_1 got lock /particular_resource (will sleep for 10s) ^C
$ python3 lock_example.py --chroot /sleeper_app --identifier client_2 --path /particular_resource --time 15 --zookeeper 172.16.0.111:2181,172.16.0.112:2181,172.16.0.113:2181
At June 15, 2021 23:17:26 the client_2 got lock /particular_resource (will sleep for 15s) At June 15, 2021 23:17:56 the client_2 got lock /particular_resource (will sleep for 15s) At June 15, 2021 23:18:26 the client_2 got lock /particular_resource (will sleep for 15s) At June 15, 2021 23:18:56 the client_2 got lock /particular_resource (will sleep for 15s) At June 15, 2021 23:19:26 the client_2 got lock /particular_resource (will sleep for 15s) At June 15, 2021 23:19:56 the client_2 got lock /particular_resource (will sleep for 15s) ^C
$ python3 lock_example.py --chroot /sleeper_app --identifier client_3 --path /particular_resource --time 5 --zookeeper 172.16.0.111:2181,172.16.0.112:2181,172.16.0.113:2181
At June 15, 2021 23:17:41 the client_3 got lock /particular_resource (will sleep for 5s) At June 15, 2021 23:18:11 the client_3 got lock /particular_resource (will sleep for 5s) At June 15, 2021 23:18:41 the client_3 got lock /particular_resource (will sleep for 5s) At June 15, 2021 23:19:11 the client_3 got lock /particular_resource (will sleep for 5s) At June 15, 2021 23:19:41 the client_3 got lock /particular_resource (will sleep for 5s) At June 15, 2021 23:20:11 the client_3 got lock /particular_resource (will sleep for 5s) ^C
Beware, the error handling is missing to keep this example more concise.