docker容器内的Python，优雅地停止

Question

我正在 Windows docker 容器 中运行一个非常基本的 Python 循环示例，我想优雅地停止。

脚本在我的 dockerfile 中以这种方式启动：

CMD [ "python.exe" , "./test.py"]

在 docker 文档中，据说 SIGTERM 信号已发送到主命令，所以我试图以这种方式捕捉它：

import signal
import time
import logging, sys

class GracefulKiller:
  kill_now = False
  def __init__(self):
    signal.signal(signal.SIGINT, self.exit_gracefully)
    signal.signal(signal.SIGTERM, self.exit_gracefully)

  def exit_gracefully(self,signum, frame):
    self.kill_now = True

if __name__ == '__main__':
  logging.basicConfig(stream=sys.stdout, level=logging.DEBUG)
  killer = GracefulKiller()
  while True:
    time.sleep(1)
    logging.info("doing something in a loop ...")
    if killer.kill_now:
      break

  logging.info("End of the program. I was killed gracefully :)")

理论上，信号应该被处理程序捕获，布尔值应该切换，循环应该退出并显示我最后的日志行。它没有，它只是在信号发出的那一刻停止整个事情（或者更确切地说是 2-3 秒后）

C:\Users\Administrator\Documents\Projects\test>docker-compose up
Recreating test_1 ... done
Attaching to test_1
test_1  | INFO:root:doing something in a loop ...
test_1  | INFO:root:doing something in a loop ...
test_1  | INFO:root:doing something in a loop ...
test_1  | INFO:root:doing something in a loop ...
test_1  | INFO:root:doing something in a loop ...
test_1  | INFO:root:doing something in a loop ...
test_1  | INFO:root:doing something in a loop ...
test_1  | INFO:root:doing something in a loop ...
test_1  | INFO:root:doing something in a loop ...
test_1  | INFO:root:doing something in a loop ...
test_1  | INFO:root:doing something in a loop ...
test_1  | INFO:root:doing something in a loop ...
test_1  | INFO:root:doing something in a loop ...
test_1  | INFO:root:doing something in a loop ...
Gracefully stopping... (press Ctrl+C again to force)
Stopping test_1   ... done

我的最后一行日志从未到达。 有谁知道发生了什么？它是特定于 python 的问题，特定于 docker 还是特定于 Windows？

我还尝试使用 docker 日志检查已停止的容器，最后一个日志也不在这里。尝试在其后添加睡眠，结果相同。

谢谢，

Answer 1

当在当前版本中使用 docker-compose up 时，这似乎仍然普遍存在，我整个早上都在 Raspbian 上进行调查（并把我带到这里）。

但是，使用docker-compose 2.1.1 通过docker-compose up 使用以下配置运行您的示例表明实际调用了您的python 代码的最后一行，您只是看不到它：

docker-compose.yaml

services:
  grace_test:
    container_name: grace_test
    build: .

Dockerfile

FROM python:3.8-slim-buster

# setup WORKDIR
ADD . /grace_test
WORKDIR /grace_test
CMD ["python", "test.py"]

test.py

import signal
import time
import logging, sys

class GracefulKiller:
  kill_now = False
  def __init__(self):
    signal.signal(signal.SIGINT, self.exit_gracefully)
    signal.signal(signal.SIGTERM, self.exit_gracefully)

  def exit_gracefully(self,signum, frame):
    self.kill_now = True

if __name__ == '__main__':
  logging.basicConfig(stream=sys.stdout, level=logging.DEBUG)
  killer = GracefulKiller()
  while True:
    time.sleep(1)
    logging.info("doing something in a loop ...")
    if killer.kill_now:
      break

  logging.info("End of the program. I was killed gracefully :)")

验证

使用docker-compose logs检查Ctrl-C之后的日志：

$ docker-compose logs
grace_test  | INFO:root:doing something in a loop ...
grace_test  | INFO:root:doing something in a loop ...
grace_test  | INFO:root:doing something in a loop ...
grace_test  | INFO:root:doing something in a loop ...
grace_test  | INFO:root:End of the program. I was killed gracefully :)

Answer 2

只要抓住KeyboardInterrupt就可以了。

if __name__ == '__main__':
  logging.basicConfig(stream=sys.stdout, level=logging.DEBUG)
  try:
    while True:
      time.sleep(1)
      logging.info("doing something in a loop ...")
  except KeyboardInterrupt as ex:
    print('goodbye!')