在Linux启动期间自动启动和停止APScheduler？

Question

How to automatic start and stop the Python APScheduler during Linux boot (Centos in my case), and stop it during shutdown?

I can start a python script during boot in linux, but then how to stop it? (remember the PID?)

And I am wondering if that is the way to go, as I want to have an easy deployment, such that developers can easily update the files in test/production and restart the scheduler, without becoming a root such that they can start/stop the service.

Currently I have the scheduler started/stopped by using tmux, which works, but I can't seem to find a good way to improve that such that during a server start/stop it's automatically started/stopped and easy updated during a deployment :(

Answer 1

It's usual to create a file with extension .pid to hold the process PID. Then you need to register a signal handler to cleanly exit, and make sure you delete the .pid file at exit.

For example:

#!/usr/bin/env python

import signal
import atexit
import os

PID_FILE_PATH = "program.pid"
stop = False

def create_pid_file():
    # this creates a file called program.pid
    with open(PID_FILE_PATH, "w") as fhandler:
        # and stores the PID in it
        fhandler.write(str(os.getpid()))

def sigint_handler(signum, frame):
    print("Cleanly exiting")
    global stop

    # this will break the main loop
    stop = True

def exit_handler():
    # delete PID file
    os.unlink(PID_FILE_PATH)

def main():
    create_pid_file()

    # this makes exit_handler to be called automatically when the program exists
    atexit.register(exit_handler)

    # this makes sigint_handler to be called when a signal SIGTERM 
    # is sent to the process, e.g with command: kill -SIGTERM $PID
    signal.signal(signal.SIGTERM, sigint_handler)

    while not stop:
        # this represents your main loop
        pass

if __name__ == "__main__":
    main()