a stupid watch dog

watchdog.py

#!/usr/bin/env python3
"""
run this to keep the watchdog happy

curl localhost:8080

or from js

setInterval(function(){ fetch("localhost:8080"); }, 3000);

"""


from http.server import BaseHTTPRequestHandler, HTTPServer
import time
import threading
from subprocess import run

hostName = "localhost"
serverPort = 8080

last_check = time.time()  # Last time watchdog was poked
max_watchdog_time = 10  # How long to wait before running shell command

def watchdog_target():
    global last_check
    print("watchdog thread is running")
    while True:
        if time.time() - last_check > max_watchdog_time:
            print("Watchdog not happy, last poke was >{}s ago".format(max_watchdog_time))
            run("echo 'a command'", shell=True)
            time.sleep(10)
        time.sleep(1)


class MyServer(BaseHTTPRequestHandler):
    def do_GET(self):
        global last_check
        last_check = time.time()
        self.send_response(200)
        self.send_header("Content-type", "text/plain")
        self.send_header("Access-Control-Allow-Origin", "*")
        self.end_headers()
        self.wfile.write(bytes("Watchdog is happy!\n", "utf-8"))

if __name__ == "__main__":
    webServer = HTTPServer((hostName, serverPort), MyServer)
    print("Server started http://%s:%s" % (hostName, serverPort))

    watchdog_thread = threading.Thread(target=watchdog_target, daemon=True)
    watchdog_thread.start()

    try:
        webServer.serve_forever()
    except KeyboardInterrupt:
        pass

    webServer.server_close()
    print("Server stopped.")