for network connectivity check

evertlistener.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import sys
import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)

from scapy.all import traceroute
import fcntl, sys

target = ["8.8.8.8"]
logdir = "app_heartbeat.log"

pid_file = '/var/run/eventlistener.pid'

def main():
    logger = logging.getLogger('app_heartbeat')
    hdlr = logging.FileHandler(logdir)
    formatter = logging.Formatter('%(asctime)s %(levelname)s %(message)s')
    hdlr.setFormatter(formatter)
    logger.addHandler(hdlr)
    logger.setLevel(logging.INFO)
    fp = open(pid_file, 'w')

    try:
        fcntl.lockf(fp, fcntl.LOCK_EX | fcntl.LOCK_NB)
    except IOError:
        # another instance is running
        sys.exit(0)

    try:
        result, unans = traceroute(target, maxttl=6, verbose=False)
        if not result:
            print ("restricted")
            logger.info("Network down, restarting app...")
            os.system("supervisorctl restart app")
            exit()
        else:
            print ("connected")
            logger.info("Network up.")
            exit()
    except :
        pass

if __name__ == '__main__':
    main()