A Script for Executing Command when Ping is Failed

restarter.py

#!/usr/bin/env python3


import os
import sys
import time
import subprocess


from optparse import OptionParser

from logging import getLogger, DEBUG, StreamHandler, Formatter
from logging.handlers import SysLogHandler
logger = getLogger(__name__)
logger.setLevel(DEBUG)
stream = StreamHandler()
syslog = SysLogHandler(address = "/dev/log")
syslog.setFormatter(Formatter("restarter: %(message)s"))
logger.addHandler(stream)
logger.addHandler(syslog)
logger.propagate = False


        
def lets_ping(target, count) :

    success = None

    for x in range(count) :
        try :
            subprocess.check_call([ "/bin/ping", "-W", "1", "-c", "1", target])
            success = True
            time.sleep(0.2)
        except Exception as e:
            logger.error("Ping Failed to %s" % target)
            logger.error(e)
        
    if not success :
        logger.error("%d pings to %s failed!" % (count, target))
        return False
    else :
        return True


def loop(option) :

    restart_time = 0

    while True :

        time.sleep(option.interval)


        if lets_ping(option.target, option.count) :
            restart_time = 0

        else :

            wait_left = option.wait - (int(time.time() - restart_time))

            if restart_time and wait_left > 0 :
                logger.info("Pings Failed, but in wait time, %d sec left" %
                            wait_left)
                continue

            try :
                logger.error("Start to execute '%s'" % option.cmd)
                output = subprocess.check_output(option.cmd.split())
                logger.info(output)
                
            except Exception as e:
                logger.error("Execution Failed: '%s'" % option.cmd)
                logger.error(e)
            
            restart_time = int(time.time())




def main() :

    desc = "usage: %prog [options]"
    parser = OptionParser(desc)

    parser.add_option(
        "--cmd", type = "string", default = False, dest = "cmd",
        help = "command string for when ping failed"
    )
    parser.add_option(
        "--target", type = "string", default = False, dest = "target",
        help = "ping target"
    )
    parser.add_option(
        "--count", type = "int", default = 5, dest = "count",
        help = "ping count for one check"
    )
    parser.add_option(
        "--interval", type = "int", default = 120, dest = "interval",
        help = "check interval (sec)"
    )
    parser.add_option(
        "--wait", type = "int", default = 240, dest = "wait",
        help = "wait time after restart (sec)"
    )

    (option, args) = parser.parse_args()

    if not option.cmd :
        print("execution command is required")
        sys.exit(1)

    if not option.target :
        print("ping target is reequired")
        sys.exit(1)
    
    loop(option)


if __name__ == "__main__" :

    main()