Python3 Watchdog to shutdown computer when power fails

watchdog.py

#!/usr/bin/python3

#Checks for hosts alive in the network.
#If all hosts are offline, assume that power has failed
#and initiate a shutdown

#Luiz Fellipe Carneiro - 01/2021

import socket
import os

#Path of shutdown detection file
ShutdownFile = "/home/fellipec/watchdog/failure.log"

#Check if a shutdown file exists
def ShutdownFileExists():
    result = False
    if os.path.isfile(ShutdownFile):
        result = True
    return(result)

# Try to connect to a socket 
def isOpen(ip,port):
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    try:
     s.connect((ip, int(port)))
     s.shutdown(2)
     return True
    except:
     return False

# Issue the shutdown command in 30 minutes
# If a shutdown was detected before, do nothing
def shutdown():
    if not ShutdownFileExists():
        command = "/usr/bin/sudo /sbin/shutdown +30 Power Failure, shutting down"
        import subprocess
        process = subprocess.Popen(command.split(), stdout=subprocess.PIPE)
        output = process.communicate()[0]
        print("Power failure. Shutting down in 30 minutes")
        #Write a file so we know later the power failure was already detected
        F = open(ShutdownFile,"w")
        F.write(str(output))
        F.close

# If a previous shutdown has detected, but now detected the hosts alive
# again, assume the power was restored and abort the shutdown, them 
# delete the shutdown detection file.
def abortshutdown():
    if ShutdownFileExists():
        command = "/usr/bin/sudo /sbin/shutdown -c Power restored, abort shut down"
        import subprocess
        process = subprocess.Popen(command.split(), stdout=subprocess.PIPE)
        output = process.communicate()[0]
        print("Power restored, aborting shutdown")
        os.remove(ShutdownFile)



#Device list
DeviceList = [
    ("192.168.100.44",80), #Epson printer
    ("echodot.lan",1080), #Alexa
]

#Default no devices are online
isonline = False

#Test every device, if any is online change the status to True
for (device,port) in DeviceList:
    isonline = isonline or isOpen(device,port)

#Call the functions as needed
if isonline:
    abortshutdown()
else:
    shutdown()