Track power on/off status of sonoff attached to 3d printer for Octopi PSU Control plugin

power_tracker.py

# /home/pi/power_tracker.py

#!/usr/bin/env python3
import paho.mqtt.client as mqtt

def on_message(c, userdata, msg):
  global state
  payload = msg.payload.decode('utf-8')
  if payload == 'ON' or payload == 'OFF':
    state = payload

state = 'OFF'
state_old = ''
host = 'sirius.lan'
stat_topic = 'stat/vulcan/power/POWER'
com_topic = 'cmnd/vulcan/power/POWER'
c = mqtt.Client(clean_session=True, client_id='power_tracker')
c.reinitialise()
c.message_callback_add(stat_topic, on_message)
c.connect(host)
c.subscribe(stat_topic)
c.publish(com_topic, '')

while True:
  c.loop(timeout=1)
  if state != state_old:
    print(state)
    with open ('/home/pi/power', 'w') as f:
        if state == 'ON':
            f.write('0')
        elif state == 'OFF':
            f.write('1')
  state_old = state


####################################
# Also needs:
####################################
# /home/pi/pow.sh
# run every 5 seconds by PSU Control plugin
#-----------------------------------
# #!/bin/sh
# test $(cat /home/pi/power) = 0
# exit $?
# 
####################################
# Add systemd service:
# /lib/systemd/system/power_tracker.service
#----------------------------------- 
# [Unit]
# Description=track power of 3d printer sonoff
# After=multi-user.target
# [Service]
# Type=idle
# ExecStart=/usr/bin/python3 /home/pi/power_tracker.py
# [Install]
# WantedBy=multi-user.target
#-----------------------------------
# setup commands
# sudo chmod 644 /lib/systemd/system/power_tracker.service
# sudo systemctl daemon-reload
# sudo systemctl enable power_tracker.service
# sudo reboot
# sudo systemctl status power_tracker.service
####################################