Telegram bot to monitor temperatures. Created to itch my scratch of wanting to monitor the temperature of a brewing vessel using ESP8266/DS18B20 and a mosquitto broker. Temperatures are logged using RRDTOOL and recorded every 10 seconds.

monitor_fermentation.py

import __main__
import os
import tempfile

import paho.mqtt.client as mqtt
import rrdtool
import telegram
import telegram.ext


TOKEN_ID = '<your bot id>'
MQTT_SERVER = '<your mqtt server>'

# temperature read from the sensor and shared between the telegram thread and
# the main thread. This is a read only variable and I don't really need
# precision here, so I'm not even worrying about protecting any concurrent
# access. That's how I roll.
temp = 85


# -- telegram section
updater = telegram.ext.Updater(token=TOKEN_ID)
dispatcher = updater.dispatcher

def on_beertemp(bot, update):
    # global variables!
    global temp
    bot.send_message(chat_id=update.message.chat_id, text=temp)

def beer_rrd():
    return os.path.join(os.path.dirname(__main__.__file__), 'beer.rrd')

def on_beertempchart(bot, update):
    # call rrdtool to generate a chart
    fd, fname = tempfile.mkstemp('.png')
    rrdtool.graph(
        fname,
        '-w', '800',
        '-h', '300',
        '-a', 'PNG',
        '--start', '-{0}'.format(6*5*60*24),
        '--end', 'now',
        'DEF:temp1={0}:temp1:MAX'.format(beer_rrd()),
        'LINE1:temp1#ff0000:"cerveza"'
    )

    try:
        with open(fname) as f:
            bot.send_photo(chat_id=update.message.chat_id, photo=f)
    finally:
        os.unlink(fname)

# register /beer and /chart command handlers
beertemp_handler = telegram.ext.CommandHandler('beer', on_beertemp)
dispatcher.add_handler(beertemp_handler)
beertempchart_handler = telegram.ext.CommandHandler('chart', on_beertempchart)
dispatcher.add_handler(beertempchart_handler)
updater.start_polling()

# -- paho MQTT section
# The callback for when the client receives a CONNACK response from the server.
def on_connect(client, userdata, flags, rc):
    print("Connected with result code "+str(rc))

    # Subscribing in on_connect() means that if we lose the connection and
    # reconnect then subscriptions will be renewed.
    client.subscribe("/topic/temp1")

# The callback for when a PUBLISH message is received from the server.
def on_message(client, userdata, msg):
    global temp
    temp = float(msg.payload)
    # call rrd tool to update chart
    rrdtool.update(beer_rrd(), 'N:{0}'.format(temp))

client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message

client.connect(MQTT_SERVER, 1883, 60)

# Blocking call that processes network traffic, dispatches callbacks and
# handles reconnecting.
# Other loop*() functions are available that give a threaded interface and a
# manual interface.
client.loop_forever()