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MQTT Generator Script

MQTT Generator

A simple python 3 script to generate sensor data from a config file and send it to an MQTT broker.


Download and config.json files (click on the Raw button at the top right and then save the content), edit config.json to fit your needs, if you are using it to run the Event Fabric sensors dashboard then don't change the topic in config.json unless you want to change it in the dashboard too.

The script uses the python paho-mqtt library you can install it with something like sudo pip3 install paho-mqtt.

python3 config.json


Edit config.json, you can add as many sensors in the "sensors" object as you wish.

Change the values in "mqtt" section to match your MQTT broker settings.

  • password is optional if you don't need password
  • if username is missing, no authentication will be used.


Mariano Guerra from Event Fabric


Public Domain

"mqtt": {
"username": "mariano",
"password": "secret",
"host": "localhost",
"port": 1883,
"topic": "sensors"
"misc": {
"interval_ms": 1000,
"verbose": true
"sensors": {
"Sensor 1": {
"lat": 10,
"lng": 10,
"unit": "C",
"type": "temperature",
"range": [0, 45],
"description": "Main Entrance"
"Sensor 2": {
"lat": 90,
"lng": 90,
"unit": "C",
"type": "temperature",
"range": [0, 45],
"description": "Kitchen"
"Sensor 3": {
"lat": 90,
"lng": 10,
"unit": "C",
"type": "temperature",
"range": [0, 45],
"description": "Deposit"
"Sensor 4": {
"lat": 10,
"lng": 90,
"unit": "C",
"type": "temperature",
"range": [0, 45],
"description": "Assemlby Floor"
"Sensor 5": {
"lat": 50,
"lng": 50,
"unit": "C",
"type": "temperature",
"range": [0, 45],
"description": "Offices"
#!/usr/bin/env python3
"""a simple sensor data generator that sends to an MQTT broker via paho"""
import sys
import json
import time
import random
import paho.mqtt.client as mqtt
def generate(host, port, username, password, topic, sensors, interval_ms, verbose):
"""generate data and send it to an MQTT broker"""
mqttc = mqtt.Client()
if username:
mqttc.username_pw_set(username, password)
mqttc.connect(host, port)
keys = list(sensors.keys())
interval_secs = interval_ms / 1000.0
while True:
sensor_id = random.choice(keys)
sensor = sensors[sensor_id]
min_val, max_val = sensor.get("range", [0, 100])
val = random.randint(min_val, max_val)
data = {
"id": sensor_id,
"value": val
for key in ["lat", "lng", "unit", "type", "description"]:
value = sensor.get(key)
if value is not None:
data[key] = value
payload = json.dumps(data)
if verbose:
print("%s: %s" % (topic, payload))
mqttc.publish(topic, payload)
def main(config_path):
"""main entry point, load and validate config and call generate"""
with open(config_path) as handle:
config = json.load(handle)
mqtt_config = config.get("mqtt", {})
misc_config = config.get("misc", {})
sensors = config.get("sensors")
interval_ms = misc_config.get("interval_ms", 500)
verbose = misc_config.get("verbose", False)
if not sensors:
print("no sensors specified in config, nothing to do")
host = mqtt_config.get("host", "localhost")
port = mqtt_config.get("port", 1883)
username = mqtt_config.get("username")
password = mqtt_config.get("password")
topic = mqtt_config.get("topic", "mqttgen")
generate(host, port, username, password, topic, sensors, interval_ms, verbose)
except IOError as error:
print("Error opening config file '%s'" % config_path, error)
if __name__ == '__main__':
if len(sys.argv) == 2:
print("usage %s config.json" % sys.argv[0])
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ajcs3 commented Feb 23, 2017

I dont have any user and password for the connection. Instead what I have is KS and TS certificates. Could you please help us how this can be used with in your framework.


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LimeBlast commented Mar 11, 2017

Thank you for this, it gave me the inspiration to write my own generating script (I had far simpler requirements than you).


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ApostolosLL commented Aug 30, 2018

Thank you, that saved me a lot of time!
However, when I ran the script, I noticed that after ~20 messages the client disconnected (or at least the sent messages never arrived at the broker).
Inserting an mqttc.loop_start() after the mqttc.connect(host, port) fixed that issue.


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LouKingFr commented Apr 12, 2021

hello can u explain me more how it works , when i run it i just got a 0 , how can i send a message or a simply data like temperature to a broker for example .


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