MQTT Generator Script

README.rst

MQTT Generator

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

Usage

Download mqttgen.py 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 mqttgen.py config.json

Configuration

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.

Author

Mariano Guerra from Event Fabric

License

Public Domain

config.json

{
    "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"
        }
    }
}

mqttgen.py

#!/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)
        time.sleep(interval_secs)


def main(config_path):
    """main entry point, load and validate config and call generate"""
    try:
        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")
                return

            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:
        main(sys.argv[1])
    else:
        print("usage %s config.json" % sys.argv[0])