index.js

'use strict';
const mqtt = require('mqtt'),
	url = require('url'),
	Topics = require('./subscriptions/topics-aggregator.js');



const topics = Topics.getTopicsToBeSubscribed(),
	mqtt_url = url.parse(process.env.CLOUDMQTT_URL || 'mqtt://localhost:1883'),
	auth = (mqtt_url.auth || ':').split(':'),
	mqtt_broker_url = `mqtts://${mqtt_url.host}`;

const options  = {
	port: mqtt_url.port,
	clientId: `mqttjs_${
		Math
			.random()
			.toString(16)
			.substr(2, 8)
		}`,
	username: auth[0],
	password: auth[1]
};

const client = mqtt.connect(mqtt_broker_url, options);

client.on('connect', () => {
	//subscribe to the aggregated topics
	for (let topic in topics) {
		client.subscribe(topic);
		console.log(`subscribed to ${topic}`);
	}
	client.publish('/all', 'mqtt-processor is up.');
});


client.on('message', (topicName, message) => {
	//call respective callbacks
	topics[topicName](message);
});

client.on('error', (err) => {
	console.error(err);
});