AWSIoTButtonPOSTtoFirebase.js

'use strict';

/**
 * This is a sample AWS Lambda instance with NodeJS 
 * Simply sending a POST request to Google Firebase
 */

const AWS = require('aws-sdk');

/**
 * handler is the entry point of the button click
 */
exports.handler = (event, context, callback) => {
    console.log('Received event:', event.clickType);
    
    var request = require('request');
    
    // Firebase auth key
    var serverKey = "Firebase Server Key";
    var clientToken= "Client Device Token";

    var options = {
      url: 'https://fcm.googleapis.com/fcm/send',
      headers: {
        'Authorization': 'key=' + serverKey
      },
      json: {
        "to": clientToken,
        "data": {
            deviceId: `${event.serialNumber}`,
            deviceName: 'IoT Button',
            eventName: 'Click',
            value: `${event.clickType}, ${event.batteryVoltage}`
        }
      }
    };

    request.post(options, function optionalCallback(err, httpResponse, body) {
      if (err) {
        return callback(err);
      }
    });

};