on event of firebase is not working with AWS lambda - node.js

Question

In the following event .once event is working fine
'use strict';
let firebase = require('firebase');
exports.handler = function(event, context)
{
context.callbackWaitsForEmptyEventLoop = false;
firebase.initializeApp({
serviceAccount: {},
databaseURL: "https://harmanconnectedcar-180411.firebaseio.com/"
});
firebase.database().ref('events').once('value').then(function(snapshot) {
console.log("*************event**********************")
console.log (snapshot.val()) ;
context.succeed() ;
});
var starCountRef = firebase.database().ref('events' );
starCountRef.on('value', function(snapshot) {
console.log("*************snapshot*****snapshot*****************")
console.log (snapshot.val()) ;
context.succeed();
})
}
When i try starCountRef.on i am not able to see the logs printed
Once i put the lambda function in AWS and write to firebase from firebase console i am not able to see the events where do i need to see the logs how to check starCountRef.on event(i mean the real time logs)

Answer 1

You're starting two asynchronous listeners. Then when the first of them finishes you call context.succeed(). At that point Lambda terminates your function, so the second listener never completes.
To makes this code work, you need to ensure you only call context.succeed() when all of the data has loaded. An easy way to do this is by using Promise.all():
exports.handler = function(event, context)
{
context.callbackWaitsForEmptyEventLoop = false;
firebase.initializeApp({
serviceAccount: {},
databaseURL: "https://harmanconnectedcar-180411.firebaseio.com/"
});
var starCountRef = firebase.database().ref('events' );
var promises = [];
promises.push(firebase.database().ref('events').once('value'));
promises.push(starCountRef.once('value');
Promises.all(promises).then(function(snapshots) {
snapshot.forEach(function(snapshot) {
console.log(snapshot.val();
});
context.succeed();
});
}

Answer 2

You seem to be mixing up two technologies here.
The onWrite method is an construct of Cloud Functions for Firebase, which (as far as I know) cannot be deployed on Amazon lambda.
If you want to access your Firebase Realtime Database from Amazon Lambda, you can use the Firebase Admin SDK. But that doesn't include a way to trigger your code whenever the database is written.