Using Firebase from AWS Lambda results in Task timed out - node.js

Question

I'm using a Lambda function to create users with Firebase Authentication and then save them at my own database.
var firebase = require('firebase-admin')
const serviceAccount = require('./firebase.json')
firebase.initializeApp({
credential: firebase.credential.cert(serviceAccount),
databaseURL: 'https://*****.firebaseio.com'
})
exports.handler = function(event, context, callback) {
const {email, password, name, ...} = event
firebase.auth().createUser({
email,
emailVerified: false,
password,
displayName: name,
disabled: false
})
.then(firebaseResult => {
const {uid} = firebaseResult
return saveUserAtDatabase({email, name, ...})
})
.then(result => {
callback(null, result)
})
}
The user is created at Firebase and at my database as well, but when I run it at AWS Lambda, it throws this error:
{"errorMessage":"2019-01-07T21:25:49.095Z c...e9 Task timed out after 6.01 seconds"}
Doesn't matter how much time I increase the timeout from the function or set higher memory, it still throws the same error.

Answer 1

I solved the problem setting context.callbackWaitsForEmptyEventLoop=false.
This is because callback waits for the event loop to be empty, which doesn't happen using firebase.auth().createUser(). There is the context.callbackWaitsForEmptyEventLoop option documented here http://docs.aws.amazon.com/lambda/latest/dg/nodejs-prog-model-context.html
When this property is set to false, Lambda freezes the container but does not clear the event loop when you call the callback.