This is late, but in case someone else is looking:
Zipping your project folder instead of the contents of the project folder can cause this. The zipped folder, when extracted, should not contain a folder with the lambda files in it, but should have the index.js file and the node_modules folder at root level.
A working example of a lambda function is (using latest shiny firebase stuff *sigh*):
var firebase = require('firebase');
// Your service account details
var credentials = {
"type": "service_account",
"project_id": "project-123451234512345123",
"private_key_id": "my1private2key3id",
"private_key": "-----BEGIN PRIVATE KEY-----InsertKeyHere-----END PRIVATE KEY-----\n",
"client_email": "projectname@project-123451234512345123.iam.gserviceaccount.com",
"client_id": "1111222223333344444",
"auth_uri": "https://accounts.google.com/o/oauth2/auth",
"token_uri": "https://accounts.google.com/o/oauth2/token",
"auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
"client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/projectname%40project-123451234512345123.iam.gserviceaccount.com"
};
firebase.initializeApp({
serviceAccount: credentials,
databaseURL: "https://project-123451234512345123.firebaseio.com"
});
exports.handler = function (event, context, callback) {
// I use some data passed in from AWS API Gateway:
if (!event.firebaseUid) {
callback('Missing param for id');
}
firebase.database().ref().child('users').child(firebaseUid).child('at').set(newTokens.access_token).then(function (data) {
console.log('Firebase data: ', data);
firebase.database().goOffline();
callback(null, 'Firebase data: ', data);
}).catch(function (error) {
callback('Database set error ' + error);
});
};
Now for the caveat. I have experienced this causing the lambda function to timeout even after the firebase callback has happened, ie. the set function seems to create a listener that holds the lambda function open despite return of correct data.
Update: Calling firebase.database().goOffline() fixes the Lambda function timeout issue i was experiencing.
The usual cautions about security not being verified or appropriate, and the possibilities of halting space and time by using this apply.