var admin = require('firebase-admin');
// Fetch the service account key JSON file contents
var serviceAccount = require('path/to/serviceAccountKey.json');
// Initialize the app with a service account, granting admin privileges
credential: admin.credential.cert(serviceAccount),
databaseURL: 'https://databaseName.firebaseio.com',
// As an admin, the app has access to read and write all data, regardless of Security Rules
var db = admin.database();
var ref = db.ref('restricted_access/secret_document');
ref.once('value', function(snapshot) {
console.log(snapshot.val());