Structuring the Firebase Cloud functions and triggers to scale

index.js

const functions = require('firebase-functions');
const admin = require('firebase-admin');
const glob = require('glob');

admin.initializeApp(functions.config().firebase);

/**
 * Cloud triggers
 */
const files = glob.sync('./triggers/**/*.f.js', {cwd: __dirname});
for (let f=0, fl=files.length; f<fl; f++) {
    const file = files[f];
    const splits = file.slice(0, -5).split('/');
    const functionName = splits[splits.length - 1];
    exports[functionName] = require(file);
}

/**
 * Cloud http function calls
 */
const httpFiles = glob.sync('./http_functions/**/*.f.js', {cwd: __dirname});
for (let f=0, fl=httpFiles.length; f<fl; f++) {
    const file = httpFiles[f];
    const splits = file.slice(0, -5).split('/');
    const funName = splits[splits.length - 1];
    exports[funName] = require(file);
}

onUserSignIn.f.js

/**
 * File located at triggers/db/onUserSignIn.f.js
 */
const functions = require('firebase-functions');
const admin = require('firebase-admin');

exports = module.exports = functions.database.ref(...)
.onUpdate((_, context)=>{
    var message = {...};
    return admin.messaging().send(message)
        .then((response)=>{
            console.log("Notification sent!");
        })
        .catch((err)=>{
            console.log("Error sending notification for signin", err);
        });
});