app.js

const bodyParser = require('body-parser');
const cluster = require('cluster');
const cookieParser = require('cookie-parser');
const dotenv = require('dotenv');
const express = require('express');
const http = require('http');
const mongoose = require('mongoose');
const path = require('path');
const session = require('express-session');

const MongoStore = require('connect-mongo');

const numCPUs = process.env.WEB_CONCURRENCY || require('os').cpus().length;

if (cluster.isMaster) {
  console.log(`Master ${process.pid} is running`);

  for (let i = 0; i < numCPUs; i++)
    cluster.fork();

  cluster.on('exit', (worker, code, signal) => {
    console.log(`worker ${worker.process.pid} died`);
    cluster.fork();
  });
} else {
  const app = express();
  const server = http.createServer(app);

  dotenv.config({ path: path.join(__dirname, '.env') });

  const PORT = process.env.PORT || 3000;
  const MONGODB_URI = process.env.MONGODB_URI || 'mongodb://127.0.0.1:27017/usersmagic';

  const adRouteController = require('./routes/adRoute');
  const analyticsRouteController = require('./routes/analyticsRoute');
  const answerRouteController = require('./routes/answerRoute');
  const dataRouteController = require('./routes/dataRoute');
  const personRouteController = require('./routes/personRoute');
  const questionRouteController = require('./routes/questionRoute');

  mongoose.connect(MONGODB_URI, {
    useNewUrlParser: true,
    useUnifiedTopology: true
  });

  app.use(express.static(path.join(__dirname, 'public')));
  app.use(bodyParser.urlencoded({ extended: false }));
  app.use(bodyParser.json());

  const sessionOptions = session({
    secret: process.env.SESSION_SECRET,
    resave: false,
    saveUninitialized: false,
    store: MongoStore.create({
        mongoUrl: MONGODB_URI
    })
  });

  app.use(sessionOptions);
  app.use(cookieParser());

  app.use((req, res, next) => {
    res.append('Access-Control-Allow-Origin', ['*']);
    res.append('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE');
    res.append('Access-Control-Allow-Headers', 'Content-Type');
    
    if (!req.query || typeof req.query != 'object')
      req.query = {};
    if (!req.body || typeof req.body != 'object')
      req.body = {};
    next();
  });

  app.use('/ad', adRouteController);
  app.use('/analytics', analyticsRouteController);
  app.use('/answer', answerRouteController);
  app.use('/data', dataRouteController);
  app.use('/person', personRouteController);
  app.use('/question', questionRouteController);

  server.listen(PORT, () => {
    console.log(`Server is on port ${PORT} as Worker ${cluster.worker.id} running @ process ${cluster.worker.process.pid}`);
  });
}