Adding required modules and creating new koa application for user authentication project. Whole file is available https://github.com/AndrejGajdos/auth-flow-spa-node-react/blob/master/script/server.js

server.js

require('dotenv').config({ path: require('find-config')('.env') });
const Koa = require('koa');
const Router = require('koa-router');
const koaLogger = require('koa-logger');
const cors = require('@koa/cors');
const bodyParser = require('koa-bodyparser');
const serve = require('koa-static');
const send = require('koa-send');
const path = require('path');
const session = require('koa-session');
const redisStore = require('koa-redis');
const ratelimit = require('koa-simple-ratelimit');
const redis = require('redis');
const config = require('./serverConfig');
const includes = require('lodash/includes');

const app = new Koa();

// this last koa middleware catches any request that isn't handled by
// koa-static or koa-router, ie your index.html in your example
app.use(function* index() {
  yield send(this, '/dist/index.html');
});

// don't listen to this port if the app is required from a test script
if (!module.parent) {
  app.listen(process.env.PORT || 1337);
  console.log('app listen on port: 1337');
}