Start a new expressjs https web server, using a valid certificate or a new auto generated self signed one and handle SIGINT to exit gracefully

https_srv.js

//
// To test this:
//    1) npm install express fs https pem
//    2) node https_srv.js
//    3) open a new webpage on http://127.0.0.1
//

// Provide here a valid key file and crt file to run a valid https server
// Invalid path will force the app to generate a self signed certificate
let certsFiles = {
  key: './127.0.0.1.key',
  crt: './127.0.0.1.cert'
};
// Ports numbers
const HTTP_PORT = 80;
const HTTPS_PORT = 443;

// Dependancies
let fs = require('fs');
let http = require('http');
let https = require('https');
let pem = require('pem');
let express = require('express');
let app = express();
let httpServer = http.createServer(app);
let httpsServer = null;
let privateKey = null;
let certificate = null;

// Error handling
process.on('uncaughtException', function (err) {
  if (err && (typeof err.errno !== 'undefined') && (err.errno === 'EADDRINUSE') && (isNaN(err.port) === false)) {
    console.error('Cannot start server on port ' + err.port + ', port is already in use.');
  } else {
    console.error(err);
    console.log('\n\n');
    console.log('Error detected, exiting the app...');
    process.exit(1);
  }
});

//
// your express configuration here
//

//
// Test if a valid certificate has been provided
// or generate a self signed one
//
if (fs.existsSync(certsFiles.key)) {
  privateKey = fs.readFileSync(certsFiles.key, 'utf8');
}
if (fs.existsSync(certsFiles.crt)) {
  certificate = fs.readFileSync(certsFiles.crt, 'utf8');
}
// Valid certificate: start an https server
if ((privateKey !== null) && (certificate !== null)) {
  console.log('Valid certificate provided, starting the https server.');
  httpsServer = https.createServer({ key: privateKey, cert: certificate }, app).listen(HTTPS_PORT, function (err) {
    if (err) throw err;
    else console.log('Server HTTPS started on port ' + HTTPS_PORT);
  });
} else {
  // Generate a self signed certificate
  // Will be SHA 256 + RSA 2048
  console.log('No valid certificate provided, creating a self-signed certificate...');
  pem.createCertificate({ days: 365, selfSigned: true }, function (err, keys) {
    if (err) {
      console.error('Cannot create a self-signed certificate.');
      throw err;
    }

    httpsServer = https.createServer({ key: keys.serviceKey, cert: keys.certificate }, app).listen(HTTPS_PORT, function (err) {
      if (err) throw err;
      else console.log('Server HTTPS started on port ' + HTTPS_PORT);
    });
  });
}
// Redirect all HTTP to HTTPS
httpServer.listen(HTTP_PORT, function (err) {
  if (err) throw err;
  else console.log('Server HTTP (used to redirect to HTTPS) started on port ' + HTTP_PORT);
});

app.all('*', function (req, res, next) {
  if (req.secure) {
    return next();
  }
  if (HTTPS_PORT !== 443) res.redirect('https://' + req.hostname + ':' + HTTPS_PORT + req.url);
  else res.redirect('https://' + req.hostname + req.url);
});

// Handle ^C
process.on('SIGINT', shutdown);
process.on('SIGHUP', shutdown);
process.on('SIGQUIT', shutdown);
process.on('SIGABRT', shutdown);
process.on('SIGTERM', shutdown);

// Do graceful shutdown
function shutdown () {
  httpServer.close(function () {
    console.log('Http server closed.');
  });
  httpsServer.close(function () {
    console.log('Https server closed.');
  });
}

//
// App
//
app.get('/', function (req, res) {
  res.send('This is an https page!');
});