Node.js Express Graceful shutdown Kubernetes

pokey-graceful-express.js

require('dotenv').config()
const http = require('http')
const express = require('express')

const app = express()

// Routes
app.get('/', function (req, res, next) {
  console.log('got request')
  setTimeout(function timeoutDone () {
    console.log('sending response')
    res.sendStatus(200)
  }, 5000)
})
app.use(function (err, req, res, next) {
  console.log(err)
  res.sendStatus(500)
})

// Server
const host = process.env.HOST || 'localhost'
const port = process.env.PORT || 8080
const server = http
  .createServer(app)
  .on('close', () => console.log('closed')) // https://nodejs.org/dist/latest-v11.x/docs/api/http.html#http_event_close
  .listen(port, host, () => {
    console.log(`listening on ${host}:${port}`)
  })

// shutdown handling
function handleShutdown (thing) {
  console.log('got %s, starting shutdown', thing)
  if (!server.listening) process.exit(0)
  console.log('closing...')
  // TODO disconnect from databases like redis
  // https://nodejs.org/dist/latest-v11.x/docs/api/http.html#http_server_close_callback
  // https://nodejs.org/dist/latest-v11.x/docs/api/net.html#net_server_close_callback
  server.close(err => {
    if (err) {
      console.error(err)
      return process.exit(1)
    }
    console.log('exiting')
    process.exit(0)
  })
}

/*
 * references:
 * signals: http://man7.org/linux/man-pages/man7/signal.7.html
 * node signal events: https://nodejs.org/dist/latest-v11.x/docs/api/process.html#process_signal_events
 * kubernetes shutdown: https://cloud.google.com/blog/products/gcp/kubernetes-best-practices-terminating-with-grace
 */
process.on('SIGINT', handleShutdown)
process.on('SIGTERM', handleShutdown)
process.on('SIGHUP', handleShutdown) // pointless? debatable