servers.js

const http = require('http')

const firstServer = http.createServer((req, res) => {
  console.log('firstServer request', req.url, req.headers)
  res.setHeader('set-cookie', 'foo=bar; max-age=10000000; host=localhost:8080; SameSite=Strict')
  res.setHeader('content-type', 'text/html')

  res.write('<pre>')
  res.write(JSON.stringify(req.headers, null, 2) + '\n</pre>')

  if (req.headers.cookie)
    res.end('<a href="' + secondServerHost + req.url +
            '">dont click, copy this url to the address bar, '+
            'observe cookie vanish</a>\n')
  else
    res.end('<a href="' + req.url +
            '">refresh to see cookie appear</a>\n')
})

const secondServer = http.createServer((req, res) => {
  console.log('secondServer request', req.url, req.headers)
  res.statusCode = 301
  const redir = firstServerHost + req.url
  res.setHeader('content-type', 'text/html')
  res.setHeader('location', redir)
  res.end('<a href="' + redir + '">' + redir + '</a>\n')
})

const firstServerHost = 'http://localhost:8080'
const secondServerHost = 'http://127.0.0.1:8081'

firstServer.listen(8080, _ => {
  secondServer.listen(8081, _=> {
    console.log('load in chrome: ' + firstServerHost + '/test')
  })
})