node js server that serves static folder and makes proxy to api server

serve-prod-build.js

var proxy = require('express-http-proxy')
var express = require('express')
var app = express()

// e.g. I want to serve app from local dir on localhost:8000/app
// and use API from remote server http://myserver/api

const localAppStaticDir = '../somedir/someapp/build'
const localAppPath = '/app'
const localApiPath = '/api'
const serverApiPath = '/api'
const serverUrl = 'http://myserver'
const port = 8000

console.log('starting proxy')
app.use(localApiPath, proxy(serverUrl, {
  proxyReqOptDecorator: function(proxyReqOpts, originalReq) {
    // here can be modified the request (headers, etc.)
    // proxyReqOpts.rejectUnauthorized = false
    return proxyReqOpts
  },
  proxyReqPathResolver: function (req) {
    return serverApiPath + req.url
  },
}))
app.use(localAppPath, express.static(localAppStaticDir))

app.listen(port, '0.0.0.0')
console.log('app listening at ' + port)