Node.js - reverse proxy

index.js

const internalIp = require('internal-ip')
const express = require('express')
const proxy = require('express-http-proxy')
const app = express()
const https = require('https')
const { readFileSync } = require('fs')
require('colors')

const isLocalIpHosting = process.argv[2] === 'local-ip-hosting'
const isHttps = process.argv[2] === 'https'

const server = isHttps ? https.createServer({
  key:  readFileSync('localhost-key.pem'),
  cert: readFileSync('localhost.pem')
}, app) : app

;(async() => {

  const host = '0.0.0.0'
  const port = 8080
  const proxyUrl = 'https://example.com/api/v1/'

  const clientIp = isLocalIpHosting ? await internalIp.v4() : 'localhost'
  const clientPort = 3000
  const clientUrl = `http://${clientIp}:${clientPort}`

  app.options('*', (req, res) => {
    res.header('Access-Control-Allow-Origin', clientUrl)
    res.header('Access-Control-Allow-Credentials', true)
    res.header('Access-Control-Allow-Methods', 'PUT, DELETE, PATCH')
    res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept, Authorization')
    res.sendStatus(200)
  })

  app.use(
    proxy(proxyUrl, {
      limit: '15mb',
      filter: (req, res) =>{
        return req.method !== 'OPTIONS'
      },
      proxyReqBodyDecorator(bodyContent, srcReq) {
        console.log(`${'[REQ]'.yellow} ${new Date().toString().gray}`)
        const { method, url, query } = srcReq
        console.log(`${method.magenta} ${url}`)
        if (Object.keys(query).length) {
          console.log(query)
        }
        if (bodyContent) {
          try {
            console.log(JSON.parse(bodyContent.toString('utf8')))
          } catch (err) {
            return bodyContent
          }
        }
        console.log('')
        return bodyContent
      },
      userResHeaderDecorator(headers, userReq, userRes, proxyReq, proxyRes) {
        headers['Access-Control-Allow-Origin'] = clientUrl
        headers['Access-Control-Allow-Credentials'] = true
        return headers;
      },
      userResDecorator(proxyRes, proxyResData, userReq, userRes) {
        const { statusCode, statusMessage } = proxyRes
        console.log(`${'[RES]'.yellow} ${new Date().toString().gray}`)
        let data = null
        try {
          data = JSON.parse(proxyResData.toString('utf8'))
        } catch (err) {
          console.log('ERROR'.red)
          console.error(err);
        }
        console.log(`${statusCode.toString().magenta} ${statusMessage.toString().blue}`);
        console.log(data)
        console.log('')
        return proxyResData
      }
    })
  )

  server.listen(port, host, () => {
    const protocol = isHttps ? 'https' : 'http'
    console.log(`listening at ${protocol}://%s:%s`, host, port)
    console.log('')
  })

})()