How do I generate custom response when proxy error in http-proxy-middleware

Question

TLDR: how do I customize the "Error occurred while trying to proxy: localhost:3000/" in http-proxy-middleware ?

I'm using the node package http-proxy-middleware as a proxy.

I have some patterns where I know that the proxying will fail. Here is a minimal example of what happens:

const { createProxyMiddleware } = require('http-proxy-middleware');

require('express')().use(
  '/',
  createProxyMiddleware({
    target: 'http://failhtis/'
  })
).listen(3000);

This will display this in my browser:

And in my console:

[HPM] Error occurred while proxying request localhost:3000/ to http://failhtis/ [ENOTFOUND] (https://nodejs.org/api/errors.html#errors_common_system_errors)

What I would love to do is generate a custom message / html for the error. How do I manage that?

I've tried the ejectPlugin method described here: https://github.com/chimurai/http-proxy-middleware#ejectplugins-boolean-default-false but without success.

To sum up: I know error will happen in my setup, how do I send a custom answer instead of the "Error occured while proxying..." message?

Answer 1

I just found the answer to my question.

Here it is for v2

const { createProxyMiddleware } = require('http-proxy-middleware');

console.log(Options)

require('express')().use(
  '/',
  createProxyMiddleware({
    target: 'http://sc_rstudio/',
    changeOrigin: true,
    logLevel: 'debug',
    onError: (err, req, res) => {
      console.log("pouet")
      res.send('<h1>Something went wrong.</h1>');
    },
  })
).listen(3000);