Proxying with nested prefix

[yamalight]

What are you trying to achieve or the steps to reproduce?

I'm trying to create a proxy on nested prefix, e.g. /api/test.
Here's the simple example that reproduces the behavior:

// index.js
const fastify = require('fastify');
const proxy = require('fastify-http-proxy');

// setup proxy
const proxiedServer = require('./proxiedServer');

// setup app
const app = fastify();

app.get('/', (req, res) => res.send('Hello world!'));

app.register(proxy, {
  upstream: 'http://localhost:8081',
  prefix: '/api/test',
});

app.listen(8080, '0.0.0.0', (err, address) => {
  if (err) {
    console.error(err);
    return;
  }
  console.info(`Listening at ${address}`);
});

// proxiedServer.js
const fastify = require('fastify');
const app = fastify();

app.get('/', (req, res) => res.send('Hello proxied GET world!'));
app.post('/', (req, res) => res.send('Hello proxied POST world!'));

app.listen(8081, (err, address) => {
  if (err) {
    console.error(err);
    return;
  }
  console.info(`Listening at ${address}`);
});

Online test version can be found here on glitch

What was the result you received?

Trying to GET or POST to /api/test returns 404.

What did you expect?

Get correct proxied responses.

Context

• node version: 8, 10
• fastify version: 1.7.0
• fastify-http-proxy version: 0.4.0
• os: Linux, Mac
• any other relevant information:

If you change /api/test to /test - it starts working fine.

I've also tried using plugin approach and wrapping proxy in the following block:

app.register((inst, opts, next) => {
  inst.register(proxy, {
    upstream: 'http://localhost:8081',
    prefix: '/test',
  });
  next();
}, {prefix: '/api'});

This still results in 404.

[yamalight]

seems to work perfectly now. thank you!