New undici pool is created on each request

[artur-ma]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Fastify version

3.22.1

Plugin version

6.4.0

Node.js version

16.11

Operating system

macOS

Operating system version (i.e. 20.04, 11.3, 10)

11.3

Description

proxy will create a new connection pool on each request, which will produce unlimited number of connections to single host and high resource usage (also performance decrease)

https://github.com/fastify/fastify-reply-from/blob/master/lib/request.js#L133

Steps to Reproduce

create proxy:

const app = require('fastify')({
  logger: true
});

app.register(require('fastify-reply-from'), {
  base: 'http://localhost:3010/',
  undici: {
    connections: 10,
  },
})

app.get('/alive', (request, reply) => {
  reply.from('/alive')
})

app.listen(3000, (err) => {
  if (err) {
    throw err
  }
})

create target

const fastify = require('fastify')({
  logger: true,
  keepAliveTimeout: 30000,
})

fastify.get('/alive', (request, reply) => {
  reply.send({ hello: 'world' })
})

// Run the server!
fastify.listen(3010, (err, address) => {
  if (err) throw err
  // Server is now listening on ${address}
})

run autocannon -r 20 http://localhost:3000/alive -f

then check number of file descriptors (open sockets) both on target and proxy
lsof -a -p <PID> | wc -l

Expected Behavior

Since number of connections is limited to 10 per origin (host), expected limited number of file descriptors(open sockets), but the number continue to grow to thousands

fastify-reply-from should use build-in request function implemented in undici
it uses Agent singleton with a single pool per host

p.s with plugin 5.x it works as expected

[mcollina]

This is a bad bug I should have spotted. Could you send a PR? It'd probably take less time as I'm swamped.

[artur-ma]

Thanks for the fast fix! Soryy for not sending the PR, I fell to sleep :D

[climba03003]

Thanks for the fast fix! Soryy for not sending the PR, I fell to sleep :D

Can you double check is the solution works on your end?

[artur-ma]

@climba03003 yes, it behaves as expected, today we will deploy it, then I will finally confirm it
Thanks!

[artur-ma]

looks way better