Make ProxyAgent take another Agent as an option

[mcollina]

In

undici/lib/proxy-agent.js

Line 41 in 0beedf9

this[kAgent] = new Agent(opts)

, we create a new Agent for every ProxyAgent. I think we should make ProxyAgent take an instance of Agent as an option, making something like the following possible:

import { ProxyAgent, request, setGlobalDispatcher } from "undici"
import { CookieAgent } from "http-cookie-agent/undici"
import { CookieJar } from "tough-cookie"


async function test() {
  const proxyAgent = new ProxyAgent("http://127.0.0.1:10810")
  setGlobalDispatcher(proxyAgent)
  const jar = new CookieJar()
  const agent = new CookieAgent({ cookies: { jar } })
  await request("https://test.com", {
    dispatcher: agent,
  })
}

Help would be greatly appreciated! 🙏

Originally posted by @tgioer in #1957

[RishabhKodes]

Hey @mcollina, I'm taking up this issue.

[jabali2004]

Hey @mcollina 👋🏼
Can we close that one? Since #2003 has been merged.