slimp/node_modules/undici/docs/best-practices/proxy.md

Connecting through a proxy

Connecting through a proxy is possible by:

• Using AgentProxy.
• Configuring Client or Pool constructor.

The proxy url should be passed to the Client or Pool constructor, while the upstream server url should be added to every request call in the path. For instance, if you need to send a request to the /hello route of your upstream server, the path should be path: 'http://upstream.server:port/hello?foo=bar'.

If you proxy requires basic authentication, you can send it via the proxy-authorization header.

Connect without authentication

import { Client } from 'undici'
import { createServer } from 'http'
import proxy from 'proxy'

const server = await buildServer()
const proxyServer = await buildProxy()

const serverUrl = `http://localhost:${server.address().port}`
const proxyUrl = `http://localhost:${proxyServer.address().port}`

server.on('request', (req, res) => {
  console.log(req.url) // '/hello?foo=bar'
  res.setHeader('content-type', 'application/json')
  res.end(JSON.stringify({ hello: 'world' }))
})

const client = new Client(proxyUrl)

const response = await client.request({
  method: 'GET',
  path: serverUrl + '/hello?foo=bar'
})

response.body.setEncoding('utf8')
let data = ''
for await (const chunk of response.body) {
  data += chunk
}
console.log(response.statusCode) // 200
console.log(JSON.parse(data)) // { hello: 'world' }

server.close()
proxyServer.close()
client.close()

function buildServer () {
  return new Promise((resolve, reject) => {
    const server = createServer()
    server.listen(0, () => resolve(server))
  })
}

function buildProxy () {
  return new Promise((resolve, reject) => {
    const server = proxy(createServer())
    server.listen(0, () => resolve(server))
  })
}

Connect with authentication

import { Client } from 'undici'
import { createServer } from 'http'
import proxy from 'proxy'

const server = await buildServer()
const proxyServer = await buildProxy()

const serverUrl = `http://localhost:${server.address().port}`
const proxyUrl = `http://localhost:${proxyServer.address().port}`

proxyServer.authenticate = function (req, fn) {
  fn(null, req.headers['proxy-authorization'] === `Basic ${Buffer.from('user:pass').toString('base64')}`)
}

server.on('request', (req, res) => {
  console.log(req.url) // '/hello?foo=bar'
  res.setHeader('content-type', 'application/json')
  res.end(JSON.stringify({ hello: 'world' }))
})

const client = new Client(proxyUrl)

const response = await client.request({
  method: 'GET',
  path: serverUrl + '/hello?foo=bar',
  headers: {
    'proxy-authorization': `Basic ${Buffer.from('user:pass').toString('base64')}`
  }
})

response.body.setEncoding('utf8')
let data = ''
for await (const chunk of response.body) {
  data += chunk
}
console.log(response.statusCode) // 200
console.log(JSON.parse(data)) // { hello: 'world' }

server.close()
proxyServer.close()
client.close()

function buildServer () {
  return new Promise((resolve, reject) => {
    const server = createServer()
    server.listen(0, () => resolve(server))
  })
}

function buildProxy () {
  return new Promise((resolve, reject) => {
    const server = proxy(createServer())
    server.listen(0, () => resolve(server))
  })
}