puppeteer_proxy_per_page_router.js

const puppeteer = require('puppeteer');
const ProxyChain = require('proxy-chain');

const ROUTER_PROXY = 'http://127.0.0.1:8000';

const uas = [
  'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.139 Safari/537.36',
  'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36',
];


// Needs to be set prior to puppeteer.launch()
const defaultUa =
  'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3312.0 Safari/537.36';

const proxies = ['http://127.0.0.1:24000', 'http://127.0.0.1:24001', 'http://127.0.0.1:24003'];

(async () => {
  const browser = await puppeteer.launch({
    headless: false,
    args: [
      '--no-sandbox',
      `--proxy-server=${ROUTER_PROXY}`,
      `--user-agent=${defaultUa} `,
    ],
  });
  const page1 = await browser.newPage();
  const page2 = await browser.newPage();

  try {
    await page1.setUserAgent(uas[0]);
    await page1.goto('http://www.whatsmyip.org/');
  } catch (e) {
    console.log(e);
  }

  try {
    await page2.setUserAgent(uas[1]);
    await page2.goto('http://www.whatsmyip.org/');
  } catch (e) {
    console.log(e);
  }

  await browser.close();
})();

const server = new ProxyChain.Server({
  // Port where the server the server will listen. By default 8000.
  port: 8000,

  // Enables verbose logging
  verbose: false,

  prepareRequestFunction: ({
    request,
    username,
    password,
    hostname,
    port,
    isHttp,
  }) => {
    let upstreamProxyUrl;

    if (request.headers['user-agent'] === uas[0]) upstreamProxyUrl = proxies[0];
    if (request.headers['user-agent'] === uas[1]) upstreamProxyUrl = proxies[1];
    
    // some requests are sent from browser
    // (headless=false & incognito=false)
    if (request.headers['user-agent'] === defaultUa) upstreamProxyUrl = proxies[2];

    return { upstreamProxyUrl };
  },
});

server.listen(() => {
  console.log(`Router Proxy server is listening on port ${8000}`);
});