node cache proxy

index.js

'use strict';
require('perish');
var Redis = require('ioredis');
var redis = new Redis();
const http = require('http');
const httpProxy = require('http-proxy');
const streamToPromise = require('stream-to-promise');

const proxy = httpProxy.createProxyServer({
  changeOrigin: true
});

const key = (req) => req.url;

proxy.on('proxyRes', (proxyRes, req) => {
  streamToPromise(proxyRes).then((data) => {
    const metadata = {
      headers: proxyRes.headers,
      statusCode: proxyRes.statusCode
    };
    const reqKey = key(req);
    redis
      .multi()
      .set(reqKey, JSON.stringify(metadata))
      .set(reqKey, data)
      .exec();
  });
});

const server = http.createServer((req, res) => {
  const reqKey = key(req);
  redis
    .pipeline()
    .get(reqKey)
    .getBuffer(`${reqKey}.data`)
    .exec()
    .then(([[, metadataStr], [, cache]]) => {
      if (cache === null) {
        proxy.web(req, res, {
          target: 'http://echo.jpillora.com/'
        });
      } else {
        const metadata = JSON.parse(metadataStr);
        Object.assign(res.headers, metadata.headers);
        res.statusCode = metadata.statusCode;
        res.write(cache);
        res.end();
      }
    });
});

server.listen(8080, () => {
  console.log('Example app listening on port 8080!');
});