procfiled/proxy.js

Node.js process manager for Procfile-based applications

// Copyright IBM Corp. 2012,2016. All Rights Reserved.
// Node module: procfiled
// This file is licensed under the MIT License.
// License text available at https://opensource.org/licenses/MIT

var fs = require("fs");
var http = require("http");
var https = require("https");
var htproxy = require("http-proxy");

var port = parseInt(process.env.PORT);

var upstream_host = process.env.UPSTREAM_HOST;
var upstream_port = parseInt(process.env.UPSTREAM_PORT);
var upstream_size = parseInt(process.env.UPSTREAM_SIZE);
var sslCert = process.env.SSL_CERT;
var sslKey = process.env.SSL_KEY;
var sslPort = parseInt(process.env.SSL_PORT);

var addresses = [];
for (var i = 0; i < upstream_size; i++) {
  addresses.push({
    host: upstream_host,
    port: upstream_port + i,
    protocol: "http",
  });
}

// Proxy
var proxy = htproxy.createProxyServer({
  // Set the x-forwarded- headers, because apps often need them to make
  // decisions (such as about redirecting to SSL or a canonical host),
  // and proxies often do this for you in the real world.
  xfwd: true,
});

// Hanle Error
proxy.on("error", function (err, req, res) {
  console.error("Proxy Error: ", err);
  res.writeHead(500);
  res.write("Upstream Proxy Error");
  res.end();
});

// Main HTTP Server
http
  .createServer(function (req, res) {
    var target = addresses.shift();

    proxy.web(req, res, { target: target });

    addresses.push(target);
  })
  .listen(port, function () {
    process.send({ http: this.address().port });
  });

if (sslCert && sslKey) {
  https
    .createServer(
      {
        key: fs.readFileSync(sslKey),
        cert: fs.readFileSync(sslCert),
      },
      function (req, res) {
        var target = addresses.shift();

        proxy.web(req, res, { target: target });

        addresses.push(target);
      }
    )
    .listen(sslPort, function () {
      process.send({ https: this.address().port });
    });
}