external-server.js

const net = require("net");
const fs = require("fs");

const bundlePath = "./var/webpack/";
const bundleFileName = "server-bundle.js";
const unixSocketPath = "var/node.sock";

let currentArg;

class Handler {
  constructor() {
    this.queue = [];
    this.initialized = false;
  }

  handle(connection) {
    const callback = () => {
      connection.setEncoding("utf8");
      let data = [];
      let lastChar;
      connection.on("data", chunk => {
        data.push(chunk);
        lastChar = chunk.substr(chunk.length - 1);

        if (lastChar === "\0") {
          data = data.join("");
          let result = eval(data.slice(0, -1));
          connection.write(result);
          console.log("Request processed");
          connection.end();
        }
      });
    };
    if (this.initialized) {
      callback();
    } else {
      this.queue.push(callback);
    }
  }

  initialize() {
    console.log("Processing " + this.queue.length + " pending requests");
    var callback = this.queue.pop();
    while (callback) {
      callback();
      callback = this.queue.pop();
    }

    this.initialized = true;
  }
}

var handler = new Handler();

process.argv.forEach(val => {
  if (val[0] == "-") {
    currentArg = val.slice(1);
    return;
  }

  if (currentArg == "s") {
    bundleFileName = val;
  }
});

try {
  fs.mkdirSync(bundlePath);
} catch (e) {
  if (e.code != "EEXIST") throw e;
}

require(bundlePath + bundleFileName);
console.log("Loaded server bundle: " + bundlePath + bundleFileName);
handler.initialize();

fs.watchFile(bundlePath + bundleFileName, curr => {
  if (curr && curr.blocks && curr.blocks > 0) {
    if (handler.initialized) {
      console.log(
        "Reloading server bundle must be implemented by restarting the node process!"
      );
      return;
    }

    require(bundlePath + bundleFileName);
    console.log("Loaded server bundle: " + bundlePath + bundleFileName);
    handler.initialize();
  }
});

fs.stat(unixSocketPath, function(err) {
  if (!err) {
    fs.unlinkSync(unixSocketPath);
  }
  var unixServer = net.createServer(function(connection) {
    handler.handle(connection);
  });

  unixServer.listen(unixSocketPath);

  process.on("SIGINT", () => {
    unixServer.close();
    process.exit();
  });
});