zoff/server/app.js

var cluster = require("cluster"),
  net = require("net"),
  path = require("path"),
  //publicPath = path.join(__dirname, 'public'),
  http = require("http"),
  port = 8080,
  farmhash = require("farmhash"),
  uniqid = require("uniqid"),
  num_processes = require("os").cpus().length;

publicPath = path.join(__dirname, "public");
pathThumbnails = __dirname;

try {
  var redis = require("redis");
  var client = redis.createClient({ host: "localhost", port: 6379 });
  client.on("error", function(err) {
    console.log("Couldn't connect to redis-server, assuming non-clustered run");
    num_processes = 1;
    startSingle(false, false);
    client.quit();
  });
  client.on("connect", function() {
    startClustered(true);
    client.quit();
  });
} catch (e) {
  console.log("Couldn't connect to redis-server, assuming non-clustered run");
  num_processes = 1;
  startSingle(false, false);
}

function startClustered(redis_enabled) {
  //Found https://stackoverflow.com/questions/40885592/use-node-js-cluster-with-socket-io-chat-application
  if (cluster.isMaster) {
    var workers = [];
    var spawn = function(i) {
      workers[i] = cluster.fork();
      workers[i].on("exit", function(code, signal) {
        if (code == 1) {
          process.exit(1);
          return;
        }
        console.log("respawning worker", i);
        spawn(i);
      });
    };

    for (var i = 0; i < num_processes; i++) {
      spawn(i);
    }

    var worker_index = function(ip, len) {
      //console.log(ip);
      var s = "";
      if (ip !== undefined) {
        return farmhash.fingerprint32(ip) % len;
      }
      ip = uniqid.time();
      for (var i = 0, _len = ip.length; i < _len; i++) {
        if (!isNaN(ip[i])) {
          s += ip[i];
        }
      }
      return Number(s) % len;
    };

    var server = net
      .createServer({ pauseOnConnect: true }, function(connection, a) {
        var worker =
          workers[worker_index(connection.address().address, num_processes)];
        worker.send("sticky-session:connection", connection);
      })
      .listen(port);
  } else {
    startSingle(true, redis_enabled);
  }
}

function startSingle(clustered, redis_enabled) {
  var server;
  var client = require("./apps/client.js");
  try {
    var cert_config = require(path.join(
      path.join(__dirname, "config"),
      "cert_config.js"
    ));
    var fs = require("fs");
    var privateKey = fs.readFileSync(cert_config.privateKey).toString();
    var certificate = fs.readFileSync(cert_config.certificate).toString();
    var ca = fs.readFileSync(cert_config.ca).toString();
    var credentials = {
      key: privateKey,
      cert: certificate,
      ca: ca
    };
    var https = require("https");
    server = https.Server(credentials, routingFunction);
  } catch (err) {
    console.log("Starting without https (probably on localhost)");
    server = http.createServer(routingFunction);
  }

  if (clustered) {
    server.listen(onListen);
  } else {
    server.listen(port, onListen);
  }

  var socketIO = client.socketIO;

  if (redis_enabled) {
    var redis = require("socket.io-redis");
    try {
      socketIO.adapter(redis({ host: "localhost", port: 6379 }));
    } catch (e) {
      console.log("No redis-server to connect to..");
    }
  }
  socketIO.listen(server);

  process.on("message", function(message, connection) {
    if (message !== "sticky-session:connection") {
      return;
    }
    server.emit("connection", connection);
    connection.resume();
  });
}

function onListen() {
  console.log("Started with pid [" + process.pid + "]");
}

function routingFunction(req, res, next) {
  var client = require("./apps/client.js");
  var admin = require("./apps/admin.js");
  try {
    var url = req.headers["x-forwarded-host"]
      ? req.headers["x-forwarded-host"]
      : req.headers.host.split(":")[0];
    var subdomain = req.headers["x-forwarded-host"]
      ? req.headers["x-forwarded-host"].split(".")
      : req.headers.host.split(":")[0].split(".");

    if (subdomain.length > 1 && subdomain[0] == "admin") {
      admin(req, res, next);
    } else {
      client(req, res, next);
    }
  } catch (e) {
    console.log("Bad request for " + req.headers.host + req.url, e);
    res.statusCode = 500;
    res.write("Bad request"); //write a response to the client
    res.end(); //end the response
  }
}