index.js

var R = require ('ramda'),
    M = require ('control.monads'),
    bp = require ('body-parser'),
    fs = require ('fs'),

    express = require ('express'),

    log  = console.log,
    logI = console.logI,

    THRESHOLD_MIN = 1,

    isLessThanXMinutes = R.curry (function (x, now, machine) {
      return now - machine.time < 1000 * 60 * x;
    }),

    nil = null;
(function main (args) {
  log ("Starting...");

  var i = 0;
  var konstJson = R.curry (function (x, req, res) { res.json (x); });
  var machines = {zk: [], masters: []};

  var app = express ();

  app.use (bp.json ());

  app.post ('/soundoff', function (req, res) {
    var role = req.body.role;
    if (!role) { return res.code (400).send ("Bad Request. Need role."); }

    var masters = machines.masters;
    var zk      = machines.zk;

    var ip = req.connection.remoteAddress;
    if (R.match (/master/i, role)) { masters = R.append ({host: ip, time: Date.now ()}, masters); }
    if (R.match (/zk/i, role))     { zk      = R.append ({host: ip, time: Date.now ()}, zk); }

    machines.masters = masters;
    machines.zk = zk;

    return res.send ("");
  });

  app.get ('/masters', function (req,res) {
    machines.masters = R.filter (isLessThanXMinutes (THRESHOLD_MIN, Date.now()), machines.masters);
    res.send (machines.masters);
  });

  app.get ('/zk', function (req,res) {
    machines.zk = R.filter (isLessThanXMinutes (THRESHOLD_MIN, Date.now()), machines.zk);
    res.send (machines.zk);
  });

  app.listen (process.env.PORT || 8080);
})(process.argv);

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * This application is only supposed to be run once, behind a firewall.
 * It should never be exposed to outside traffic.
 */