service-router/index.js

router to bounce requests to either api or web servers

/**
 * Manages the all the various servers that make up the docparse
 * infastructor. When a new api server spins up, it connects to this seaport
 * instance on the port specificed by "seaport_list_port" in config.js. Then
 * when a new api request comes in, this module can bounce it to any server in a
 * round-robin fashion
 *
 * A possible future optimization would be to put in additional routing logic to
 * bouncy to better utilize server resources. Right now we just pick a server at random
 *
 * @Author Noah Isaacson
 */
var inspect = require('eyespect').inspector();
var seaport = require('seaport');
var performBounce = require('./lib/performBounce');
var serviceDown = require('./lib/serviceDown');
var bouncy = require('bouncy');
var url = require('url');
module.exports = function(config) {
  var seaport_port = config.get('seaport:port');
  inspect(seaport_port, 'seaport listening on port')
  var server = seaport.createServer();
  server.listen(seaport_port);
  var apiOnline = false;
  var webOnline = false;

  server.on('register', function (service) {
    var role = service.role;
    if (role === 'web') {
      webOnline = true;
    }
    if (role === 'api') {
      apiOnline = true;
    }
    if (apiOnline && webOnline) {
      if (process.send) {
        process.send('listening');
        return;
      }
    }
  });

  // Bounce Requests to the appropiate server

  var bouncy_port = config.get('application:port');

  bouncy(function(req, res, bounce) {
    var parts = url.parse(req.url);
    var urlPath = parts.path
    var service = 'web';
    var apiPattern = /^\/api/;

    if (apiPattern.test(urlPath)) {
      service =  'api'
    }

    var servicePattern = /^\/static/;
    if (servicePattern.test(urlPath)) {
      service =  'static'
    }

    var ps = server.query(service);
    // inspect({service: service, req_headers: req.headers}, 'bouncing for service');
    // no servers available for the given service
    if (ps.length === 0) {
      inspect(service, 'no servers available');
      return serviceDown(req, res, bounce, service);
    }

    inspect(urlPath, 'bouncing to service: ' + service + ' for url')
    // bounce api request to a random server registered with seaport
    var serverIndex = ps[Math.floor(Math.random()*ps.length)];
    inspect(serverIndex, 'bouncing now')
    var host = serverIndex.host;
    var port = serverIndex.port;

    inspect(host,'host')
    inspect(port,'port')
    bounce(host, port)
  }).listen(bouncy_port)

  inspect(bouncy_port, 'application listening on port');
  return server;
}