turbobreaker/lib/turbobreaker.js

Exposes circuit breaker metrics through a Hystrix compliant stream

'use strict';

exports.__esModule = true;

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { 'default': obj }; }

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError('Cannot call a class as a function'); } }

var _http = require('http');

var _http2 = _interopRequireDefault(_http);

var _url = require('url');

require('es6-collections');

var HYSTRIX_STREAM_PATH = '/hystrix.stream';

var clients = new Set();
var noop = function noop() {};

var TurboBreaker = (function () {
  function TurboBreaker() {
    var config = arguments.length <= 0 || arguments[0] === undefined ? {} : arguments[0];
    var callback = arguments.length <= 1 || arguments[1] === undefined ? noop : arguments[1];

    _classCallCheck(this, TurboBreaker);

    if (typeof config === 'function') {
      callback = config;
      config = {};
    }
    this.config = config;
    this.server = this.createServer(callback);
  }

  TurboBreaker.prototype.command = function command(data) {
    clients.forEach(function (res) {
      res.write("data: " + JSON.stringify(data) + "\n\n");
    });
  };

  TurboBreaker.prototype.stop = function stop() {
    this.server.close();
  };

  TurboBreaker.prototype.createServer = function createServer(callback) {
    var server = _http2['default'].createServer(function (req, res) {
      var path = _url.parse(req.url).path;
      if (path === HYSTRIX_STREAM_PATH) {
        // Stop the connection from timing out:
        req.setTimeout(0);
        // Get the client to understand us:
        res.writeHead(200, {
          'Content-Type': 'text/event-stream',
          'Cache-Control': 'no-cache',
          'Connection': 'keep-alive'
        });

        res.write("\n");

        req.on('close', function () {
          clients['delete'](res);
        });

        clients.add(res);
      } else {
        // Reject the request:
        res.writeHead(404);
        res.end();
      }
    });
    server.listen(this.config.port || 8080, callback);
    return server;
  };

  return TurboBreaker;
})();

exports.TurboBreaker = TurboBreaker;