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node.js module to elect a master peer in a distributed system. This module uses the Bully Algorithm for the election process. Unresponsive/offline peers will be recognized through heartbeat timeouts.


Install via npm:

npm install bully

Include in your project

var Bully = require('bully');

var opts = { id: "id", /* unique identifier of this peer */
             peers: [], /* event emitter instances of other peers */
             me: me /* event emitter instance of local peer */

var bully = new Bully(opts);

bully.on("master", function () {
    console.dir('I am now the master');
bully.on("stepped_down", function () {
    console.dir('Unfortunately I had to step down from my responsibilities');

Adding a new peer

var EventEmitter = require('events').EventEmitter;

var peer = new EventEmitter(); = 'anoter_unique_id';


Remove peer


Error handling

bully.on("error", function (err) {
    // handle error here


  • Unknown Peer: triggered once a message is received from an unknown


See example.js. Run with full debug information as follows:

DEBUG=bully npm test