add_cname.js

var AWS = require('aws-sdk');

AWS.config.update({
  logger: process.stdout,
  region: 'ap-northeast-1'
});

var r53 = new AWS.Route53();

var params = {
  HostedZoneId: 'hostedzone/XXXXXXXXXXXXXX',
  ChangeBatch: {
    Changes: [
      {
        Action: 'UPSERT',
        ResourceRecordSet: {
          Name: 'foobar.io.example.org',
          Type: 'CNAME',
          ResourceRecords: [
            { Value: 'ec2-xxx-xxx-xxx-xxx.ap-northeast-1.compute.amazonaws.com' }
          ]
        },
      }
    ]
  }
};

r53.changeResourceRecordSets(params, function(err, res) {
  console.log(err, res);
});

join_cluster.js

var Serf = require('node-serf');
var AWS = require('aws-sdk');

AWS.config.update({
  logger: process.stdout,
  region: 'ap-northeast-1'
});

var serf = Serf.connect({ port: 7373 });

var ec2 = new AWS.EC2();
var elb = new AWS.ELB();

elb.describeInstanceHealth({ LoadBalancerName: 'your-balancer-name' }, function(err, res) {
  if (err) {
    return console.error(err.name, err.stack);
  }
  var instanceIds = res.InstanceStates.map(function(item) {
    return item.InstanceId;
  });
  ec2.describeInstances({ InstanceIds: instanceIds }, function(err, res) {
    if (err) {
      return console.error(err.name, err.stack);
    }
    var privateIpAddrs = res.Reservations.map(function(item) {
      return item.Instances.map(function(item) {
        return item.PrivateIpAddress + ':7946';
      });
    });
    serf.join({ Existing: [].concat.apply([], privateIpAddrs) });
  });
});

members.js

var sha1 = require('sha1');
var Serf = require('node-serf');
var serf = Serf.connect({ port: 7373 });

serf.on('connect', function() {
  serf.members(function(members) {
    var hosts = members.Members.map(function(item) {
      return sha1(item.Name).slice(0, 10) + '.io.example.org';
    });
    console.log(hosts);
    serf.destroy();
  });
});