DNS server backed by Redis, and resolves EC2 instance names

server.js

var dns = require('native-dns');
var server = dns.createServer();
var client = require('redis').createClient();
var aws = require('aws-lib');


server.on('request', function(req, res){
  var parts = req.question[0].name.split('.');
  var tag = parts[0];
  var authority = parts.slice(1).join('.');
  client.hgetall('authority:' + authority, function(err, reply) {
    if (err || reply === null) {
        res.header.rcode = 3; // not found
        res.send();
        return;
    }
    var ec2 = aws.createEC2Client(reply['id'], reply['secret'], {version: '2010-08-31'});
    var filter = {'Filter.1.Name': 'tag:Name', 'Filter.1.Value.1': tag};
    ec2.call('DescribeInstances', filter, function(err, result) {
        if (err || !('item' in result.reservationSet)) {
            res.header.rcode = 3; // not found
            res.send();
            return;
        }
        var answer;
        if (req.question[0].type === 1) { // A
          answer = dns.A({
            name: req.question[0].name,
            address: result.reservationSet.item.instancesSet.item.ipAddress,
            ttl: 600
          });
        } else if (req.question[0].type === 5) { //CNAME
          answer = dns.CNAME({
            name: req.question[0].name,
            data: result.reservationSet.item.instancesSet.item.dnsName + '.',
            ttl: 600
          });
        }
        if (answer) {
          res.answer.push(answer);
        }
        res.send();
    });
  });
});

server.serve(53);