em-powerdns¶ ↑

You can use this plus the unix program PowerDNS to make a custom DNS server with the lookup done by a ruby script you write.

Even though the actual PowerDNS pipe backend is synchronous, using this will allow a script to start up other side tasks, logging or stats for example, without interrupting the scripts ability to serve more requests.

Include EM::P::PowerDNS in a module or class to use it as a PowerDNS backend.

module RedisBackend
  include EM::P::PowerDNS

  def receive_query(query)
    # make some logic here to resolve the DNS
    ip = redis[query.qname]
    data query.qname, query.qclass, :A, 3600, 1, ip
    super
  end

  def redis
    @redis ||= Redis.new
  end
end

EM.run { EM.open_keyboard(RedisBackend) }

PowerDNS uses stdin to send all it’s queries so EM.open_keyboard does exactly what we need.

Copyright © 2010 Martin Emde. See LICENSE for details.