Rake task to update Amazon Route53 DNS from by Chef node search

update_dns.rake

# -*- ruby -*-

# Needs following parameters configured in rake.rb:
# DNS_DOMAIN: domain for which to set entries, including trailing dot
# (e.g. "example.com.")
# DNS_ATTRIBUTE: attribute containing hostname to CNAME to, defaults
# to 'fqdn'; for EC2, use "ec2.public_hostname"
# DNS_ENTRIES: hash mapping hostname to node search query,
# e.g. {'buildbot' => 'recipes:buildbot', 'monitoring' =>
# 'roles:monitoring'}

DNS_ATTRIBUTE ||= 'fqdn'

desc "Update Route53 entries within #{DNS_DOMAIN}"
task :update_dns do
  require 'escape'
  require 'fog'
  require 'json'

  # Build up table of DNS entries
  dns = {}
  DNS_ENTRIES.each_pair do |hostname, query|
    q = Escape::shell_single_word query
    r = JSON::load `knife search node #{q} -a #{DNS_ATTRIBUTE}`
    if r["total"].zero?
      puts "WARN: No host found for #{query} - not touching #{hostname}"
    else
      dns["#{hostname}.#{DNS_DOMAIN}"] = r["rows"][0][DNS_ATTRIBUTE]
      if r["total"] != 1
        puts "WARN: Multiple results found for #{query}, using first"
      end
    end
  end

  if ENV['VERBOSE']
    require 'pp'
    pp dns
  end

  # https://github.com/geemus/excon/issues#issue/13
  # "certificate verify failed" workaround
  Excon.ssl_verify_peer = false

  r53 = Fog::DNS.new(:provider => "AWS",
                     :aws_access_key_id => AWS_ACCESS_KEY_ID,
                     :aws_secret_access_key => AWS_SECRET_ACCESS_KEY)
  zone = r53.zones.find { |z| z.domain == DNS_DOMAIN }

  zone.records.find_all { |r|
    not dns.keys.include? r.name
  }.each do |r|
    puts "- #{r.name}"
    r.destroy
  end

  zone.records.find_all { |r|
    (dns.keys.include? r.name) and (r.ip[0] != dns[r.name])
  }.each do |r|
    puts "* #{r.name} -> #{dns[r.name]}"
    r.ip = [ dns[r.name] ]
    r.save
  end

  (dns.keys - zone.records.map { |r| r.name }).each do |name|
    puts "+ #{name} -> #{dns[name]}"
    zone.records.create(:ip => dns[name],
                        :name => name,
                        :type => "CNAME")
  end
end