slice_dyndns.rb

#!/usr/bin/env ruby
require 'optparse'
require 'logger'
require 'open-uri'

begin
  require 'active_resource'
rescue LoadError => e
  # active_resource has probably been installed via rubygems
  # which, of course, does not put it on the search path
  # silly package manager :-(
  begin
    require 'rubygems'
    require 'active_resource'
  rescue LoadError
    puts "you need to install the active_resource gem"
    puts "see http://bit.ly/3Bnnwo for active resource info"
    exit 1
  end
end

FLAGS = {}
OptionParser.new do |opts|
  opts.banner = "Usage: #$0 -H <host name> -k <api key>"
  opts.on("-H", "--host HOST", "Host name") do |host| 
    host = host + "." unless host =~ /\.$/
    FLAGS[:host] = host
  end  
  opts.on("-k", "--api-key KEY", "Slicehost API Key") {|FLAGS[:key]|}
  opts.on("-v", "--verbose", "Log HTTP requests") do
    ActiveResource::Base.logger = Logger.new(STDERR)
  end
  opts.on("-h", "--help", "Show help") { FLAGS[:help] = true }
  opts.on_tail "See http://articles.slicehost.com/api for API details"

  opts.parse!  
  if !FLAGS[:host] or !FLAGS[:key] or FLAGS[:help]
    puts opts
    exit 1
  end
end

IP_PAT = Regexp.compile("([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+)")

DNS_VAL = if `host #{FLAGS[:host]}` =~ IP_PAT
            $1
          else
            puts "unable to locate host #{FLAGS[:host]}"
            exit 1
          end

IP = open("http://checkip.dyndns.org/") do |i|
  unless i.readlines.join(" ") =~ IP_PAT
    puts "did not find a valid IP address, exiting!"
    exit 1 
  end
  $1
end

unless DNS_VAL == IP
  class Record < ActiveResource::Base 
    self.site = "https://#{FLAGS[:key]}@api.slicehost.com/"
  end

  r =  Record.find(:first, :params => { 
                     :record_type => 'A', 
                     :name => FLAGS[:host] 
                   })
  unless r
    puts "Failed to find an A record for #{FLAGS[:host]}"
    exit 1
  end

  r.data = IP
  if r.save
    puts "updated IP to #{IP}"
  else
    puts "failed to update IP to #{IP}"
    exit 1
  end
else
  puts "nothing to be done"
end