Loops until given domain is resolvable. Used to check when new domains are live.

dnscheck.rb

require 'resolv'
require 'date'

unless @domain = ARGV.first
  puts "DNS Checker\n\n"

  puts "Performs a DNS lookup on a domain until it can be resolved.\n\n"

  puts "USAGE:"
  puts " ruby #{__FILE__} <domain> [<sleep>]\n\n"

  puts "The optional sleep argument defines the amount of time to wait between each"
  puts "lookup attempt. If not specified, it defaults to 60 seconds."
  exit
end

@sleep = (ARGV[1] || 60).to_i
puts "[#{DateTime.now}] Started DNS check for #{@domain}..."

# Public: Attempt to lookup the domain
#
# Returns IP address if resolved or false
def attempt_lookup
  Resolv.getaddress(@domain)
rescue Resolv::ResolvError
  false
end

begin
  until ip_address = attempt_lookup
    print '.'
    sleep @sleep
  end

  puts "[#{DateTime.now}] Success: #{@domain} is pointing at #{ip_address}!"
  puts "[#{DateTime.now}] Done."
rescue => e
  puts "[#{DateTime.now}] Error:   #{e.class}"
  puts "[#{DateTime.now}] Message: #{e.message}"
  puts "[#{DateTime.now}] Canceled."
end