List KVM domains and their IPs. Note that the mac and IP must be in the arp table

getdomtoip.rb

#!/usr/bin/ruby

require 'libvirt'
require 'xml'

def maptoip(mac,vm)
  IO.popen("ip neigh").each do | line|
    if (line.split(/\s+/)[4] == mac)
      puts "#{line.split(/\s+/)[0]} - #{mac} - #{vm}"
      break
    end
  end
end

conn = Libvirt::open('qemu:///system')

conn.list_domains.each do |domid|
  dom = conn.lookup_domain_by_id(domid)
  parser = XML::Parser.string(dom.xml_desc)
  doc = parser.parse
  doc.find('//devices/interface').each do |s|
    s.each do |node|
      maptoip(node[:address],dom.name)
    end
  end
end