# File lib/deltacloud/drivers/ec2/ec2_driver.rb, line 160
        def realms(credentials, opts={})
          ec2 = new_client(credentials)
          zone_id = opts ? opts[:id] : nil
          safely do
            return ec2.describe_availability_zones(zone_id).collect do |realm|
              convert_realm(realm)
            end
          end
        end