gistfile1.rb

      # from the docs -- 
      # returns an Array on multiple servers and a 
      # AWS::EC2::Instance for a single server.
      instances = aws_ec2.instances.create(
        :count            => @number_of_servers,
        :image_id         => ec2.ami,
        :security_groups  => ec2.security_groups,
        :key_name         => ec2.ssh_key
      )

      p instances.class # Actually an AWS::Core::Data::List in the multiple case
      # box it if it's not an array. AWS::Core::Data::List is a kind of Array.
      instances = [instances] unless instances.kind_of?(Array)

      #
      # There are instances where AWS won't acknowledge a created instance
      # right away. Let's make sure the API server knows they all exist before
      # moving forward.
      #

      unresolved_instances = instances.dup # Returns new Array for Array, returns self for AWS::Core::Data::List

      until unresolved_instances.empty?
        instance = unresolved_instances.shift

        unless (instance.status rescue nil)
          if_debug(3) do
            $stderr.puts "API server doesn't think #{instance.id} exists yet."
          end

          sleep 0.3
          unresolved_instances.push(instance)
        end
      end

      p instances # empty for AWS::Core::Data::List

      # by my best calculation this bug cost the company around $150 to find, and that's long before my salary comes into play.