Introducing the instant_ec2 gem

require 'instant_ec2'

e = InstantEC2.new credentials: ['youraccesskey', 'yourprivatekey']

# look for my Windows AMI and then launch the instance

# query my images (the images which are displayed in
#  the EC2 Management Console web page)
#
e.images
#=> [{:image_name=>"Windows_Serve...", :instance_id=>"i-327f0f84"}, {:image_...


e.start 'windows' 

# Notify me when the Windows EC2 instance is running and
#   display the public IP address
#
e.on_running {|ip| puts 'instance is now accessible from ' + ip}
#=> instance is now accessible from 54.84.182.27  

e.stop # stop the instance that is currently running

# Notify me when the Windows EC2 instance has successfully stopped
#
e.on_stopping { puts 'the instance has now stopped'}