ec2_checker.rb

gem 'aws-sdk'
require 'rubygems'
require 'aws-sdk'

ec2 = AWS::EC2.new(:access_key_id => nil, 
                   :secret_access_key => nil,
                   :proxy_uri      => ENV['HTTPS_PROXY'] || ENV['https_proxy'] || ENV['HTTP_PROXY'] || ENV['http_proxy'])
ec2.regions.each do |region|
  reg = ec2.regions[region.name]
  reg.instances.each do |instance|
    if instance.status == :running
      puts instance.tags["Name"] || instance.dns_name                                                                                                            
    end 
  end 
end