Print out useful information about running ec2 instances

ec2-dns.rb

#!/usr/bin/env ruby
#
# This ruby script will print out useful information about running ec2
# instances
#
# Reads AWS access and secret keys from environment variables
#
# Requires the amazon-ec2 gem (gem install amazon-ec2)
#
# Author: Bryan J Swift (bryan.j.swift@gmail.com)

require 'rubygems'
require 'AWS'

ACCESS_KEY_ID = ENV['EC2_ACCESS']
SECRET_ACCESS_KEY = ENV['EC2_SECRET']

ec2 = AWS::EC2::Base.new(:access_key_id => ACCESS_KEY_ID, :secret_access_key => SECRET_ACCESS_KEY)

ec2.describe_instances.reservationSet.item.each do |instance|
  terminated = instance.instancesSet.item[0].instanceState.name == "terminated"
  dns = instance.instancesSet.item[0]['dnsName']
  instanceId = instance.instancesSet.item[0]['instanceId']
  name = "'" + instance.instancesSet.item[0].tagSet.item.reject { |t| t.key != "Name" }[0].value + "'"
  vals = [name, instanceId, dns]
  if !terminated then
    puts vals.join(" -- ")
  end
end