csshX wrapper to log into all running servers in an AWS security group

aws_csshx.rb

#!/usr/bin/env ruby
require 'right_aws'

EC2_PRIVATE_KEY = ENV['EC2_PRIVATE_KEY']
AWS_ACCESS_KEY = ENV['AWS_ACCESS_KEY']
AWS_SECRET_KEY = ENV['AWS_SECRET_KEY']

def group
  @group ||= ARGV[0]
end

def csshx_exists?
  `which csshx > /dev/null 2>&1`
end

def env_variables_exist?
  EC2_PRIVATE_KEY && AWS_ACCESS_KEY && AWS_SECRET_KEY
end

def aws_servers
  @ec2_api ||= RightAws::Ec2.new(AWS_ACCESS_KEY, AWS_SECRET_KEY)

  @ec2_api.describe_instances.reject{|i| i[:aws_state] != "running"}.map do |instance|
    instance[:dns_name] if instance[:groups].map{|g| g[:group_name]}.include?(group)
  end.compact
end

abort('csshx is required') unless csshx_exists?
abort('CERT_LOCATION, AWS_ACCESS_KEY and AWS_SECRET_KEY environment variables must all be set') unless env_variables_exist?
abort('Must specify a group') if group.nil?

`csshx --login root --ssh_args="-i #{EC2_PRIVATE_KEY}" #{aws_servers.join(' ')}`