gistfile1.rb

#!/usr/bin/env ruby
require 'rubygems'
require 'highline'
require 'yaml'

ENV['HOME']

user_name = ARGV[1] || 'root'
key_name = ARGV[2]


valid_host_regex = /ec\d+-\d{1,3}-\d{1,3}-\d{1,3}-\d{1,3}(\..*)?/

ssh_dir = "#{ENV['HOME']}/.ssh/"
keys = Dir.glob("#{ssh_dir}id_r*").reject{|p| p =~ /\.pub$/}

key_names = keys.map{|k| k.sub(ssh_dir, '')}
key = key_names.detect{|k| k =~ /id_rsa-#{key_name}/} if key_name

ui = HighLine.new


host = ARGV[0]
known_hosts_file = File.dirname(__FILE__)+'/.known_ec2_hosts'
if File.exists?(known_hosts_file)
  known_hosts = YAML::load_file(known_hosts_file)
else
  known_hosts = {}
end

available_hosts = known_hosts.keys
if host.nil? || (host == "")  || !(host =~ valid_host_regex)
  available_hosts << "enter new"
  ui.say(ui.color('Choose a host:',HighLine::BOLD))
  host = ui.choose(*available_hosts)
end

if (host == "enter new")
  host = ui.ask("ok, enter a host:  ") { |q| q.validate = valid_host_regex }
end

case host.count('.')
when 0
  host += ".compute-1.amazonaws.com"
when 1
  host += ".amazonaws.com"
when 2
  host += ".com" 
end

key = known_hosts[host]

unless key
  if key_names.length > 1
    ui.say(ui.color('Choose a key:',HighLine::BOLD))
    key = ui.choose(*key_names)
  else
    key = key_names.first
  end
end

known_hosts[host] = key

File.open(known_hosts_file, "w") { |f|
  YAML.dump(known_hosts, f)
}


key_path = "#{ssh_dir}#{key}"



Dir.chdir("/Users/lasto/.ssh")
ssh_known_hosts = File.read("known_hosts")
ssh_known_hosts.gsub!(/^[^\n]*#{host}[^\n]*$\n?/, '')
File.open("known_hosts", 'w'){|f| f.write ssh_known_hosts}
login = "#{user_name}@#{host}"

cmd = "ssh -i #{key_path} #{login}"

puts cmd
Kernel.exec cmd