Launching EC2 instance with aws-sdk gem

launch_instance.rb

#!/usr/bin/ruby

# README
# gem install aws-sdk
# add this to bashrc
# export HT_DEV_AWS_ACCESS_KEY_ID=????
# export HT_DEV_AWS_SECRET_ACCESS_KEY=????
# put your pem file in ~/.ssh and chmod 0400
# for more info see; https://rubygems.org/gems/aws-sdk

require 'rubygems'
require 'aws-sdk'

AWS.config(:access_key_id     => ENV['HT_DEV_AWS_ACCESS_KEY_ID'],
           :secret_access_key => ENV['HT_DEV_AWS_SECRET_ACCESS_KEY'])

ec2                 = AWS::EC2.new.regions['eu-west-1']            # choose region here
ami_name            = '*ubuntu-lucid-10.04-amd64-server-20110719'  # which AMI to search for and use
key_pair_name       = 'matt-housetrip-aws'                         # key pair name
private_key_file    = "#{ENV['HOME']}/.ssh/matt-housetrip-aws.pem" # path to your private key
security_group_name = 'housetrip-basic'                            # security group name
instance_type       = 't1.micro'                                   # machine instance type (must be approriate for chosen AMI)
ssh_username        = 'ubuntu'                                     # default user name for ssh'ing

# find the AMI based on name (memoize so only 1 api call made for image)
image = AWS.memoize do
  ec2.images.filter("root-device-type", "ebs").filter('name', ami_name).first
end

if image
  puts "Using AMI: #{image.id}"
else
  raise "No image found matching #{ami_name}"
end

# find or create a key pair
key_pair = ec2.key_pairs[key_pair_name]
puts "Using keypair #{key_pair.name}, fingerprint: #{key_pair.fingerprint}"

# find security group
security_group = ec2.security_groups.find{|sg| sg.name == security_group_name }
puts "Using security group: #{security_group.name}" 

# create the instance (and launch it)
instance = ec2.instances.create(:image_id        => image.id, 
                                :instance_type   => instance_type,
                                :count           => 1,
                                :security_groups => security_group,
                                :key_pair        => key_pair)
puts "Launching machine ..."

# wait until battle station is fully operational
sleep 1 until instance.status != :pending
puts "Launched instance #{instance.id}, status: #{instance.status}, public dns: #{instance.dns_name}, public ip: #{instance.ip_address}"
exit 1 unless instance.status == :running

# machine is ready, ssh to it and run a commmand
puts "Launched: You can SSH to it with;"
puts "ssh -i #{private_key_file} #{ssh_username}@#{instance.ip_address}"
puts "Remember to terminate after your'e done!"
           
# clean up with the following (terminates the machine)
# instance.delete