Quick Launch Amazon Linux

launch.rb

#!/usr/bin/env ruby
# Quickly launch Amazon Linux EC2 instance in Default VPC.
# Required to be set the below environment variables
# - AWS_DEFAULT_REGION
# - AWS_ACCESS_KEY
# - AWS_SECRET_KEY
#
# Usage : ruby launch.rb

require 'aws-sdk'

# security group id to be attached to the instance
secgroup_id = "sg-xxxxxxx"
# KeyPair name to be used
keypair_name = "keypair"

ec2 = AWS::EC2.new
image_id = ""
AWS.memoize do
  image_id = ec2.images.with_owner('amazon')
            .filter("name", "amzn-ami-hvm-*-ebs")
            .sort{|a, b| b.name <=> a.name }
            .first.image_id
end

resp = ec2.instances.create(image_id: image_id,
                     security_group_ids: [secgroup_id],
                     key_pair: ec2.key_pairs[keypair_name],
                     instance_type: "t2.micro",
                     associate_public_ip_address: true)
puts "Launched instance : #{resp.id}"
puts "waiting for acquiring Public IP Address..."

# wait until Public IP Address is assigned to the launched instance.
i = 1
while ec2.instances[resp.id].ip_address.nil?
  if i > 10
    raise RuntimeError
  end
  sleep 2 ** i
  i += 1
end

puts "Got IP Address. You can connect via 'ssh -i ~/.ssh/#{keypair_name}.pem ec2-user@#{resp.ip_address}' in a few moments."