This snippet creates an instance on AWS EC2.

aws-launch-instance.rb

# How to execute:
# 1. Make sure you have optparse and aws-sdk gem installed
# 2. Run: ruby aws-launch-instance.rb -a YOUR-ACCESS_KEY -s YOUR-SECRET-KEY -r eu-central-1 -t t2.micro

require 'optparse'
require 'aws-sdk'

# Collect parameters
options = {}
optparse = OptionParser.new do |opts|
  opts.on('-a', '--aws-access-key INSTANCE-REGION', "Your AWS Access Key") do |option|
    options["aws-access-key"] = option
  end

  opts.on('-s', '--aws-secret-key INSTANCE-REGION', "Your AWS Secret Key") do |option|
    options["aws-secret-key"] = option
  end

  opts.on('-r', '--instance-region INSTANCE-REGION', "Region where Instance should be launched") do |option|
    options["instance-region"] = option
  end

  opts.on('-t', '--instance-type INSTANCE-TYPE', "Instance Type") do |option|
    options["instance-type"] = option
  end
end

optparse.parse!

if options["aws-access-key"].nil? or options["aws-secret-key"].nil? or options["instance-region"].nil? or options["instance-type"].nil?
  puts optparse
  exit
end

access_key = options["aws-access-key"]
secret_key = options["aws-secret-key"]
instance_type = options["instance-type"]
instance_region = options["instance-region"]


# Setting credentials - Usually I'd put this on ~/.aws/credentials file, or set env vars through EXPORT for security reasons, 
# but I kept it here because as asked before
Aws.config.update({
    credentials: Aws::Credentials.new("#{access_key}", "#{secret_key}")
})

# Sets the region
ec2 = Aws::EC2::Resource.new(region: "#{instance_region}")

puts "Creating your instance, please wait..."

# Finally creates the instance
launched_instance = ec2.create_instances({
  image_id: 'ami-82be18ed', # AMI Linux
  min_count: 1,
  max_count: 1,
  instance_type: "#{instance_type}"
})

# Wait for the instance to be created
ec2.client.wait_until(:instance_status_ok, {instance_ids: [launched_instance[0].instance_id]})

# Return STDOUT
puts "Your new Instance has the Id " << launched_instance[0].instance_id << " and was launched at " << launched_instance[0].launch_time.to_s