Use rake and knife-solo to cook or bootstrap multiple EC2 instances. Automatically load EC2 IP addresses via the SDK

Gemfile

source 'https://rubygems.org'

gem 'rake'
gem 'aws-sdk'
gem 'dotenv'
gem 'chef'
gem 'librarian-chef'
gem 'knife-solo'
gem 'knife-solo_data_bag'

Rakefile

# Rather than running knife solo cook for each individual instance, this script loads the instance IPs via the AWS SDK and
# shells out to knife solo. For less than 5 total instances, this seems to make sense.
#
# We'll be using the same tags that cap-ec2 uses: Name, Roles, and Stage. We'll also have a Bootstrapped tag,
# which should default to false. Make sure you set that on new instances!

require 'aws-sdk'
require 'dotenv/tasks'

AWS.config(
  :access_key_id => ENV['AWS_ACCESS_KEY_ID'],
  :secret_access_key => ENV['AWS_SECRET_ACCESS_KEY']
)

ENVIRONMENT = ENV['ENVIRONMENT'].to_s != '' ? ENV['ENVIRONMENT'] : 'beta'

def ec2
  @ec2 ||= AWS::EC2.new
end

def running_instances
  @running_instances ||= ec2.instances.filter('instance-state-name', 'running').tagged("Stage").tagged_values(ENVIRONMENT)
end

def make_opts(hash)
  hash.inject([]) do |m, kv|
    m << "--#{kv[0]} '#{kv[1]}'"
    m
  end.join ' '
end

def default_opts(instance)
  # We use the Roles tag to determine what chef roles should be applied
  roles = instance.tags["Roles"].split(',')
  run_list = roles.map {|r| "role[#{r.strip}]" }.join(",")
  # Use your own ssh key to connect
  make_opts('identity-file' => '/full/path/to/public.pem',
            'environment' => ENVIRONMENT,
            # role[solo] is optional, nice to have a shared config role, though
.            'run-list' => "role[solo],#{run_list}")
end

desc "Cook all the EC2 instances"
task :cook do
  running_instances.each do |instance|
    sh "knife solo cook ec2-user@#{instance.ip_address} #{default_opts(instance)}"
  end
end

# knife solo bootstrap is a fairly slow task, because it installs chef omnibus.
desc "Bootstrap apps"
task :bootstrap do
  running_instances.tagged("Bootstrapped").tagged_values("false").each do |instance|
    sh "knife solo bootstrap ec2-user@#{instance.ip_address} #{default_opts(instance)}"
    instance.tags["Bootstrapped"] = true
  end
end