Capfile

# plugins, recipes, clusters, etc
Dir['lib/*', 'recipes/*', 'config/groups/*'].each {|plugin| load plugin}

# default settings
load 'config/settings'

collins_selector.rb

require 'collins_client'

class CollinsSelector
  attr_reader :collins

  def initialize config
    @collins = Collins::Client.new config
  end

  def select attribute, selector
    collins.find(defaults.merge(selector)).collect do |node|
      node.send attribute
    end
  end

  def selectors selectors
    defaults.merge! selectors
  end

  def method_missing method, *args
    missing_method = method.to_s

    if missing_method.start_with? 'select_'
      select missing_method.sub('select_', ''), *args
    else
      collins.send method, *args
    end
  end

  private
  def defaults
    @defaults ||= {
      :type      => :server_node.upcase,
      :status    => :allocated, 
      :operation => :and,
      :size      => 10 ** 5,
      :details   => true,
    }
  end
end

example.rb

task :hadoop_pb do
  collins.selectors :primary_role => :hadoop, :pool => :peanutbutter

  # namenode / job tracker
  server collins.select_hostname(:secondary_role => /^namenode$/).first, :namenode, :jobtracker

  # secondary namenode
  role :secondary_namenode, collins.select_hostname(:secondary_role => :secondary_namenode).first

  # datanodes / task trackers
  collins.select_hostname(:secondary_role => :datanode).each do |node|
    server node, :datanode, :tasktracker
  end
end

helpers.rb

require File.expand_path File.join File.dirname(__FILE__), 'hash.rb'
require 'colored'
require 'ipaddr'

# helpers
def info *messages
  puts messages.join("\s").blue
end

def warn *messages
  puts messages.join("\s").yellow
end

def error *messages
  puts messages.join("\s").red
end

def fatal *messages
  abort messages.join("\s").red
end

def collins_group_assets
  find_servers_for_task(current_task).collect do |host|
    collins.find hostname: host,
                 details:  true,
                 size:     10000
  end.flatten
end

settings.rb

# ssh options
ssh_options[:forward_agent] = true
ssh_options[:keys] = Dir.glob(File.join(ENV['HOME'], '.ssh', 'id_*')).reject do |key|
  key.start_with? '.'
end

# misc options
default_run_options[:pty]   = true

# collins selector
set :collins_config, '~/.collins.yaml'
set :collins_yaml, YAML.load_file(File.expand_path(collins_config))
set :collins, CollinsSelector.new(collins_yaml[:collins] || collins_yaml['collins'])