unconstrained_cookbooks.rb

require 'chef'
Chef::Config.from_file('knife.rb')
envs = Chef::Environment.list.keys
q = Chef::Search::Query.new
envs.each do |e|
  constrained_cookbooks = Chef::Environment.load(e).cookbook_versions.keys
  all_cookbooks =[]
  nodes = q.search(:node, "chef_environment:#{e}").first.reject(&:nil?)
  nodes.select{|n| n.attribute?(:recipes)}.each do |n|
    n.recipes.map{|r| r.split('::')[0]}.each do |cookbook|
      all_cookbooks << cookbook unless all_cookbooks.include?(cookbook)
    end
  end
  puts "Environment: #{e} Unconstrained cookbooks: #{all_cookbooks - constrained_cookbooks} "
end