Tsorting docker json files

dockercvr.rb

#!/usr/bin/env ruby

require 'json'
require 'tsort'

class Hash
  include TSort
  alias tsort_each_node each_key
  def tsort_each_child(node, &block)
    fetch(node).each(&block)
  end
end

@layers = {}
@images = {}

Dir.glob("./files/rmq/*/json") do |filename|
  json = File.open(filename, "r")
  hash = JSON.parse(json.read, :symbolize_names => true)

  @layers[hash[:id]] = hash[:parent] ? [hash[:parent]] : []
  @images[hash[:id]] = hash
end

@sorted_list = @layers.tsort

@sorted_list.each do |id|
  puts ""
  command = @images[id][:container_config][:Cmd]
  puts command.join(' ') unless command.nil?
end