transform.rb

#!/bin/ruby

require 'yaml'

raw_data =
%Q{
apps:
  appname:
    workgroup1:
      data:
        foo: bar
        zed: zot
        ding: dong
      hosts:
        - vm01
        - vm02
    workgroup2:
      data:
        foo: bar1
        zed: zot1
        ding: dong1
      hosts:
        - vm03
        - vm04
}

data = YAML.load(raw_data)
data["apps"]["appname"].keys.each do |key|
  puts("#Workgroup: #{key}")
  data["apps"]["appname"][key]["hosts"].each do |host|
    data["apps"]["appname"][key]["data"].each do |key, value|
      puts("#{host}:#{key}:#{value}")
    end
  end
end