Rakefile

require 'rubygems'
require 'rake'
require 'rspec/core/rake_task'
require 'yaml'
require 'json'
require 'chef/run_list'

json_files = Dir::glob("./nodes/*.json")
Chef::Config[:cookbook_path] = './cookbook/'
Chef::Config[:role_path]     = './roles/'

desc "Run serverspec to all hosts"
task :default => 'serverspec:all'

host_run_list = {}

json_files.each do |json_file|  host_config = JSON.parse(File.read(json_file))
  host_name   = File.basename(json_file, ".json")
  host_run_list[host_name] = host_config["run_list"] || []
end
namespace :serverspec do

  ### start task
  task :all => host_run_list.keys
  host_run_list.keys.each do |target_host|
    desc "Run serverspec to #{target_host}"
    RSpec::Core::RakeTask.new(target_host.to_sym) do |t|
      ENV['TARGET_HOST'] = target_host
      target_run_list = host_run_list[target_host]
      recipes = Chef::RunList.new(*target_run_list).expand("_default", "disk").recipes
      t.pattern = ['cookbooks/{' + recipes.join(',') + '}/spec/*_spec.rb', "spec/#{target_host}/*_spec.rb"]
    end
  end
end

spec_helper.rb

require 'serverspec'
require 'pathname'
require 'net/ssh'
require 'yaml'
require 'json'

include Serverspec::Helper::Ssh
include Serverspec::Helper::DetectOS
include Serverspec::Helper::Attributes

RSpec.configure do |c|
  c.host   = ENV['TARGET_HOST']
  attr_set JSON.parse(File.read("./nodes/#{c.host}.json"))
  options  = Net::SSH::Config.for(c.host)
  user     = 'root'
  c.ssh    = Net::SSH.start(c.host, user, options)
  c.os     = backend.check_os
end