Tiny static serving server written in Ruby

config.ru

%w[ logger yaml rack eventmachine ].each(&method(:require))

log = Logger.new(STDOUT)
config = YAML.load_file('config.yml')
Thread.new{ EM.run }

templates = config['storage']['templates'].map{ |tpl| config['storage']['root'] + tpl }
cache = templates.map{ |tpl| Dir[tpl] }.inject(:+).keep_if{ |f| File.file?(f) }
cache = Hash[cache.map do |f|
  l = config['storage']['root'].length
  [f.slice(l, f.length - l), File.binread(f)]
end]

run ->(env){
  file = env['REQUEST_PATH']
  return [404, {}, ['404 Not Found']] unless cache.keys.include?(file)

  headers = {}
  ext = '.' << file.split(?.).last
  headers['Content-Type'] = Rack::Mime::MIME_TYPES[ext] || 'text/plain'
  headers['Content-Length'] = cache[file].length.to_s

  EM.defer do
    log.info 'Performing an async call to ' << config['callback']['url'] % file
  end

  [200, headers, [cache[file]]]
}

config.yml

storage:
  root: '/usr/share/web/public'
  templates:
    - '/**/*'
callback:
  url: 'http://count.example.com/?path=%s'