cachepolicy.rb

class CachePolicy < Sinatra::Base

  # always forward the request downstream immediately (before processing routes)
  before { forward }

  # anything with a cache breaking timestamp gets an insanely long max-age
  get '/public/*' do
    pass unless request.query_string =~ /^\d+$/
    response['Cache-Control'] = 'public, max-age=1000000000'
  end

  # PNGs get a 5 minute ttl
  get '/public/*.png' do
    response['Cache-Control'] = 'public, max-age=300'
  end

  # everything else is private
  get '/*' do
    response['Cache-Control'] = 'private'
  end
end