Production environment for Rails 3 on heroku with rack-cache

Gemfile

# Add this to your gem file

group :production do
  gem 'dalli'
  gem 'rack-cache', :require => 'rack/cache'
  gem 'rack-contrib', :require => 'rack/contrib'
end

production.rb

MyApp::Application.configure do
  # Settings specified here will take precedence over those in config/environment.rb

  # The production environment is meant for finished, "live" apps.
  # Code is not reloaded between requests
  config.cache_classes = true

  # Full error reports are disabled and caching is turned on
  config.consider_all_requests_local       = false
  config.action_controller.perform_caching = true

  # Specifies the header that your server uses for sending files
  # config.action_dispatch.x_sendfile_header = "X-Sendfile"

  # For nginx:
  config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect'

  # If you have no front-end server that supports something like X-Sendfile,
  # just comment this out and Rails will serve the files

  # See everything in the log (default is :info)
  # config.log_level = :debug

  # Use a different logger for distributed setups
  config.logger = Logger.new(STDOUT)

  # Use a different cache store in production
  config.cache_store = :dalli_store

  # Disable Rails's static asset server
  # In production, Apache or nginx will already do this
  config.serve_static_assets = false

  # Enable serving of images, stylesheets, and javascripts from an asset server
  # config.action_controller.asset_host = "http://assets.example.com"

  # Disable delivery errors, bad email addresses will be ignored
  # config.action_mailer.raise_delivery_errors = false
  config.action_mailer.default_url_options = { :host => 'myapp.heroku.com' }

  # Enable threaded mode
  # config.threadsafe!

  # Enable locale fallbacks for I18n (makes lookups for any locale fall back to
  # the I18n.default_locale when a translation can not be found)
  config.i18n.fallbacks = true

  # Send deprecation notices to registered listeners
  config.active_support.deprecation = :notify

  # Remove Cache-Control header so varnish does not cache anything
  config.middleware.use Rack::ResponseHeaders do |headers|
    headers.delete('Cache-Control')
  end

  # Use Dalli as the rack-cache metastore
  $cache = Dalli::Client.new
  config.middleware.use ::Rack::Cache, :metastore => $cache, :entitystore => 'file:tmp/cache/entity'
end