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Real HTTP Caching for Ruby Web Apps
Latest commit f96febe @grosser grosser changes


Rack::Cache is suitable as a quick drop-in component to enable HTTP caching for Rack-based applications that produce freshness (Expires, Cache-Control) and/or validation (Last-Modified, ETag) information:

  • Standards-based (RFC 2616)
  • Freshness/expiration based caching
  • Validation (If-Modified-Since / If-None-Match)
  • Vary support
  • Cache-Control: public, private, max-age, s-maxage, must-revalidate, and proxy-revalidate.
  • Portable: 100% Ruby / works with any Rack-enabled framework
  • Disk, memcached, and heap memory storage backends

For more information about Rack::Cache features and usage, see:

Rack::Cache is not overly optimized for performance. The main goal of the project is to provide a portable, easy-to-configure, and standards-based caching solution for small to medium sized deployments. More sophisticated / high-performance caching systems (e.g., Varnish, Squid, httpd/mod-cache) may be more appropriate for large deployments with significant throughput requirements.


gem install rack-cache

Basic Usage

Rack::Cache is implemented as a piece of Rack middleware and can be used with any Rack-based application. If your application includes a rackup (.ru) file or uses Rack::Builder to construct the application pipeline, simply require and use as follows:

require 'rack/cache'

use Rack::Cache,
  :metastore   => 'file:/var/cache/rack/meta',
  :entitystore => 'file:/var/cache/rack/body',
  :verbose     => true

run app

Assuming you've designed your backend application to take advantage of HTTP's caching features, no further code or configuration is required for basic caching.

Using with Rails

Add this to your config/environment.rb:

config.middleware.use Rack::Cache,
   :verbose => true,
   :metastore   => 'file:/var/cache/rack/meta',
   :entitystore => 'file:/var/cache/rack/body'

You should now see Rack::Cache listed in the middleware pipeline:

rake middleware

See the following for more information:

Using with Dalli

Dalli is a high performance memcached client for Ruby. More information at:

require 'dalli'
require 'rack/cache'

use Rack::Cache,
  :verbose => true,
  :metastore   => "memcached://localhost:11211/meta",
  :entitystore => "memcached://localhost:11211/body"

run app

License: MIT
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