Rack::Session::Redic

Rack::Session::Redic provides simple cookie based session management. Session data is stored in Redis via the Redic gem. The corresponding session key is maintained in the cookie.

Options include:

• :marshaller - You may optionally supply the class/module you would like to use when marshalling objects in and out of Redis. All that is required is that this class respond to the load and dump methods, returning the session hash and a string respectively.
• :url - Additionally, you may pass in the URL for your Redis server. The default URL is fetched from the ENV as REDIS_URL in keeping with Heroku and others' practices.
• :expire_after - Finally, expiration will be passed to the Redis server via the 'EX' option on 'SET'. Expiration should be in seconds, just like Rack's default handling of the :expire_after option. This option will refresh the expiration set in Redis with each request.

Any other options will get passed to Rack::Session::Abstract::Persisted.

Installation

Add this line to your application's Gemfile or gems.rb file:

gem 'rack-redic', require: 'rack/session/redic'

And then execute:

bundle

Or install it yourself as:

gem install rack-redic

Usage

Anywhere in your Rack application just add:

# Most basic usage.
use Rack::Session::Redic

# Optionally pass in a marshaller.
use Rack::Session::Redic, marshaller: Oj

# And/or pass in the URL of your Redis server.
use Rack::Session::Redic, marshaller: Oj, url: 'redis://host:port'

# And/or pass in the expiration. (1_800 is 30 minutes in seconds)
use Rack::Session::Redic, marshaller: Oj, url: 'redis://host:port', expire_after: 1_800

Custom Marshallers

Since the class/module passed as :marshaller only needs to respond to the methods load and dump, you can create any kind of marshaller you would like. I've included examples for MessagePack and Oj here as reference.

MessagePack

require 'msgpack'

MessagePack::DefaultFactory.register_type(0x00, Symbol)

module MessagePackMarshaller
  def self.dump(object)
    MessagePack.pack(object)
  end

  def self.load(string)
    MessagePack.unpack(string)
  end
end

Then, while adding it your Rack application.

use Rack::Session::Redic, marshaller: MessagePackMarshaller

NOTE: MessagePack serializes symbols as strings by default so I suggest customizing that behavior per their instructions. You can read more about MessagePack's extension formats here.

Oj

Oj responds to load and dump by default so there's no adapter module needed.

use Rack::Session::Redic, marshaller: Oj

License

The gem is available as open source under the terms of the MIT License.