Rack::Authorize is a Rack middleware to authorize api access. We know there is Cancan which is a great authorization library for Ruby on Rails. But the rules of Cancan are defined for Ruby Class, when we create web services, it's a common task to restrict the access to api endpoints. That's what Rack::Authorize focus on, it's only used for api stuff. Rack::Authorize can be used in any Ruby web framework since it's a Rack middleware. Thanks Rack.

Add this line to your application's Gemfile:

gem 'rack-authorize', :git => '[email protected]:yanguango/rack-authorize.git'

This gem is still in development, so it's not posted to rubygems.org

And then execute:

$ bundle

Or install it yourself as:

$ gem install rack-authorize

You can define ability with can macros, which inspired by Cancan. Also you can use can_get, can_post helpers to define conveniently.

class Ability
  include Rack::Authorize::Ability

  def initialize(user)
    can :get, "/api/articles" 
    # user can access "/api/things" with GET method
    
    can :post, "/api/articles" if user.role == 'writer' 
    # user can post article if he is a writer
    
    can :all, "/api/comments" 
    # user can access "/api/comments" with any methods
    
    can_get, :all 
    # user can access all api endpoints with GET method
    
    can_all, :all if user.is_super? 
    # super user has no restriction
  end
end

As a Rack middleware, you can use Rack::Authorize in any Rack compatible framework, what you need to do is just use this middleware at appropriate position.

use Rack::Authorize do |method, path|
  ability = Ability.new(@current_user)
  ability.can?(method, path)
end

class App < Sinatra::Base
  use Rack::Auth::Basic do |username, password|
    @current_user ||= User.authenticate!(username, password)
  end

  use Rack::Authorize do |method, path|
    ability = Ability.new(@current_user)
    ability.can?(method, path)
  end

  get '/api' do
    "Hello World!"
  end
end

class AdminAPI < Grape::API

  version 'v1', using: :header
  format :json
  prefix 'api'
  
  namespace :admin do
    use Rack::Auth::Basic do |username, password|
      @current_use ||= AdminUser.authenticate!(username, password)
    end

    use Rack::Authorize do |method, path|
      ability = Ability.new(@current_user)
      ability.can?(method, path)
    end
    
    resources :users do
      get '/' do
        "Hello World!"
      end
    end
  end
end

• Path prefix
• Api endpoint whitelist
• ...

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/yanguango/rack-authorize. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

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