Action Policy

Authorization framework for Ruby and Rails applications.

Composable. Extensible. Performant.

📑 Documentation

Action Policy is built by Evil Martians, an American design and engineering consultancy for developer tools, AI, and cybersecurity startups.

Resources

• RubyRussia, 2019 "Welcome, or access denied?" talk (video [RU], slides)

• Seattle.rb, 2019 "A Denial!" talk (slides)

• RailsConf, 2018 "Access Denied" talk (video, slides)

Integrations

• GraphQL Ruby (action_policy-graphql)
• Graphiti (JSON:API) (action_policy-graphiti)

Installation

Add this line to your application's Gemfile:

gem "action_policy"

And then execute:

bundle install

Usage

Action Policy relies on resource-specific policy classes (just like Pundit).

First, add an application-specific ApplicationPolicy with some global configuration to inherit from:

class ApplicationPolicy < ActionPolicy::Base
end

This may be done with rails generate action_policy:install generator.

Then write a policy for a resource. For example:

class PostPolicy < ApplicationPolicy
  # everyone can see any post
  def show?
    true
  end

  def update?
    # `user` is a performing subject,
    # `record` is a target object (post we want to update)
    user.admin? || (user.id == record.user_id)
  end
end

This may be done with rails generate action_policy:policy Post generator. You can also use rails generate action_policy:policy Post --parent=BasePolicy to make the generated policy inherits from BasePolicy.

Now you can easily add authorization to your Rails* controller:

class PostsController < ApplicationController
  def update
    @post = Post.find(params[:id])
    authorize! @post

    if @post.update(post_params)
      redirect_to @post
    else
      render :edit
    end
  end
end

* See Non-Rails Usage on how to add authorize! to any Ruby project.

When authorization is successful (i.e., the corresponding rule returns true), nothing happens, but in case of authorization failure ActionPolicy::Unauthorized error is raised.

There is also an allowed_to? method which returns true or false, and could be used, in views, for example:

<% @posts.each do |post| %>
  <li><%= post.title %>
    <% if allowed_to?(:edit?, post) %>
      <%= link_to post, "Edit">
    <% end %>
  </li>
<% end %>

Read more in our Documentation.

Alternatives

There are many authorization libraries for Ruby/Rails applications.

What makes Action Policy different? See this section in our docs.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/palkan/action_policy.

License

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