Rails 4.0.0.beta1でdevise

とりあえず、gemが対応されるまでこれで凌ごうかと。

1. Gemfile

gem 'devise', github: 'plataformatec/devise', branch: 'rails4'

2. エラー... orz

`attr_accessible': `attr_accessible` is extracted out of Rails into a gem.
 Please use new recommended protection model for params(strong_parameters) or
 add `protected_attributes` to your Gemfile to use old one. (RuntimeError)
    from /home/leapfrog/projects/kathloc/app/models/user.rb:8:in `<class:User>'

3. config/initializers/devise.rb に以下を追加

DeviseController.class_eval do
  before_action :resource_params #, only: [:show, :edit, :update, :destroy]

  def resource_params
    unless params[resource_name].blank?
      params.require(resource_name).permit(:email, :password, 
        :password_confirmation, :remember_me, :reset_password_token,
        :current_password)
    end
  end
end

Source: Rails 4 Authentication - Stack Overflow