Simple Auth

SimpleAuth is an authentication library to be used when everything else is just too complicated.

This library only handles session. You have to implement the authentication strategy as you want (e.g. in-site authentication, OAuth, etc).

Installation

Just the following line to your Gemfile:

gem "simple_auth"

Then run rails generate simple_auth:install to copy the initializer file.

Usage

The initializer will install the required helper methods on your controller. So, let's say you want to support user and admin authentication. You'll need to specify the following scope.

# config/initializers/simple_auth.rb
SimpleAuth.setup do |config|
  config.scopes = %i[user admin]
  config.login_url = proc { login_path }
  config.logged_url = proc { dashboard_path }
  config.flash_message_key = :alert

  config.install_helpers!
end

Session is valid only when Controller#authorized_#{scope}? method returns true, which is the default behavior. You can override these methods with your own rules; the following example shows how you can authorize all e-mails from @example.com to access the admin dashboard.

class Admin::DashboardController < ApplicationController
  private
  def authorized_admin?
    current_user.email.match(/@example.com\z/)
  end
end

So, how do you set up a new user session? That's really simple, actually.

class SessionsController < ApplicationController
  def new
  end

  def create
    @user = User.find_by_email(params[:email])

    if @user.try(:authenticate, params[:password])
      SimpleAuth::Session.create(scope: "user", session: session, record: @user)
      redirect_to return_to(dashboard_path)
    else
      flash[:alert] = "Invalid username or password"
      render :new
    end
  end

  def destroy
    reset_session
    redirect_to root_path
  end
end

First thing to notice is that SimpleAuth doesn't care about how you authenticate. You could easily set up a different authentication strategy, e.g. API tokens. The important part is assigning the record: and scope: options. The return_to helper will give you the requested url (before the user logged in) or the default url.

SimpleAuth uses GlobalID as the session identifier. This allows using any objects that respond to #to_gid, including namespaced models and POROs.

session[:user_id]
#=> gid://myapp/User/1

If you need to locate a record using such value, you can do it by calling GlobalID::Locator.locate(session[:user_id])

Finally, only ActiveRecord::RecordNotFound errors are trapped by SimpleAuth (when ActiveRecord is available). If you locator raises a different exception, add the error class to the list of known exceptions.

SimpleAuth::Session.record_not_found_exceptions << CustomNotFoundRecordError

Logging out users

Logging out a user is just as simple; all you have to do is calling the regular reset_session.

Restricting access

You can restrict access by using 2 macros. Use redirect_logged_#{scope} to avoid rendering a page for logged user.

class SignupController < ApplicationController
  before_action :redirect_logged_user
end

Use require_logged_#{scope} to enforce authenticated access.

class DashboardController < ApplicationController
  before_action :require_logged_user
end

"So which helpers are defined?", you ask. Just three simple helpers.

#{scope}_logged_in?    # e.g. user_logged_in? (available in controller & views)
current_#{scope}       # e.g. current_user    (available in controller & views)
#{scope}_session       # e.g. user_session    (available in controller & views)

Translations

These are the translations you'll need:

en:
  simple_auth:
    user:
      need_to_be_logged_in: "You need to be logged in"
      not_authorized: "You don't have permission to access this page"

If you don't set these translations, a default message will be used.

To display the error message, use something like <%= flash[:alert] %>. If you want to use a custom key, say :error, use the configuration file config/initializers/simple_auth.rb to define the new key:

config/initializers/simple_auth.rb

SimpleAuth.setup do |config| # ...

config.flash_message_key = :error

# ... end

## Maintainer

* Nando Vieira (<http://nandovieira.com>)

## License:

(The MIT License)

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.