Ruby on Rails Advent Calendar 21日目の記事です。 DeviseとOmniauthを使って認証管理をしてみます。 Deviseとは何か Devise is a flexible authentication solution for Rails based on Warden. It: - Is Rack based; - Is a complete MVC solution based on Rails engines; - Allows you to have multiple models signed in at the same time; - Is based on a modularity concept: use just what you really need. とGithubにあるように、 WardenをベースとしたRails向けフレキシ