在 Gemfile 中为 OmniAuth 添加 Gems

gem 'omniauth-oauth2' , '~> 1.3.1'
gem 'omniauth'
gem 'omniauth-facebook'
gem 'omniauth-twitter'
gem 'omniauth-gplus'
gem 'omniauth-linkedin'

运行 bundle install 命令，重新启动服务器然后离开！