omniauth strategy

app/controllers/application_controller.rb

@@ -1,3 +1,8 @@
 class ApplicationController < ActionController::Base
   protect_from_forgery with: :exception
+
+  def current_user
+    @current_user ||= User.find_by(id: session[:user_id])
+  end
+  helper_method :current_user
 end

app/controllers/sessions_controller.rb

@@ -0,0 +1,17 @@
+class SessionsController < ApplicationController
+  def create
+    @user = User.from_omniauth(request.env['omniauth.auth'])
+    session[:user_id] = @user.id
+  rescue => e
+    logger.error "Error authenticating via omniauth: #{e}"
+  ensure
+    redirect_to root_path
+  end
+
+  def destroy
+    if current_user
+      session.delete(:user_id)
+    end
+    redirect_to root_path
+  end
+end