applicationController.rb

class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception


  private 
  def current_user
  	@current_user ||= User.find(session[:user_id]) if session[:user_id]
  end

  def require_login
  	if session[:user_id] == nil
  		redirect_to root_path
  	end
  end


  helper_method :require_login
  helper_method :current_user
  
end

home.html.erb

<nav class="navbar navbar-default">
	<div class="container-fluid">
		
	</div>


	<div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
		<ul class="nav navbar-nav navbar-right">
			<% if current_user %>
				<li>signed in as: <%= current_user.name %> - <%= image_tag(@auth['info']['image'],width: '50',height:'50', class:'img-circle') %> </li>
				<li><%= link_to "Sign Out", 'sign_out', method: :delete %> </li>
			<% else %>

				<li><%= link_to "auth/facebook" do %><%=image_tag('facebook.png',width: '40',height:'40', class:'img-circle') %> <% end %> </li>


			<% end %>

		</ul>




	</div>
</nav>

homeController.rb

class HomeController < ApplicationController
	before_action :set_auth
	
	def index
	end

	def profile
	end

    private 
    def set_auth
 	  	@auth=session[:omniauth] if session[:omniauth]
	end
end

routes.rb

Rails.application.routes.draw do
  root 'home#index'

  get 'home/profile'

  get   'auth/:provider/callback', to: "sessions#create"
  delete 'sign_out', to: "sessions#destroy", as: "sign_out"
  
end

SessionsController.rb

class SessionsController < ApplicationController
	def create
		auth = request.env["omniauth.auth"]
		session[:omniauth] = auth.except('extra')
		user = User.sign_in_from_omniauth(auth)
		session[:user_id] = user.id
		redirect_to root_url, notice: "Signed In"
	end

	def destroy
		session.delete(:user_id)
		session.delete(:omniauth)
		redirect_to root_url, notice: "Signed Out"
	end

end