Usage flash on Rails and Bootstrap

index.html.erb

<% flash.each do |message_type, message| %>
  <div class="alert alert-<%= message_type %> alert-dismissible fade show" role="alert">
    <%= message %>
    <button type="button" class="close" data-dismiss="alert" aria-label="Close">
      <span aria-hidden="true">&times;</span>
    </button>
  </div>
<% end %>

pages.rb

class PagesController < ApplicationController
  def index
    flash[:success] = 'You loged in'
    redirect_to root_path
  end
end