single session devise

Devise - Invalidate user session if the same user logs in from a different browser/machine
#cmd: rails g migration add_sign_in_token_to_users
#db/migration/######_add_sign_in_token_to_users.rb
class AddSignInTokenToUsers < ActiveRecord::Migration
  def change
    add_column :users, :current_sign_in_token, :string
  end
end

#app/application_controller.rb
class ApplicationController < ActionController::Base
  before_action :invalidate_simultaneous_user_session, :unless => Proc.new {|c| c.controller_name == 'sessions' and c.action_name = 'create' }

  def invalidate_simultaneous_user_session
    sign_out_and_redirect(current_user) if current_user && session[:sign_in_token] != current_user.current_sign_in_token
  end

end

#config/application.rb
module Yourapp
  class Application < Rails::Application


  #add this
    Warden::Manager.after_authentication do |user, auth, opts|
      #auth.cookies - to access cookie
      token = Devise.friendly_token
      user.update_attribute :current_sign_in_token, token
      #session
      auth.env['rack.session'][:sign_in_token] = token
    end

    Warden::Manager.before_logout do |user, auth, opts|
      auth.env['rack.session'].delete :sign_in_token
    end
  end

end