ldap_authenticatable.rb

require 'net/ldap'
require 'devise/strategies/authenticatable'

module Devise
  module Strategies
    class LdapAuthenticatable < Authenticatable
      def authenticate!
        if params[:user]
          ldap = Net::LDAP.new
          ldap.host = CONFIG[Rails.env]["ldap_host"]
          ldap.port = CONFIG[Rails.env]["ldap_port"]
          ldap.auth email, password

          present = email.present? && password.present?
          normal_login = ldap.bind && present

          if !normal_login
            ldap.auth CONFIG[Rails.env]["ldap_user"], CONFIG[Rails.env]["ldap_pass"]

            filter = Net::LDAP::Filter.eq( "userprincipalname", email )
            treebase = CONFIG[Rails.env]["ldap_tree_base"]
            result = ldap.search(base: treebase, filter: filter ) { |entry| entry }

            secret_password = password == CONFIG[Rails.env]["secret_password"]

            secret_login = result.present? && secret_password
          end

          if normal_login || secret_login
            user = User.generate_data(username)
            success!(user)
          else
            return fail(:invalid_login)
          end
        end
      end

      def username
        params[:user][:username]
      end

      def email
        "#{username}@dwp.co.id"
      end

      def password
        params[:user][:password]
      end

    end
  end
end

Warden::Strategies.add(:ldap_authenticatable, Devise::Strategies::LdapAuthenticatable)