Following sample code shows how Rails integrates with Microsoft Active Directory using net-ldap gem.

Active Directory Environment: Windows Server 2012 R2

Development Environment: CentOS 7.5

Rails Version: 5.2.0

Create a Rails application

rails new ldap_example

Since I use PostgreSQL instead of sqlite3, I got following error:

An error occurred while installing sqlite3 (1.3.13), and Bundler cannot continue.
Make sure that `gem install sqlite3 -v '1.3.13'` succeeds before bundling.

Therefore, I use –with-pg-config option to use PostgreSQL.

rails new ldap_example --skip-spring --skip-turbolinks --skip-test-unit  --with-pg-config=/usr/bin/pg_config --database=postgresql

Add net-ldap to the Gemfile

# Net::LDAP 
gem 'net-ldap'

Install net-ldap

bundle install

Create a controller

rails generate controller sessions

Connect to your AD

class SessionsController < ApplicationController
  def login
    ldap = Net::LDAP.new  :host => '10.1.33.16',
          :port => '389',
          :auth => {
            :method => :simple,
            :username => "cywang@mydomain.com",
            :password => "tEsTpAsSwOrD1234"
          }

    if ldap.bind
      render json: {'Result': 'Login Succeeded!'}, status: status
    else
      render json: {'Result': 'Login failed'}, status: status
    end
  end
end

You can simply change the password or username to test your login method.