By default, Ambari uses an internal database as the user store for authentication and authorization. To add LDAP or Active Directory (AD) or Kerberos external authentication in addition for Ambari Web, you must collect the required information and run a special setup command. Ambari Server must not be running when you execute this command.
For information on setting up LDAP or Active Directory authentication, see section 1. Optional: Set Up LDAP or Active Directory Authentication of chapter 2. Advanced Security Options for Ambari in Ambari Security Guide on Hortonworks Data Platform website.
For information on Setting Up Kerberos authentication, see chapter 1. Configuring Kerberos Authentication in Ambari Security Guide on Hortonworks Data Platform website.
For information on adding and removing users from Hadoop group, see section 7.3. Adding and Removing Users in Red Hat Gluster Storage 3.1 Installation Guide.