2.1. Configuration Overview

Creating a mapping between service principals and UNIX usernames.

Hadoop uses group memberships of users at various places, such as to determine group ownership for files or for access control.

A user is mapped to the groups it belongs to using an implementation of the GroupMappingServiceProvider interface. The implementation is pluggable and is configured in core-site.xml.

By default Hadoop uses ShellBasedUnixGroupsMapping, which is an implementation of GroupMappingServiceProvider. It fetches the group membership for a username by executing a UNIX shell command. In secure clusters, since the usernames are actually Kerberos principals, ShellBasedUnixGroupsMapping will work only if the Kerberos principals map to valid UNIX usernames. Hadoop provides a feature that lets administrators specify mapping rules to map a Kerberos principal to a local UNIX username .

Adding information to three main service configuration files.

There are several optional entries in the three main service configuration files that must be added to enable security on HDP.