Configuring LDAP Group Mappings

Each host that comprises a node in a Cloudera cluster runs an operating system, such as CentOS or Oracle Linux. At the OS-level, there are user:group accounts created during installation that map to the services running on that specific node of the cluster. The default shell-based group mapping provider, org.apache.hadoop.security.ShellBasedUnixGroupsMapping, handles the mapping from the local host system (the OS) to the specific cluster service, such as HDFS. The hosts authenticate using these local OS accounts before processes are allowed to run on the node.

For clusters integrated with Kerberos for authentication, the hosts must also provide Kerberos tickets before processes can run on the node. The cluster can use the organization's LDAP directory service to provide the login credentials, including Kerberos tickets, to authenticate transparently while the system runs. That means that the local user:group accounts on each host must be mapped to LDAP accounts. To map local user:group accounts to an LDAP service:

Use tools such as SSSD (Systems Security Services Daemon) or Centrify Server Suite (see Identity and Access management for Cloudera).
The Hadoop LdapGroupsMapping group mapping mechanism. The LdapGroupsMapping library may not be as robust a solution needed for large organizations in terms of scalability and manageability, especially for organizations managing identity across multiple systems and not exclusively for Hadoop clusters. Support for the LdapGroupsMapping library is not consistent across all operating systems.
Do not use Winbind to map Linux user:group accounts to Active Directory. It cannot scale, impedes cluster performance, and is not supported.
Use the same user:group mappings across all cluster nodes, for ease of management.
Use either Cloudera Manager or the command-line process detailed below.

The local user:group accounts must be mapped to LDAP for group mappings in Hadoop. You must create the users and groups for your Hadoop services in LDAP.

To integrate the cluster with an LDAP service, the user:group relationships must be contained in the LDAP directory. The admin must create the user accounts and define groups for user:group relationships on each host.

The user and group names listed in the table are the default user:group values for CDP services.


Cloudera Product or Component	User	Group
Cloudera Manager	`cloudera-scm`	`cloudera-scm`
Apache Accumulo	`accumulo`	`accumulo`
Apache Avro	(No default)	(No default)
Apache HBase (Master, RegionServer processes)	`hbase`	`hbase`
Apache HCatalog	`hive`	`hive`
Apache Hive (HiveServer2, Hive Metastore)	`hive`	`hive`
Apache Kafka	`kafka`	`kafka`
Apache Oozie	`oozie`	`oozie`
Apache Spark	`spark`	`spark`
Apache Sqoop1	`sqoop`	`sqoop`
Apache Whirr	(No default)	(No default)
Apache ZooKeeper	`zookeeper`	`zookeeper`
Impala	`impala`	`impala, hive`
Cloudera Search	`solr`	`solr`
HDFS (NameNode, DataNodes)	`hdfs`	`hdfs, hadoop`
HttpFS	`httpfs`	`httpfs`
Hue	`hue`	`hue`
Hue Load Balancer (needs apache2 package)	`apache`	`apache`
Java KeyStore KMS	`kms`	`kms`
Key Trustee KMS	`kms`	`kms`
Key Trustee Server	`keytrustee`	`keytrustee`
Kudu	`kudu`	`kudu`
Llama	`llama`	`llama`
MapReduce (JobTracker, TaskTracker)	`mapred`	`mapred, hadoop`
Parquet	(No default)	(No default)
YARN	`yarn`	`yarn, hadoop`

Using Cloudera Manager

Minimum Required Role: Configurator (also provided by Cluster Administrator, Limited Cluster Administrator , and Full Administrator)

Make the following changes to the HDFS service's security configuration:

Open the Cloudera Manager Admin Console and go to the HDFS service.
Click the Configuration tab.
Select Scope > HDFS (Service Wide)
Select Category > Security.

Modify the following configuration properties using values from the table below:


Configuration Property	Value
Hadoop User Group Mapping Implementation	`org.apache.hadoop.security.LdapGroupsMapping`
Hadoop User Group Mapping LDAP URL	`ldap://<server>`
Hadoop User Group Mapping LDAP Bind User	`Administrator@example.com`
Hadoop User Group Mapping LDAP Bind User Password	`***`
Hadoop User Group Mapping Search Base	`dc=example,dc=com`

Although the above changes are sufficient to configure group mappings for Active Directory, some changes to the remaining default configurations might be required for OpenLDAP.

Emitting the LDAP Bind password in core-site.xml for client configurations

If the CDP cluster has LDAP group to OS group mapping enabled, then applications running in Spark or Yarn would fail to authenticate to the LDAP server when trying to use the LDAP bind account during the LDAP group search. This is because the LDAP bind password was not passed to the /etc/hadoop/conf/core-site.xml file. This was intended behavior to prevent leaking the LDAP bind password in a clear text field.

Starting with Cloudera Manager 7.7.1 CHF 17 and Cloudera Manager 7.11.3 CHF 2, the cluster administrator can enable Cloudera Manager to pass the LDAP bind password to client applications in clear text through the /etc/hadoop/conf/core-site.xml file.

To do this, modify the Cloudera Manager server configuration file /etc/default/cloudera-scm-server by adding the flag -Dcom.cloudera.cmf.service.config.emitLdapBindPasswordInClientConfig=true to the variable CMF_JAVA_OPTS flag such as:
```
CMF_JAVA_OPTS="-Xmx4G -XX:+HeapDumpOnOutOfMemoryError
-XX:HeapDumpPath=/tmp
-Dcom.sun.management.jmxremote.ssl.enabled.protocols=TLSv1.2
-Dcom.cloudera.cmf.service.config.emitLdapBindPasswordInClientConfig=true"
```
important
The previous contents of the CMF_JAVA_OPTS variable might be slightly different than the example above, but those contents should be preserved.
To have the setting take effect, restart the Cloudera Manager server by running the following command:
```
sudo systemctl restart cloudera-scm-server
```
Then deploy client configuration files to have Cloudera Manager redistribute the Hadoop core-site.xml client configuration file. See Manually Redeploying Client Configuration Files.