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• Impersonation allows CDAP to launch CDAP programs, hive queries as the user (configured at the namespace level). The user principal and keytabURI can be provided when creating the namespace
• Keytab file should be put in HDFS or in the local filesystem on the master node and at the minimum, 'cdap' user should be able to read that file.
• When impersonation is used all the operations related to that namespace, such as - namespace creation (including custom mapping), program run, hive query, hbase table read/write/create/delete, hdfs directory create/read/write are all performed as that user.
• Since hdfs root directory creation happens by default under the /cdap/namespaces directory, impersonation will not work unless i) custom mapping for hdfs is set and RWX permissions are set for that user on that directory or ii) the user has RWX permissions for the /cdap/namespaces directory. Option i) is recommended!
• If authorization is also enabled, when the programs (such as flows, mapreduce) try to create/read/write datasets, permissions authorization permission for that user is checked to make sure they have the sufficient privileges to do such operations. This also applies when dataset in other namespaces are accessed (the impersonated user should have sufficient access to access dataasets in the other namespace).
  
  

Setting up a namespace, with impersonation, hbase-mapping and file system-mapping

Note: Hive impersonation is not yet complete. All Hive (Explore) operations are still done as the cdap user.

To set up a namespace with impersonation configured, an hbase namesace mapping, and a file system mapping, make an HTTP request to create namespace :as below.
Note that the configured "root.directory" must be an existing directory (on HDFS, if running distributed CDAP) and "hbase.namespace" must also be a pre-existing HBase namespace.

PUT <HostAndPort>/v3/namespaces/<namespace-id>
with the following body. Make sure to replace <namespace-id>the attributes within <>, <principal>,such and <path-to-keytab-file>as <principal>.
{"name":"<namespace-id>","description":"<namespace description>","config":{"principal":"<principal>","keytabURI":"<path-to-keytab-file>", "root.directory":"<file-system-dir>", "hbase.namespace":"<hbase-namespace>"}}

As an example (using curl):

curl -v -X PUT <HostAndPort>/v3/namespaces/foo -d '{"name":"foo","description":"My foo namespace","config":{"principal":"<PRINCIPAL>","keytabURI":"<KEYTAB_TOKEN>", "root.directory":"/tmp/foo", "hbase.namespace":"foo_ns"}}' -H "Authorization: Bearer <TOKEN>"

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