Hadoop Impersonation Prerequisites

Transformer can impersonate a Hadoop user defined in the pipeline to launch the Spark application and to access services in the Hadoop system. To do this, you configure the Hadoop User Name property on the Cluster tab of the pipeline properties.

To enable impersonating a Hadoop user defined in the pipeline, you must complete some prerequisite tasks on the MapR cluster. When impersonating the user who starts the pipeline, these tasks are unnecessary.

The tasks to perform differ depending on whether the cluster is secured.

Secure clusters

A secure cluster requires username-password or Kerberos authentication. Complete the following tasks to enable impersonating a Hadoop user defined in a pipeline:

Generate impersonation tickets.
Create impersonation tickets on the MapR node where Transformer is installed. When you create the tickets, you specify the location to store them.
Set the MAPR_TICKET_LOCATION environment variable.
On the MapR node where Transformer is installed, set the MAPR_TICKET_LOCATION environment variable to the location where the impersonation tickets are stored.
For example:
```
export MAPR_TICKET_LOCATION=/var/tmp/imp-tickets
```

For details on performing these tasks, see the MapR documentation.

Non-secure clusters

A non-secure cluster does not require authentication for access. Complete the following tasks to enable impersonating a Hadoop user defined in a pipeline:

Set the MAPR_IMPERSONATION_ENABLED environment variable.
On the MapR node where Transformer is installed, set the MAPR_TICKET_LOCATION environment variable to true.
Create a proxy file.
Create a proxy file in the following location:
```
/opt/mapr/conf/proxy/
```

For details on performing these tasks, see the MapR documentation.