Backup and incremental load could fail in secure clusters

HBase Backup and incremental load uses HConstants.DEFAULT_TEMPORARY_HDFS_DIRECTORY for temporary path.

HConstants.DEFAULT_TEMPORARY_HDFS_DIRECTORY uses the Java runtime user name to generate a temporary path on HDFS. This can be a wrong assumption in a secure cluster where Kerberos principal name can be different from the system user name.

public static final String DEFAULT_TEMPORARY_HDFS_DIRECTORY = "/user/"
      + System.getProperty("user.name") + "/hbase-staging";

This constant variable is used in BackupUtils.java and HFileOutputFormat2.java

In such cases, you will not be able to write files to the temporary location on HDFS due to permission error, and therefore operations such as backup will fail.

This bug is similar in nature to HDFS-12485.