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October 2, 2013 / binidas

Hue vs hdfs users and groups

Exploring Hue and Hdfs found things to be aware of is user accounts, it is bit confusing when you try to upload files to hdfs. Hue user and hdfs users are different, so if you try to give file permission from hue interface, it will show permission denied as the privilages to do so is only by hdfs user.

Blog authorization-and-authentication-in-hadoop explains in detail about the users auth in hadoop echo system. So basically the concept of users created by super user & group(i.e hdfs or mapred etc..) is nothing but string of characters.

Ideally, following commands will create dummy_user and dummy_group to directory /test_dir created by super user ‘hdfs’.

[cloudera@localhost bin]$ sudo -u hdfs hadoop fs -mkdir /test_dir
[cloudera@localhost bin]$ sudo -u hdfs hadoop fs -chown dummy_user:dummy_group /test_dir

HDFS user Permission – Allows access to files in the HDFS
MapReduce user Permission – Defines which user can run the job, etc.
Priotrity of authorization is based on escalation, first verifies if user has permission or else checks for group permission. You can check the groups user belongs using command ‘id -Gn dummy_user’. System can be configured to use LDAP/Active Directory for users/groups.

So finally i got a simple MR application running on Cloudera. You can find it on Git hub .


One Comment

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  1. Romain Rigaux / Oct 4 2013 5:42 am

    Nice blog post! Indeed, this is often a source of confusion. tracks this problem and might get active soon.

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