Jeff Hansen created HDFS-6717:
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Summary: Jira HDFS-5804 breaks default nfs-gateway behavior for
unsecured config
Key: HDFS-6717
URL: https://issues.apache.org/jira/browse/HDFS-6717
Project: Hadoop HDFS
Issue Type: Bug
Components: nfs
Affects Versions: 2.4.0
Reporter: Jeff Hansen
Priority: Minor
I believe this is just a matter of needing to update documentation. As a result
of https://issues.apache.org/jira/browse/HDFS-5804, the secure and unsecure
code paths appear to have been merged -- this is great because it means less
code to test. However, it means that the default unsecure behavior requires
additional configuration that needs to be documented.
I'm not the first to have trouble following the instructions documented in
http://hadoop.apache.org/docs/r2.4.0/hadoop-project-dist/hadoop-hdfs/HdfsNfsGateway.html
I kept hitting a RemoteException with the message that hdfs user cannot
impersonate root -- apparently under the old code, there was no impersonation
going on, so the nfs3 service could and should be run under the same user id
that runs hadoop (I assumed this meant the user id "hdfs"). However, with the
new unified code path, that would require hdfs to be able to impersonate root
(because root is always the local user that mounts a drive). The comments in
jira hdfs-5804 seem to indicate nobody has a problem with requiring the
nfsserver user to impersonate root -- if that means it's necessary for the
configuration to include root as a user nfsserver can impersonate, that should
be included in the setup instructions.
More to the point, it appears to be absolutely necessary now to provision a
user named "nfsserver" in order to be able to give that nfsserver ability to
impersonate other users. Alternatively I think we'd need to configure hdfs to
be able to proxy other users. I'm not really sure what the best practice should
be, but it should be documented since it wasn't needed in the past.
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