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https://issues.apache.org/jira/browse/HDFS-6717?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14076928#comment-14076928
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Brandon Li commented on HDFS-6717:
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[~dscheffy], you are right that root group needs to be added to the the value
of hadoop.proxyuser.nfsserver.groups. The change in the patch was focusing on
answering "who is proxy user, who should start NFS gateway" and etc.
Based on your last comment, I think we should also add some description saying
"group "root" should be added to hadoop.proxyuser.nfsserver.groups in most
Linux platforms where root privilege is by default required to mount NFS
exports".
Please let me know if there is any unclear description in the doc and I will
fix it.
> 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: Sub-task
> Components: nfs
> Affects Versions: 2.4.0
> Reporter: Jeff Hansen
> Assignee: Brandon Li
> Priority: Minor
> Fix For: 2.5.0
>
> Attachments: HDFS-6717.001.patch, HdfsNfsGateway.html
>
>
> 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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