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From "Yongjun Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-7146) NFS ID/Group lookup requires SSSD enumeration on the server
Date Wed, 01 Oct 2014 02:00:40 GMT

    [ https://issues.apache.org/jira/browse/HDFS-7146?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14154223#comment-14154223

Yongjun Zhang commented on HDFS-7146:

HI [~brandonli],

Thanks a lot for the review and comments!

I think you made a very good point. One problem I found when doing the test is, for numerical
user name, "getent passwd <username>" would return nothing, however, the initial initialization
code will catch it correctly. So looks like we can't totally take the initialization out.
 That said, keeping the initialization part would help this issue I described, but may not
completely fix it because of the issue reported by this jira (i.e., the initial list may not
be complete). 

What about we keep the initialization part for now, and decide whether we can drop it later?
This way, the impact of this jira fix is minimized: all stuff that worked should continue
to work, and the issue reported by this jira will be fixed by the change?

Thanks again.

> NFS ID/Group lookup requires SSSD enumeration on the server
> -----------------------------------------------------------
>                 Key: HDFS-7146
>                 URL: https://issues.apache.org/jira/browse/HDFS-7146
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: nfs
>    Affects Versions: 2.6.0
>            Reporter: Yongjun Zhang
>            Assignee: Yongjun Zhang
>         Attachments: HDFS-7146.001.patch
> The current implementation of the NFS UID and GID lookup works by running 'getent passwd'
with an assumption that it will return the entire list of users available on the OS, local
and remote (AD/etc.).
> This behaviour of the command is advised to be and is prevented by administrators in
most secure setups to avoid excessive load to the ADs involved, as the # of users to be listed
may be too large, and the repeated requests of ALL users not present in the cache would be
too much for the AD infrastructure to bear.
> The NFS server should likely do lookups based on a specific UID request, via 'getent
passwd <UID>', if the UID does not match a cached value. This reduces load on the LDAP
backed infrastructure.
> Thanks [~qwertymaniac] for reporting the issue.

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