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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 Mon, 06 Oct 2014 18:35:35 GMT

    [ https://issues.apache.org/jira/browse/HDFS-7146?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14160659#comment-14160659

Yongjun Zhang commented on HDFS-7146:

HI [~brandonli], thanks for your comments. I just uploaded rev 03. It works slightly different
than what you described.

1. At initialization, the map is empty
2. Both users/groups/ids are added to the map on demand (e.g. when requested), 
3. When groupId is requested for a given groupName, if the groupName is numerical, the full
group map is loaded (this is lazy full list load I referred to ealier
4. Periodically update the cached maps for both user and group. What I do here is actually
to clear the map. I imaged that some users and groups might be removed (for example, a user
changed job), so I instead of loading anything, I cleared the map during this update, essentially
reinitialize the map. And then steps 2 and 3 will be repeated

I did not change the logic when to update the map.

Would you please take a look again to see if the change makes sense to you? thanks a lot.

> 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, HDFS-7146.002.allIncremental.patch, HDFS-7146.003.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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