[jira] [Commented] (HADOOP-7214) Hadoop /usr/bin/groups equivalent

["Aaron T. Myers (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-7214?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13014888#comment-13014888 ] 

Aaron T. Myers commented on HADOOP-7214:
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I did a little digging into this and the ideal implementation is not as obvious to me as I anticipated. Here's a few ideas:

# Given that both the NN and the JT do user -> group resolution, it'd be nice to implement this in a way common to both of them. This suggests creating a new protocol common to both just for this purpose, and adding a new option to {{`hadoop'}} along the lines of {{`hadoop groups <host:port> [username...]'}}.
\\
# The hadoop filesystem client {{i.e. `hadoop fs'}} already has commands which assume the existence of groups (e.g. `hadoop fs -chgrp'.) It therefore seems natural to implement this as a new method in FileSystem and to add a new option to {{`hadoop fs'}} along the lines of {{`hadoop fs -groups <host:port> [username...]'}}. This also seems natural since most file system implementations already deal with groups and have an obvious way of performing user -> group mapping.
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# We could implement this as just a servlet, along the lines of {{`hadoop daemonlog'}}.

Option #1 seems like it might be a little too heavyweight for this purpose. The trouble with option #2 is that there's presently no M/R analog to {{`hadoop fs'}} like, for example, {{`hadoop mr'}}. I don't actually think option #3 is a good idea at all, but I listed it here for completeness.

Any thoughts? I'm certainly open to any options not listed here.

> Hadoop /usr/bin/groups equivalent
> ---------------------------------
>
>                 Key: HADOOP-7214
>                 URL: https://issues.apache.org/jira/browse/HADOOP-7214
>             Project: Hadoop Common
>          Issue Type: New Feature
>    Affects Versions: 0.23.0
>            Reporter: Aaron T. Myers
>            Assignee: Aaron T. Myers
>
> Since user -> groups resolution is done on the NN and JT machines, there should be a way for users to determine what groups they're a member of from the NN's and JT's perspective.

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