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From "Daryn Sharp (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-2764) Fix renewal of dfs delegation tokens
Date Tue, 02 Aug 2011 01:18:27 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2764?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13075991#comment-13075991
] 

Daryn Sharp commented on MAPREDUCE-2764:
----------------------------------------

The renewal problem can be solved far more easily, w/o false coupling, and w/o an assumption
that hftp uses https.  A DFS issues and renews tokens.  The problem is the lack of traceability
from a token to its origin DFS.  Setting a DFS DT's service field to be the DFS uri, instead
of ip:port, will allow a trivial {{FileSystem.get}} to obtain the DFS.  All guessing is removed,
and the hftp fs encapsulates that it's using https.

The RPC layer and the token selectors will require minor modification to use the authority
of the uri in the service field.  The semantics of other tokens should not be affected.

> Fix renewal of dfs delegation tokens
> ------------------------------------
>
>                 Key: MAPREDUCE-2764
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2764
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>             Fix For: 0.20.205.0
>
>
> The JT may have issues renewing hftp tokens which disrupt long distcp jobs.  The problem
is the JT's delegation token renewal code is built on brittle assumptions.  The token's service
field contains only the "ip:port" pair.  The renewal process assumes that the scheme must
be hdfs.  If that fails due to a {{VersionMismatchException}}, it tries https based on another
assumption that it must be hftp if it's not hdfs.  A number of other exceptions, most commonly
{{IOExceptions}}, can be generated which fouls up the renewal since it won't fallback to https.

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