[
https://issues.apache.org/jira/browse/MAPREDUCE-3825?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13205882#comment-13205882
]
Daryn Sharp commented on MAPREDUCE-3825:
----------------------------------------
I think requiring every filesystem to bracket its token retrieval with
identical "check for my token" and "set my token" is brittle. It's an invasive
change that isn't backwards compatible, so any filesystem that doesn't properly
do a copy-n-paste will cause duplicate tokens. If we want to universally
change the behavior, we have to change the filesystems again.
I feel it's much safer for a filesystem to implement primitives that a common
method uses. My proposed FileSystem#getDelegationTokens does just that. All a
filesystem has to do is implement getDelegationToken & maybe getFileSystems if
it has multiple tokens. Everything else is managed for the filesystem. I'd
like to make FileSystem#getDelegationsTokens a final method to enforce the
consistency and prevent any filesystem from trying to directly manipulate the
credentials. If we want to change the implementation in the future, there's
only one place, in our control, that needs to be changed.
The sample code also prevents viewfs from shorting out on calls to the same
filesystem. It can't be solved by uniquing the fs list. Otherwise, it's a
repeat of the TokenCache 1-to-1 mapping of service to a specific token problem.
We can't avoid this by uniquing the fs list in viewfs because the underlying
mounts might have multiple filesystems, or it might be returning a null service
(filtered) yet have a contained filesystem with a token.
Once MAPREDUCE-3849 is incorporated, I can fix TokenCache to eliminate the
1-to-1 mapping problem by simply calling getDelegationTokens on the filesystems.
> Need generalized multi-token filesystem support
> -----------------------------------------------
>
> Key: MAPREDUCE-3825
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-3825
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: security
> Affects Versions: 0.23.1, 0.24.0
> Reporter: Daryn Sharp
> Assignee: Daryn Sharp
> Attachments: MAPREDUCE-3825.patch, TokenCache.pdf
>
>
> This is the counterpart to HADOOP-7967. The token cache currently tries to
> assume a filesystem's token service key. The assumption generally worked
> while there was a one to one mapping of filesystem to token. With the advent
> of multi-token filesystems like viewfs, the token cache will try to use a
> service key (ie. for viewfs) that will never exist (because it really gets
> the mounted fs tokens).
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
