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https://issues.apache.org/jira/browse/YARN-3021?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14275797#comment-14275797
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Anubhav Dhoot commented on YARN-3021:
-------------------------------------

Looking at the patch itself we seem to suppress an error that would earlier be 
visible to user. Thats going to make it harder to detect genuine failures. MR1 
seems to be worse than YARN in this aspect and we don't need to make it match 
that behavior. If we really need to skip validation, as you said, adding a 
feature into YARN where application could opt in would be better. 

Having said that, if RM cannot validate the token as valid why would the job 
itself work? Would not the containers themselves face the same issue using the 
tokens? 

> YARN's delegation-token handling disallows certain trust setups to operate 
> properly
> -----------------------------------------------------------------------------------
>
>                 Key: YARN-3021
>                 URL: https://issues.apache.org/jira/browse/YARN-3021
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: security
>    Affects Versions: 2.3.0
>            Reporter: Harsh J
>         Attachments: YARN-3021.patch
>
>
> Consider this scenario of 3 realms: A, B and COMMON, where A trusts COMMON, 
> and B trusts COMMON (one way trusts both), and both A and B run HDFS + YARN 
> clusters.
> Now if one logs in with a COMMON credential, and runs a job on A's YARN that 
> needs to access B's HDFS (such as a DistCp), the operation fails in the RM, 
> as it attempts a renewDelegationToken(…) synchronously during application 
> submission (to validate the managed token before it adds it to a scheduler 
> for automatic renewal). The call obviously fails cause B realm will not trust 
> A's credentials (here, the RM's principal is the renewer).
> In the 1.x JobTracker the same call is present, but it is done asynchronously 
> and once the renewal attempt failed we simply ceased to schedule any further 
> attempts of renewals, rather than fail the job immediately.
> We should change the logic such that we attempt the renewal but go easy on 
> the failure and skip the scheduling alone, rather than bubble back an error 
> to the client, failing the app submission. This way the old behaviour is 
> retained.



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