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https://issues.apache.org/jira/browse/YARN-4234?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15001455#comment-15001455
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Naganarasimha G R commented on YARN-4234:
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Hi [~jlowe] & [~gtCarrera], 
AFAIK, YARN-4183 wanted to address lil more than that what is captured by 
[~gtCarrera] (related to whether client should fail when timelineserver is not 
reachable....).
But what i dont understand(or missing), as per the current code (ATSv1) is,  
only if the *"yarn.timeline-service.enabled"* is enabled only then the 
delegation tokens are created automatically in the YARNClientImpl. So not sure 
why [~jeagles] was pointing out all apps were trying to get delegation tokens 
in YARN-4183. I understand  SystemMetric Publisher (Server) need not check for 
this configuration but not sure why client should depend on some server side 
configuration?
Additionally we already have client side configuration 
*"yarn.timeline-service.client.best-effort"*  (realized it now) if when 
configured will not fail the {{YARNClient.SubmitApplication}} if fail to get 
the delegation tokens.

Hope My understanding about the problem is correct, If correct then as part of 
YARN-4183 we need to just remove the check for 
*"yarn.timeline-service.enabled"* being used in SystemMetricsPublisher, Please 
correct me if i am wrong.

And coming to this patch(support for 1.5) i can envisage it as follows:
* Server will be configured with *"TIMELINE_SERVICE_VERSION"* based on which 
appropriate timeline handler is selected
* Client apps who ever want to communicate with Timeline server will enable  
*"yarn.timeline-service.enabled"* 
* If security and *"yarn.timeline-service.enabled"*  are enabled then 
delegation token is got in the yarn client as earlier
* when the timeline client is intitialized it contacts server for the version 
and related configs and once it receives it initializes itself.
* If user tries to use invalid methods (not appropriate to the server timeline 
version) then timelineclient throws exception

Thoughts ?

> New put APIs in TimelineClient for ats v1.5
> -------------------------------------------
>
>                 Key: YARN-4234
>                 URL: https://issues.apache.org/jira/browse/YARN-4234
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>          Components: timelineserver
>            Reporter: Xuan Gong
>            Assignee: Xuan Gong
>         Attachments: YARN-4234-20151111.2.patch, YARN-4234.1.patch, 
> YARN-4234.2.patch, YARN-4234.20151109.patch, YARN-4234.20151110.1.patch, 
> YARN-4234.20151111.1.patch, YARN-4234.3.patch
>
>
> In this ticket, we will add new put APIs in timelineClient to let 
> clients/applications have the option to use ATS v1.5



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