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  1. Hadoop YARN
  2. YARN-4112

YARN HA secondary-RM/NM redirect not parseable by Ambari/curl in a Kerberoized deployment

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    Details

    • Type: Bug
    • Status: Open
    • Priority: Minor
    • Resolution: Unresolved
    • Affects Version/s: 2.6.0
    • Fix Version/s: None
    • Labels:
      None

      Description

      The secondary-RM-to-primary-RM (and NM) redirect issued by YARN in a kerberoized cluster is not a proper (http-location-301-style) redirect, thus Ambari - which uses curl - does not find the "right" node. This, in turn, is triggering alerts in Ambari.

      A network dump of the ambari poll against the secondary RM looks like:

      Request:
      """
      GET /jmx?qry=Hadoop:service=ResourceManager,name=RMNMInfo HTTP/1.1
      ...
      """

      Response:
      """
      HTTP/1.1 200 OK
      ...
      Refresh: 3; url=http://

      {my-primary-rm}:8088/jmx
      Content-Length: 106
      Server: Jetty(6.1.26.hwx)

      This is standby RM. Redirecting to the current active RM:
      http://{my-primary-rm}

      :8088/jmx
      """

      Comment from Jonathan Hurley jhurley@hortonworks.com -

      This is caused by how YARN does HA mode. With two YARN RMs, the standby RM returns a 200 response with a JavaScript redirect instead of an 3xx redirection. When not using Kerberos, Ambari should be able to parse the headers and follow the JS-based redirect. However, on a Kerberized cluster, we use curl which cannot do this. Therefore, requests against the secondary RM will return an UNKNOWN response since it did get a 200. I think a few things can be improved here:

      1) There should be a ticket filed for YARN to have their HA mode use a proper redirect
      2) Ambari might not want to produce an UNKNOWN response here since it gives a false feeling that something went wrong.

      I've also filed AMBARI-12995 with the ambari team.

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              • Assignee:
                Unassigned
                Reporter:
                arobertson Andrew Robertson
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                Dates

                • Created:
                  Updated: