[YARN-4112] YARN HA secondary-RM/NM redirect not parseable by Ambari/curl in a Kerberoized deployment

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.6.0
• Component/s: nodemanager, resourcemanager
• Assignee: Unassigned
• Reporter: Andrew Robertson
• Created: 03/Sep/15 13:53
• Updated: 16/Sep/15 19:16

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 [e-mail] -
—
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.

Issue Links

• duplicates: YARN-2605 [RM HA] Rest api endpoints doing redirect incorrectly
• relates to: AMBARI-12995 Ambari alerts reports "UNKNOWN" error for secondary YARN RM and NM in a kerberoized YARN HA deployment