Bug 1330486 - Get unexpected warning inside diag container when running in healthy GCE environment
Summary: Get unexpected warning inside diag container when running in healthy GCE envi...
Keywords:
Status: CLOSED DEFERRED
Alias: None
Product: OpenShift Container Platform
Classification: Red Hat
Component: oc
Version: 3.2.0
Hardware: Unspecified
OS: Unspecified
low
low
Target Milestone: ---
: ---
Assignee: Luke Meyer
QA Contact: Wei Sun
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2016-04-26 10:56 UTC by Xia Zhao
Modified: 2019-11-21 12:56 UTC (History)
3 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2019-11-21 12:56:09 UTC
Target Upstream Version:


Attachments (Terms of Use)
Packet trace of DNS queries and responses (1.14 KB, application/octet-stream)
2016-05-03 16:41 UTC, Luke Meyer
no flags Details

Comment 1 Luke Meyer 2016-04-26 16:58:37 UTC
This error arises here: https://github.com/openshift/origin/blob/bc1ddaa85a591d2c5d1c335f17f437be8a3d2841/pkg/diagnostics/pod/dns.go#L124

This diagnostic looks through /etc/resolv.conf and checks every domain against every nameserver to see if any resolve wildcard entries (which causes big problems for DNS usage). It does so by making up an improbable hostname in the domain, e.g. "wildcard.bc1ddaa85a591d2c5d1c.svc.cluster.local" and seeing if it resolves. It shouldn't.

This error is telling you that for the given nameserver and hostname, it got back bad data. This nameserver IP doesn't sound like the skydns IP so my guess is it's one of the other nameservers in /etc/resolv.conf. Can you test directly with `dig wildcard.bc1ddaa85a591d2c5d1c.svc.cluster.local @<IP>` and see if it comes back without error?

If dig has no issue with the server, then it's possible it's a DNS library bug - this has come up before e.g. https://github.com/miekg/dns/issues/234 - in which case we would need a packet trace and any information you might have about the DNS server to try to track down the problem.

Comment 5 Xia Zhao 2016-04-28 09:55:58 UTC
My GCE env was gone and I'm trying to install new ones for the bug verification. Will update you later.

Comment 8 Luke Meyer 2016-05-03 16:41:45 UTC
Created attachment 1153514 [details]
Packet trace of DNS queries and responses

Packet trace of DNS queries and responses. I don't know which response the library didn't like, though "the last one" is probably a good guess.

Comment 9 Xia Zhao 2016-05-04 04:44:29 UTC
@lmeyer Thanks for the follow-up. Yes, I did the dig command from master machine, when I run it on the node machine, it responded fine. Thank you for pointing out this.I'm closing my env on GCE.

Comment 11 Stephen Cuppett 2019-11-21 12:56:09 UTC
OCP 3.6-3.10 is no longer on full support [1]. Marking un-triaged bugs CLOSED DEFERRED. If you have a customer case with a support exception or have reproduced on 3.11+, please reopen and include those details. When reopening, please set the Version to the appropriate version where reproduced.

[1]: https://access.redhat.com/support/policy/updates/openshift


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