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Bug 1614981

Summary:	[3.8] Intermittent dnsmasq outages
Product:	OpenShift Container Platform	Reporter:	Miciah Dashiel Butler Masters <mmasters>
Component:	Networking	Assignee:	Miciah Dashiel Butler Masters <mmasters>
Networking sub component:	router	QA Contact:	zhaozhanqi <zzhao>
Status:	CLOSED WONTFIX	Docs Contact:
Severity:	unspecified
Priority:	unspecified	CC:	aos-bugs, bbennett, farandac, hongli, pdwyer, rbost, rfoyle, rhowe, zzhao
Version:	3.8.0
Target Milestone:	---
Target Release:	3.8.z
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:	1600551	Environment:
Last Closed:	2018-08-13 16:25:20 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1600551
Bug Blocks:

Description Miciah Dashiel Butler Masters 2018-08-10 23:05:20 UTC

Cloned for 3.8.z backport.

+++ This bug was initially created as a clone of Bug #1600551 +++

Description of problem: Pods are experiencing intermittent DNS lookup failures when reaching out to dnsmasq. A similar upstream issue has been reported: https://github.com/kubernetes/kubernetes/issues/45976

[...]

--- Additional comment from Ryan Howe on 2018-08-09 10:28:47 EDT ---

Working another OpenShift dnsmasq issue we figured the issue to happen when dnsmasq uses a low port number. 

Setting min-port=1024 in dnsmasq worked around the issue. 

--min-port=<port>
              Do not use ports less than that given as source for outbound DNS queries. Dnsmasq picks random ports as source for outbound queries: when this option is given, the ports used will always to larger than that  specified. Useful for systems behind firewalls.


Dnsmasq bug was logged: 
  https://bugzilla.redhat.com/show_bug.cgi?id=1614331


I was not able to reproduce the issue again with this configuration in place.

--- Additional comment from Ryan Howe on 2018-08-09 11:11:26 EDT ---

Created PR to add this configuration via the ansible installer for OpenShift: 

https://github.com/openshift/openshift-ansible/pull/9505

[...]

Comment 1 Miciah Dashiel Butler Masters 2018-08-10 23:13:00 UTC

OCP 3.8.z backport: https://github.com/openshift/openshift-ansible/pull/9540

Comment 2 Miciah Dashiel Butler Masters 2018-08-13 16:25:20 UTC

Apparently we don't need the OCP 3.8.z backport.