Bug 1880307

Summary:	[release 4.5] console-operator: Fix bug in reflector not recovering from "Too large resource version"
Product:	OpenShift Container Platform	Reporter:	Lukasz Szaszkiewicz <lszaszki>
Component:	Management Console	Assignee:	Jakub Hadvig <jhadvig>
Status:	CLOSED ERRATA	QA Contact:	Yadan Pei <yapei>
Severity:	high	Docs Contact:
Priority:	high
Version:	4.5	CC:	aos-bugs, jokerman, spadgett, yapei
Target Milestone:	---
Target Release:	4.5.z
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-10-19 14:54:26 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:	1880369
Bug Blocks:	1879901

Description Lukasz Szaszkiewicz 2020-09-18 09:29:09 UTC

A recent fix in the reflector/informer https://github.com/kubernetes/kubernetes/pull/92688 prevents components/operators from entering a hotloop and stuck.

There are already reported cases that have run into that issue and were stuck for hours or even days. For example https://bugzilla.redhat.com/show_bug.cgi?id=1877346.

The root cause of the issue is the fact that a watch cache is initialized from the global revision (etcd) and might stay on it for an undefined period (if no changes were (add, modify) made).
That means that the watch cache across server instances may be out of sync.
That might lead to a situation in which a client gets a resource version from a server that has observed a newer rv, disconnect (due to a network error) from it, and reconnect to a server that is behind, resulting in “Too large resource version“ errors.

More details in https://github.com/kubernetes/kubernetes/issues/91073 and https://github.com/kubernetes/enhancements/tree/master/keps/sig-api-machinery/1904-efficient-watch-resumption

It looks like the issue only affects 1.18. According to https://github.com/kubernetes/kubernetes/issues/91073#issuecomment-652251669 the issue was first introduced in that version by changes done to the reflector.
The fix is already present in 1.19.

Please make sure that console-operator is using a client-go that includes https://github.com/kubernetes/kubernetes/pull/92688 if not please use this BZ and file a PR.
In case you are using a framework to build your operator make sure it uses the right version of the client-go library.

Comment 4 Yadan Pei 2020-10-12 03:17:22 UTC

1. disconnected a node from network for a few minutes
# oc debug node/qe-yapei45-xxxx-master-0.c.openshift-qe.internal
Starting pod/qe-yapei45-xxxx-master-0copenshift-qeinternal-debug ...
To use host binaries, run `chroot /host`
Pod IP: 10.0.0.4
If you don't see a command prompt, try pressing enter.
sh-4.2# chroot /host
sh-4.4# cd /root
sh-4.4# ls
test.sh
sh-4.4# bash test.sh &
[1] 1564316

2. After connection recovered, reconnected to node, check if the such error messages in bug can be found, 
kubelet logs, 
$ oc debug node/ip-xx-0-xxx-242.us-east-2.compute.internal
sh-4.4# journalctl -b -u kubelet |  grep -i 'Too large resource version'

No longer see the such error messages in kubelet logs.


3. I think for each component, we should check component operator logs, then I checked console-operator logs, also didn't see 'Too large resource version' errors
# oc logs console-operator-5ffd57b9b-8t294 -n openshift-console-operator | grep -i 'too large'   // nothing returns

Moving to VERIFIED on 4.5.0-0.nightly-2020-10-10-013307


Do let me know if my steps are wrong. Thanks

Comment 7 errata-xmlrpc 2020-10-19 14:54:26 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (OpenShift Container Platform 4.5.15 bug fix update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2020:4228