Bug 1986477

Summary:	cluster-node-tuning-operator needs to handle API server downtime gracefully in SNO
Product:	OpenShift Container Platform	Reporter:	Naga Ravi Chaitanya Elluri <nelluri>
Component:	Node Tuning Operator	Assignee:	Jiří Mencák <jmencak>
Status:	CLOSED ERRATA	QA Contact:	liqcui
Severity:	high	Docs Contact:
Priority:	high
Version:	4.9	CC:	aos-bugs, dagray, liqcui, nelluri
Target Milestone:	---
Target Release:	4.9.0
Hardware:	Unspecified
OS:	Linux
Whiteboard:	chaos
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-10-18 17:42:20 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:
Bug Blocks:	1984730, 1986992

Description Naga Ravi Chaitanya Elluri 2021-07-27 16:27:44 UTC

Description of problem:
Cluster-node-tuning-operator is crashing/restarting and is going though leader elections during the kube-apiserver rollout which takes around ~60 seconds with shutdown-delay-duration and gracefulTerminationDuration is now set to 0 and 15 seconds ( https://github.com/openshift/cluster-kube-apiserver-operator/pull/1168 and https://github.com/openshift/library-go/pull/1104 ). cluster-node-tuning-operator leader election timeout should be set to > 60 seconds to handle the downtime gracefully in SNO.

Recommended lease duration values to be considered for reference as noted in https://github.com/openshift/enhancements/pull/832/files#diff-2e28754e69aa417e5b6d89e99e42f05bfb6330800fa823753383db1d170fbc2fR183:

LeaseDuration=137s, RenewDealine=107s, RetryPeriod=26s.
These are the configurable values in k8s.io/client-go based leases and controller-runtime exposes them.
This gives us
1. clock skew tolerance == 30s
2. kube-apiserver downtime tolerance == 78s
3. worst non-graceful lease reacquisition == 163s
4. worst graceful lease reacquisition == 26s

We can see that leader lease failures in the log: http://dell-r510-01.perf.lab.eng.rdu2.redhat.com/chaos/sno/cluster-node-tuning-operator/cluster-node-tuning-operator.log. The leader election can also be disabled given that there's no HA in SNO.

Version-Release number of selected component (if applicable):
4.9.0-0.nightly-2021-07-26-031621

How reproducible:
Always

Steps to Reproduce:
1. Install a SNO cluster using the latest nightly payload.
2. Trigger kube-apiserver rollout/outage that lasts at least 60 seconds - $oc patch kubeapiserver/cluster --type merge -p '{"spec":{"forceRedeploymentReason":"ITERATIONX"}}' where X can be 1,2...n
3. Observe the state of cluster-node-tuning-operator.

Actual results:
cluster-node-tuning-operator is crashing/restarting and going through leader elections.

Expected results:
cluster-node-tuning-operator should handle the API rollout/outage gracefully.

Additional info:
Logs including must-gather: http://dell-r510-01.perf.lab.eng.rdu2.redhat.com/chaos/sno/cluster-node-tuning-operator/

Comment 2 liqcui 2021-08-03 10:37:02 UTC

Verified Steps:

Cluster Version:
4.9.0-0.nightly-2021-08-02-145924

Test Steps:
Startup SNO Cluster and delete api-server one by one and delete all api-server one time

time oc delete pod apiserver-8568699655-kdlwj -n openshift-apiserver;time oc delete pod apiserver-8568699655-p2dhz -n openshift-apiserver;time oc delete pod apiserver-8568699655-vsl6z -n openshift-apiserver
pod "apiserver-8568699655-kdlwj" deleted

real    1m17.189s
user    0m0.155s
sys     0m0.063s
pod "apiserver-8568699655-p2dhz" deleted

real    1m21.086s
user    0m0.107s
sys     0m0.038s
pod "apiserver-8568699655-vsl6z" deleted

real    1m17.096s
user    0m0.120s
sys     0m0.024s
Test Result:
No POD restarted during api-server rollout
oc get pods -n openshift-cluster-node-tuning-operator
NAME                                           READY   STATUS    RESTARTS   AGE
cluster-node-tuning-operator-b8d46fb9d-v8gzl   1/1     Running   0          62m
tuned-9pwkq                                    1/1     Running   0          60m
tuned-fmkjw                                    1/1     Running   0          60m
tuned-gmpmn                                    1/1     Running   0          60m

Comment 5 errata-xmlrpc 2021-10-18 17:42:20 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 (Moderate: OpenShift Container Platform 4.9.0 bug fix and security 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/RHSA-2021:3759