Bug 1989246 - openshift-network-operator needs to handle API server downtime gracefully in SNO
Summary: openshift-network-operator needs to handle API server downtime gracefully in SNO
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: OpenShift Container Platform
Classification: Red Hat
Component: Networking
Version: 4.9
Hardware: Unspecified
OS: Linux
high
high
Target Milestone: ---
: 4.9.0
Assignee: Christoph Stäbler
QA Contact: zhaozhanqi
URL:
Whiteboard: chaos
Depends On:
Blocks: 1984730
TreeView+ depends on / blocked
 
Reported: 2021-08-02 17:42 UTC by Naga Ravi Chaitanya Elluri
Modified: 2021-10-18 17:44 UTC (History)
3 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2021-10-18 17:43:52 UTC
Target Upstream Version:
Embargoed:
cstabler: needinfo-


Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Github openshift cluster-network-operator pull 1175 0 None None None 2021-08-04 10:28:49 UTC
Red Hat Product Errata RHSA-2021:3759 0 None None None 2021-10-18 17:44:03 UTC

Description Naga Ravi Chaitanya Elluri 2021-08-02 17:42:00 UTC
Description of problem:
This bug is not related to core openshift sdn or ovn-kubernetes, it is with respect to the network operator.


openshift-network-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 ).openshift-network-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 network-operator leader lease failures in the log: http://dell-r510-01.perf.lab.eng.rdu2.redhat.com/chaos/sno/openshift-network-operator/leader_election.log that ties to the restart:http://dell-r510-01.perf.lab.eng.rdu2.redhat.com/chaos/sno/openshift-network-operator/cerberus_cluster_state.log. The leader election can also be disabled given that there's no HA.


Version-Release number of selected component (if applicable):
4.9.0-0.nightly-2021-08-01-132055

How reproducible:
Always

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

Actual results:
network-operator is crashing/restarting and going through leader elections.

Expected results:
network-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/openshift-network-operator/.

Comment 5 zhaozhanqi 2021-08-18 06:49:27 UTC
Verified this bug on 4.9.0-0.nightly-2021-08-17-183417

After patch kubeapiserver with 
oc patch kubeapiserver/cluster --type merge -p '{"spec":{"forceRedeploymentReason":"something2"}}'

CNO pod did not restarted.

Comment 8 errata-xmlrpc 2021-10-18 17:43:52 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


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