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 machine-config-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.
any update? what's the current status?
I'll look into this in the next sprint.
Hi, do we have any update on that? Is someone working on it?
You need to update client-go library, the minimum version is 1.18.6.
Let me know once you have a PR. I can review it. Thanks.
Verified on registry.ci.openshift.org/ocp/release:4.5.0-0.nightly-2021-02-04-091104 by checking that the commit contains the k8s.io/client-go to 0.18.6 bump
Media Type: application/vnd.docker.distribution.manifest.v2+json
Created: 1d ago
Image Size: 144.5MB in 5 layers
Layers: 76.42MB sha256:eae19a56e9c600eb0a59816d9d0ad7065824a34a13be60469084304fc7170334
description=This is the base image from which all OpenShift Container Platform images inherit.
io.k8s.description=This is the base image from which all OpenShift Container Platform images inherit.
io.k8s.display-name=OpenShift Container Platform RHEL 7 Base
io.openshift.maintainer.component=Machine Config Operator
io.openshift.maintainer.product=OpenShift Container Platform
summary=Provides the latest release of the Red Hat Universal Base Image 7.
vendor=Red Hat, Inc.
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 (Important: OpenShift Container Platform 4.5.31 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.