What’s new in Kubernetes v1.21.2?

Published 23.06.2021

Categories Changelog

It’s June, and Kubernetes has released a new update with version 1.21.2. We will have a look in brief at the changes that came along with this update. We will also have a look at the bugs that Kubernetes removed ahead with the few things added. Let’s roll.

Changes Since v1.21.1

Let’s look at the several changes that have taken place.


Golang 1.16.5 helped in building Kubernetes v1.21.2 [SIG Cloud Provider, Instrumentation, Release and Testing]

Setcap Image updates to buster-v2.0.1 [SIG Release]


The new update fixes the “Should Receive Events” on concurrent watches in the same order conformance test to work correctly on clusters that auto-create additional configmaps in namespaces. [SIG API Machinery and Testing]

Bugs and Regression

In the new update, the jitter factor is added to the lease controller to better smear load on Kube-Apiserver over time. [SIG API Machinery and Testing]

For those whose network profile is nil, avoid caching the Azure VMSS instances [SIG Cloud Provider]

When updating VMSS and VMSS instances in Microsoft Azure, we have to avoid setting cached Sku [SIG Cloud Provider]

A bug is fixed on the endpoint slices mirroring controller where mirroring of endpoint NotReadyAddresses as Ready to the corresponding EndpointSlice [SIG Apps and Network]

A bug that got fixed shows that a preemptor pod may exist as a phantom in the scheduler. [SIG Scheduling]

Fix removing pods from podTopologyHints mapping [SIG Node]

New update fixed the resource enforcement when using systemd cgroup driver [SIG API Machinery, Cloud Provider, CLI, Cluster Lifecycle, Instrumentation, Node, Storage and Testing]

Another fix shows to avoid nil-pointer panic when checking the frontend IP configuration [SIG Cloud Provider]

A new fix is done not to tag static public IP [SIG Cloud Provider]

Fixing the false-positive uncertain volume attachments, which led to unexpected detachment of CSI migrated volumes [SIG Apps and Storage]

Fixation of garbage collection of dangling VolumeAttachments for PersistentVolumes migrated to CSI on startup of Kube-controller-manager. [SIG Apps and Storage]

Kube-proxy log now shows the “Skipping topology-aware endpoint filtering since they don’t give any hints for zone” warning under the right conditions [SIG Network]

Kubeadm: In the new update, we now see removing the “ephemeral_storage” request received from the etcd static pod that kubeadm readily deploys on stacked etcd control plane nodes. The demand has caused sporadic failures on some setups due to problems in kubelet with cadvisor and LocalStorageCapacityIsolation feature gate. For more details, we can see https://github.com/kubernetes/kubernetes/issues/99305  [SIG Cluster Lifecycle]

Kubeadm: When we will use a custom image repository for CoreDNS, kubeadm will now append the “coredns” image name instead of “coredns/coredns”, thus the new update restoring the existing behaviour v1.21 release. Users who rely on a nested folder for the coredns image should set the “clusterConfiguration.dns.imageRepository” value including the nested pathname (e.g. using “registry.company.xyz/coredns” will now force kubeadm to use “registry.company.xyz/coredns/coredns” image). Furthermore, no action is needed if someone uses the default registry (k8s.gcr.io). [SIG Cluster Lifecycle]

Registering and deregistering of targets in chunks for AWS TargetGroup [SIG Cloud Provider]

In the new update, the server-side apply updates to the client-side to apply annotation for respecting the annotation size limit. Also, another fix to show the opt-out of this behaviour by setting the client-side apply annotation to the empty string. [SIG API Machinery]

Reverted the previous fix for portforward clean up because it has introduced a kubelet regression, leading to segmentation faults. [SIG API Machinery and Node]


Client-go: reduce the verbosity of “Starting/Stopping reflector” messages to 3 again [SIG API Machinery]

Updating the Debian images to pick up CVE fixes in the base images:

  • Updating the Debian-base image to v1.7.0
  • Updating the Debian-iptables image to v1.6.1 [SIG API Machinery and Testing]

Added Dependencies for Kubernetes v1.21.2

Changed Dependencies for Kubernetes 1.21.2

Removed Dependencies

github.com/checkpoint-restore/go-criu/v4: v4.1.0

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