What’s New in Kubernetes 1.21? Explore 51 Enhancements and Core Features
Kubernetes 1.21, the first 2021 release, introduces 51 enhancements—including stable CronJobs, immutable Secrets/ConfigMaps, dual‑stack IPv4/IPv6 support, graceful node shutdown, and new health monitoring for PersistentVolumes—while deprecating PodSecurityPolicy and TopologyKeys and offering a suite of new beta and stable features for cloud‑native workloads.
We are pleased to announce Kubernetes 1.21, the first release of 2021, which brings 51 enhancements: 13 reach stable, 16 become beta, 20 enter alpha, and 2 are deprecated.
Core Topics
CronJobs Reach Stable
Since Kubernetes 1.8, CronJobs (formerly ScheduledJobs) have been beta; in 1.21 they finally graduate to stable, enabling reliable periodic tasks such as backups and report generation.
Immutable Secrets and ConfigMaps
Immutable Secrets and ConfigMaps add a new field that prevents changes to these objects, reducing errors caused by accidental modifications. To update them, create a new Secret or ConfigMap with a unique name and redeploy the pods that use it. This feature is now stable in 1.21.
IPv4/IPv6 Dual‑Stack Support
IPv4 addresses are scarce, so Kubernetes 1.21 enables dual‑stack networking, allowing pods and services to receive both IPv4 and IPv6 addresses by default (beta). This improves scalability and mitigates IP‑address exhaustion.
Node Graceful Shutdown
Node graceful shutdown is now in beta. Kubelet detects system shutdown via systemd, notifies running pods, and allows them to terminate cleanly, preventing abrupt pod termination.
PersistentVolume Health Monitoring
A new alpha feature monitors the health of PersistentVolumes, marking unhealthy volumes so workloads can avoid reading from or writing to them.
Reduced Build Maintenance Workload
The Kubernetes build system has been simplified and standardized on native Go tooling, lowering the entry barrier for new contributors and improving overall maintainability.
Main Changes
Deprecate PodSecurityPolicy
PodSecurityPolicy is deprecated in 1.21; its beta version will remain until removal in 1.25. A new built‑in mechanism called “PSP replacement policy” will eventually cover its use cases.
Deprecate TopologyKeys
Service field topologyKeys is deprecated; it was alpha and is replaced by the new topology‑aware hints feature, introduced as an alpha in 1.21.
Other Updates
Features Reaching Stable
EndpointSlice
New sysctl support
PodDisruptionBudgets
Important Feature Updates
External client‑go credential providers – beta in 1.21
Structured logging – beta in 1.22
TTL after finish cleanup for Jobs and Pods – beta in 1.21
Release Notes
For full details, see the official release notes.
Release Information
Kubernetes 1.21 is available on GitHub. You can explore interactive tutorials on the Kubernetes site, run a local cluster with kind, or follow the “Kubernetes the Hard Way” guide to build a cluster from scratch.
Related Links
PodSecurityPolicy deprecation article
Topology‑aware hints KEP
Kubernetes 1.21 changelog
Release v1.21.0
Kubernetes tutorials
Kubernetes the Hard Way
Original source: https://kubernetes.io/blog/2021/04/08/kubernetes-1-21-release-announcement/ – reproduced by Distributed Lab (© original author).
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