What’s New in Kubernetes 1.21? A Deep Dive into Core Features and Changes
Kubernetes 1.21 introduces 51 enhancements—including stable CronJobs, immutable Secrets/ConfigMaps, dual‑stack networking, graceful node shutdown, and PersistentVolume health monitoring—while deprecating PodSecurityPolicy and topologyKeys, and provides links to full release notes and download resources.
We are pleased to announce the release of Kubernetes v1.21, the first version released in 2021, which introduces 51 enhancements: 13 promoted to stable, 16 to beta, 20 to alpha, and 2 deprecated.
The release process itself changed: instead of a community‑driven synchronous communication model, feature inclusion now depends on community decisions, increasing collaboration across teams.
Key Highlights
CronJobs reach stable
CronJobs, originally introduced as a beta feature in v1.8, become a stable API in v1.21, enabling reliable periodic tasks such as backups and report generation.
Immutable Secrets and ConfigMaps
New immutable fields prevent accidental changes to Secrets and ConfigMaps. To modify them, users must create a new resource with a unique name and redeploy pods, reducing the need for controllers to poll the API server.
IPv4/IPv6 Dual‑Stack Support
Dual‑stack networking enters beta and is enabled by default, allowing pods and services to obtain both IPv4 and IPv6 addresses, alleviating IPv4 scarcity and improving scalability.
Graceful Node Shutdown
This beta feature lets kubelet detect system shutdown via systemd and notify running pods, enabling them to terminate cleanly instead of abrupt termination.
PersistentVolume Health Monitoring
An alpha feature adds a health monitor for PersistentVolumes, marking unhealthy volumes so workloads can avoid reading from or writing to them.
Deprecations
PodSecurityPolicy – deprecated now, will be removed in v1.25; a replacement “PSP replacement policy” is planned.
TopologyKeys – the Service field topologyKeys is deprecated; topology‑aware hints (beta) will replace it.
Other Stable Features
EndpointSlice
Sysctl support
PodDisruptionBudgets
Important Feature Updates
External client‑go credential providers – beta in v1.21
Structured logging – beta in v1.22
TTL after finish cleanup for Jobs and Pods – beta in v1.21
Release Information
Full release notes are available in the Kubernetes changelog. The binaries can be downloaded from the official GitHub release page, and tutorials such as “Kubernetes the Hard Way” are linked for hands‑on learning.
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