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Cluster API v1.12: Introducing In-place Updates and Chained Upgrades
Cluster API provides declarative management for Kubernetes cluster lifecycles. It utilizes controllers to reconcile cluster states, similar to how Kubernetes manages Pods with Deployments. The v1.12.0 release introduces significant enhancements, namely in-place updates and chained upgrades, to streamline common operations. In-place updates allow modifications to machines without full recreation, adopting an immutable infrastructure principle for simplicity and predictability. This new feature enables Cluster API to intelligently choose between immutable rollouts and in-place updates based on the nature of the change. Cluster API considers in-place updates most beneficial for changes not requiring node drains, like credential updates. Chained upgrades, on the other hand, allow users to jump multiple Kubernetes minor versions in a single operation. This feature computes and executes an upgrade plan, orchestrating control plane and worker machine updates sequentially. Worker machines intelligently skip intermediate versions when Kubernetes version skew policies permit. Extensibility through update extensions and upgrade plan runtime extensions ensures flexibility. Cluster API continues to evolve, focusing on safer upgrades and reduced disruption for managing Kubernetes at scale.