Open Cluster Management: A Hub for Your Kubernetes Fleet
Shriira Press
How a hub cluster and a fleet of pull-based agents turn many Kubernetes clusters into one manageable whole.
Welcome to Open Cluster Management: A Hub for Your Kubernetes Fleet.
Once an organization runs more than a handful of Kubernetes clusters — across regions, clouds, and edge sites — the comfortable single-cluster mental model breaks down. Open Cluster Management (OCM) is a CNCF project that answers the question of how to govern many clusters from one place without turning the control plane into a brittle bottleneck. It introduces a hub cluster that holds an inventory of managed clusters, and a lightweight agent called the klusterlet that runs on each managed cluster and pulls its instructions rather than waiting to be pushed to. This book walks through the whole system: the hub-and-spoke architecture and why pull beats push at scale; the double opt-in registration handshake that safely admits a cluster; the ManagedCluster inventory and how clusters are grouped into sets; Placement and PlacementDecision for choosing which clusters should do what; ManifestWork for shipping and tracking workloads; the addon framework that extends agents cleanly; and the governance policy framework that keeps a fleet compliant. We finish with operating OCM in practice and where it sits in the cloud-native ecosystem.
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