Multi-Cluster Management Pattern

Multi-cluster setups need a control plane. The patterns: ArgoCD, Flux, Anthos, Rancher.

The control plane choice

ArgoCD is the GitOps standard for multi-cluster. One ArgoCD instance manages many clusters; per-cluster Applications drive deploys. Strong UI, clear audit trail.

Flux is the lighter-weight GitOps option. CRD-driven; less UI; works well for teams that prefer YAML-only.

Rancher and Anthos are full-platform options. Cluster lifecycle plus apps plus policy. Heavier; opinionated; best for hybrid cloud or on-prem.

Cluster API for cluster lifecycle

Cluster API (CAPI) standardises cluster provisioning. Per-cloud providers handle the underlying infrastructure; CAPI gives a consistent interface.

Useful when you create and tear down clusters frequently: ephemeral test environments, per-customer clusters, blue-green cluster upgrades.

Operational complexity is real. CAPI has its own CRDs, controllers, lifecycle. Smaller orgs are better off with cloud-native tooling (eksctl, gcloud).

Policy across clusters

OPA Gatekeeper or Kyverno enforces consistent policy across clusters. Image admission, label requirements, resource limits.

Centralised policy repo, distributed enforcement. Policies live in git; agents enforce per-cluster.

Audit reports per cluster. Drift between policy intent and reality surfaces. Quarterly: any clusters out of compliance?

Observability across clusters

Per-cluster Prometheus federated to a central one (Thanos, Cortex, or Grafana Cloud). Per-cluster local queries; cross-cluster aggregates.

Logs to a shared backend (Loki, Elasticsearch). Cluster identity as a label; queries by cluster.

Multi-cluster dashboards: aggregate health view. Per-cluster drill-down. Standard pattern for fleet-of-clusters operations.

Operating the fleet

Per-cluster owners. Even with centralised platform, each cluster has someone responsible. Empty ownership is operational debt.

Standard cluster template. New clusters look like existing ones. Custom clusters are exceptions, documented.

Quarterly fleet review. Cluster inventory, version skew, addon versions. Drift is normal; unmanaged drift is the issue.