Multi-Cluster GitOps Management (2024-2025)

ArgoCD ApplicationSets

Cluster Generator (auto-discover clusters):

apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: my-apps
spec:
  generators:
  - cluster:
      selector:
        matchLabels:
          environment: production
  template:
    spec:
      source:
        repoURL: https://github.com/org/repo
        path: apps/{{name}}
      destination:
        server: '{{server}}'

Matrix Generator (Cluster x Apps):

generators:
- matrix:
    generators:
    - cluster: {}
    - git:
        directories:
        - path: apps/*

Performance: 83% faster than manual (30min → 5min)

Flux Multi-Cluster

Option 1: Flux Per Cluster

cluster-1/ → Flux instance 1
cluster-2/ → Flux instance 2

Option 2: Hub-and-Spoke

management-cluster/
└── flux manages → cluster-1, cluster-2

Setup:

flux bootstrap github --owner=org --repository=fleet \
  --path=clusters/production --context=prod-cluster

Hub-and-Spoke Pattern

Benefits: Centralized management, single source of truth Cons: Single point of failure Best for: < 50 clusters

Workload Identity (2025 Best Practice)

Instead of service account tokens, use:

AWS IRSA
GCP Workload Identity
Azure AD Workload Identity

No more long-lived credentials!

Best Practices

Cluster labeling for organization
Progressive rollout (dev → staging → prod clusters)
Separate repos for cluster config vs apps
Monitor sync status across all clusters
Use workload identity (no static credentials)

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