How to use ArgoCD for multi-cluster management?

Question

Accepted Answer

**ArgoCD multi-cluster** — one ArgoCD server manages multiple Kubernetes clusters.

**Cluster registration:**
```bash
argocd cluster add production-context
argocd cluster add staging-context
argocd cluster list
```

**Application to another cluster:**
```yaml
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: myapp-production
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://github.com/org/k8s-manifests
    targetRevision: main
    path: overlays/production
  destination:
    server: https://production-cluster.example.com
    namespace: production
  syncPolicy:
    automated:
      prune: true
      selfHeal: true
```

**ApplicationSet (all clusters):**
```yaml
apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: myapp-all-clusters
spec:
  generators:
    - clusters:
        selector:
          matchLabels:
            environment: production
  template:
    metadata:
      name: "myapp-{{name}}"
    spec:
      source:
        repoURL: https://github.com/org/k8s-manifests
        path: overlays/production
      destination:
        server: "{{server}}"
        namespace: production
      syncPolicy:
        automated:
          prune: true
          selfHeal: true
```

**Hub-and-Spoke:** One central ArgoCD → multiple clusters.

**ApplicationSet with Matrix (cluster × environment):**
```yaml
generators:
  - matrix:
      generators:
        - clusters:
            selector:
              matchLabels:
                env: production
        - git:
            repoURL: https://github.com/org/apps
            revision: main
            directories:
              - path: apps/*
```

**AppProject (restrictions):**
```yaml
apiVersion: argoproj.io/v1alpha1
kind: AppProject
metadata:
  name: team-orders
  namespace: argocd
spec:
  sourceRepos:
    - "https://github.com/org/k8s-manifests"
  destinations:
    - server: https://production-cluster.example.com
      namespace: "orders-*"
    - server: https://staging-cluster.example.com
      namespace: "orders-*"
  clusterResourceWhitelist: []
  namespaceResourceWhitelist: []
```

**Security:** RBAC for clusters, projects restrict deployments.

DevOps: How to use ArgoCD for multi-cluster management?