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Multi-Cluster Management with ArgoCD

/ 2 min read

kubernetes , argocd , gitops , devops , cloud-native , multi-cluster , series:argocd:3

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Multi-Cluster Management with ArgoCD

In this third part of our ArgoCD series, we’ll explore how to effectively manage multiple Kubernetes clusters using ArgoCD.

Cluster Registration

Adding Clusters

Terminal window
# Get cluster credentials
kubectl config get-context


# Add cluster to ArgoCD
argocd cluster add my-cluster-context

Via YAML

apiVersion: v1
kind: Secret
metadata:
  name: mycluster-secret
  namespace: argocd
  labels:
    argocd.argoproj.io/secret-type: cluster
type: Opaque
stringData:
  name: mycluster
  server: https://kubernetes.default.svc
  config: |
    {
      "bearerToken": "<token>",
      "tlsClientConfig": {
        "insecure": false,
        "caData": "<ca-data>"
      }
    }

Multi-Cluster Strategies

Hub and Spoke Model

  • Central ArgoCD instance (Hub)
  • Multiple target clusters (Spokes)
  • Unified management interface

Federation Model

  • Multiple ArgoCD instances
  • Cluster-specific configurations
  • Delegated administration

Secrets Management

Using External Secrets

apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: my-secret
spec:
  refreshInterval: 1h
  secretStoreRef:
    name: vault-backend
    kind: ClusterSecretStore
  target:
    name: my-secret
  data:
    - secretKey: password
      remoteRef:
        key: secret/data/myapp
        property: password

Sealed Secrets

apiVersion: bitnami.com/v1alpha1
kind: SealedSecret
metadata:
  name: mysecret
spec:
  encryptedData:
    password: AgBy8hCi...

Advanced Deployment Strategies

Progressive Delivery

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: myapp
spec:
  source:
    plugin:
      name: progressive-delivery
    repoURL: https://github.com/org/myapp.git
  destination:
    server: https://kubernetes.default.svc

Cluster Groups

apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: myapp-set
spec:
  generators:
  - clusters:
      selector:
        matchLabels:
          environment: production
  template:
    spec:
      source:
        repoURL: https://github.com/org/myapp.git
      destination:
        server: '{{server}}'

Configuration Management

Using Kustomize

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: myapp
spec:
  source:
    path: overlays/production
    kustomize:
      images:
      - myapp=myregistry/myapp:1.0.0

Using Helm

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: myapp
spec:
  source:
    chart: myapp
    helm:
      values: |
        image:
          tag: 1.0.0
        replicas: 3

Monitoring and Observability

Prometheus Integration

apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: argocd-metrics
spec:
  selector:
    matchLabels:
      app.kubernetes.io/name: argocd-metrics
  endpoints:
  - port: metrics

Grafana Dashboards

  • Application sync status
  • Resource health
  • Cluster metrics
  • Error rates

Best Practices

  1. Cluster Organization

    • Label clusters by environment/purpose
    • Use consistent naming conventions
    • Document cluster access patterns

  2. Security

    • Implement cluster RBAC
    • Use network policies
    • Rotate cluster credentials

  3. Resource Management

    • Set cluster resource quotas
    • Monitor cluster capacity
    • Implement cost allocation

Troubleshooting

Common Issues

  1. Cluster connectivity
  2. Authentication failures
  3. Resource conflicts
  4. Network policies

Debug Commands

Terminal window
# Check cluster status
argocd cluster list


# Verify connectivity
argocd admin cluster-info


# Check logs
kubectl logs -n argocd -l app.kubernetes.io/name=argocd-server

Conclusion

Multi-cluster management with ArgoCD requires:

  • Proper cluster registration and authentication
  • Effective secrets management
  • Advanced deployment strategies
  • Robust monitoring and observability

In the next part, we’ll cover:

  • Custom resource definitions
  • Webhook integrations
  • Advanced automation patterns
  • Disaster recovery strategies