GitOps Multi-Cluster Management

# สร้าง namespace สำหรับ ArgoCD
kubectl create namespace argocd

# ติดตั้ง ArgoCD ด้วย manifest จาก official
kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

# ตรวจสอบสถานะ pods
kubectl get pods -n argocd

# รอจนกว่า pods ทั้งหมดจะพร้อม (ประมาณ 2-3 นาที)
kubectl wait --for=condition=available --timeout=600s deployment/argocd-server -n argocd

# ตั้งค่า LoadBalancer หรือใช้ port-forward (สำหรับ testing)
kubectl port-forward svc/argocd-server -n argocd 8080:443

# ดึงรหัสผ่านเริ่มต้น (username: admin)
kubectl -n argocd get secret argocd-initial-admin-secret -o jsonpath="{.data.password}" | base64 -d

# เข้าถึง UI ได้ที่ https://localhost:8080

# สำหรับ Linux
curl -sSL -o argocd-linux-amd64 https://github.com/argoproj/argo-cd/releases/latest/download/argocd-linux-amd64
sudo install -m 555 argocd-linux-amd64 /usr/local/bin/argocd
rm argocd-linux-amd64

# สำหรับ macOS
brew install argocd

# Login เข้า ArgoCD
argocd login localhost:8080 --grpc-web

# ตั้งค่า context ของ cluster ที่ต้องการเพิ่ม
kubectl config use-context dev-cluster

# เพิ่ม cluster เข้าสู่ ArgoCD
argocd cluster add dev-cluster --name dev-cluster

# เพิ่ม Staging cluster
kubectl config use-context staging-cluster
argocd cluster add staging-cluster --name staging-cluster

# เพิ่ม Production cluster
kubectl config use-context prod-cluster-1
argocd cluster add prod-cluster-1 --name prod-cluster-1

# ตรวจสอบ clusters ทั้งหมด
argocd cluster list

apiVersion: v1
kind: Secret
metadata:
  name: prod-cluster-1-secret
  namespace: argocd
  labels:
    argocd.argoproj.io/secret-type: cluster
type: Opaque
stringData:
  name: prod-cluster-1
  server: https://prod-cluster-1.example.com:6443
  config: |
    {
      "bearerToken": "eyJhbGciOiJSUzI1NiIsImtpZCI6...",
      "tlsClientConfig": {
        "insecure": false,
        "caData": "LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0t..."
      }
    }

apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: webapp-multi-cluster
  namespace: argocd
spec:
  # ใช้ List Generator กำหนด clusters ที่ต้องการ deploy
  generators:
  - list:
      elements:
      - cluster: dev-cluster
        url: https://dev-cluster.example.com:6443
        env: dev
        replicas: "1"
      - cluster: staging-cluster
        url: https://staging-cluster.example.com:6443
        env: staging
        replicas: "2"
      - cluster: prod-cluster-1
        url: https://prod-cluster-1.example.com:6443
        env: prod
        replicas: "3"
      - cluster: prod-cluster-2
        url: https://prod-cluster-2.example.com:6443
        env: prod
        replicas: "3"
  
  # Template สำหรับสร้าง Application
  template:
    metadata:
      name: 'webapp-{{env}}-{{cluster}}'
      labels:
        app: webapp
        environment: '{{env}}'
    spec:
      project: default
      source:
        repoURL: https://github.com/your-org/webapp-manifests.git
        targetRevision: main
        path: 'overlays/{{env}}'
        helm:
          parameters:
          - name: replicaCount
            value: '{{replicas}}'
      destination:
        server: '{{url}}'
        namespace: webapp
      syncPolicy:
        automated:
          prune: true
          selfHeal: true
        syncOptions:
        - CreateNamespace=true

apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: webapp-all-clusters
  namespace: argocd
spec:
  generators:
  - clusters:
      selector:
        matchLabels:
          argocd.argoproj.io/secret-type: cluster
          environment: production  # เลือกเฉพาะ production clusters
  template:
    metadata:
      name: 'webapp-{{name}}'
    spec:
      project: default
      source:
        repoURL: https://github.com/your-org/webapp-manifests.git
        targetRevision: main
        path: overlays/production
      destination:
        server: '{{server}}'
        namespace: webapp
      syncPolicy:
        automated:
          prune: true
          selfHeal: true

webapp-manifests/
├── base/                      # Base manifests (kustomize)
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── configmap.yaml
│   └── kustomization.yaml
├── overlays/
│   ├── dev/                   # Dev environment overrides
│   │   ├── kustomization.yaml
│   │   └── patches/
│   │       └── replica-patch.yaml
│   ├── staging/               # Staging environment overrides
│   │   ├── kustomization.yaml
│   │   └── patches/
│   └── production/            # Production environment overrides
│       ├── kustomization.yaml
│       └── patches/
├── applicationset.yaml        # ApplicationSet definition
└── README.md

#!/bin/bash

# กำหนดรายการ clusters
CLUSTERS=(
    "dev-cluster:dev-cluster-context"
    "staging-cluster:staging-cluster-context"
    "prod-cluster-1:prod-cluster-1-context"
    "prod-cluster-2:prod-cluster-2-context"
)

# Loop ผ่าน clusters และลงทะเบียน
for cluster_info in "${CLUSTERS[@]}"; do
    IFS=':' read -r name context <<< "$cluster_info"
    
    echo "Registering cluster: $name"
    
    # Switch context
    kubectl config use-context "$context"
    
    # Register cluster
    argocd cluster add "$context" --name "$name" --grpc-web
    
    # เพิ่ม labels สำหรับใช้กับ ApplicationSet
    kubectl label secret -n argocd "${name}-cluster-secret" \
        environment="${name%%-*}" \
        argocd.argoproj.io/secret-type=cluster
    
    echo "✓ Cluster $name registered successfully"
done

echo "All clusters registered!"
argocd cluster list