How to implement Blue-Green deployment in Kubernetes with Argo Rollouts?

Question

Accepted Answer

**Blue-Green with Argo Rollouts** — two environments, instant switching.

```yaml
apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  name: myapp
spec:
  replicas: 5
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
        - name: myapp
          image: myapp:2.0
          ports:
            - containerPort: 8080
  strategy:
    blueGreen:
      activeService: myapp-active
      previewService: myapp-preview
      autoPromotionEnabled: false
      prePromotionAnalysis:
        templates:
          - templateName: success-rate
        args:
          - name: service-name
            value: myapp-preview
      postPromotionAnalysis:
        templates:
          - templateName: success-rate
        args:
          - name: service-name
            value: myapp-active
      scaleDownDelaySeconds: 300
      prePromotionAnalysisTemplates:
        - templateName: smoke-test
```

**Active/Preview Services:**
```yaml
apiVersion: v1
kind: Service
metadata:
  name: myapp-active
spec:
  selector:
    app: myapp
  ports:
    - port: 80
      targetPort: 8080
---
apiVersion: v1
kind: Service
metadata:
  name: myapp-preview
spec:
  selector:
    app: myapp
  ports:
    - port: 80
      targetPort: 8080
```

**Promotion:**
```bash
kubectl argo rollouts promote myapp
kubectl argo rollouts reject myapp  # rollback
kubectl argo rollouts status myapp
kubectl argo rollouts get rollout myapp --watch
```

**PrePromotionAnalysis** — verification of preview before switching. **PostPromotionAnalysis** — verification of active after switching.

DevOps: How to implement Blue-Green deployment in Kubernetes with Argo Rollouts?