Bits of .NET

📈 HPA = Automatic Scaling

Traffic changes constantly. Horizontal Pod Autoscaler scales automatically. More pods when needed, less when not.

📝 HPA Setup

# Install metrics-server
kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml

# Verify metrics-server
kubectl top pods
kubectl top nodes

# Create HPA
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
    name: web-hpa
spec:
    scaleTargetRef:
        apiVersion: apps/v1
        kind: Deployment
        name: web
    minReplicas: 2
    maxReplicas: 10
    metrics:
    - type: Resource
        resource:
            name: cpu
            target:
                type: Utilization
                averageUtilization: 70
    - type: Resource
        resource:
            name: memory
            target:
                type: Utilization
                averageUtilization: 80

# Create HPA via command
kubectl autoscale deployment web --cpu-percent=70 --min=2 --max=10

# Check HPA status
kubectl get hpa
kubectl describe hpa web-hpa

🎯 Advanced HPA

# Custom metrics (Prometheus)
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
    name: custom-hpa
spec:
    scaleTargetRef:
        apiVersion: apps/v1
        kind: Deployment
        name: app
    minReplicas: 2
    maxReplicas: 20
    metrics:
    - type: Pods
        pods:
            metric:
                name: http_requests_per_second
            target:
                type: AverageValue
                averageValue: 100

# Multiple metrics
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
    name: multi-metric-hpa
spec:
    metrics:
    - type: Resource
        resource:
            name: cpu
            target:
                type: Utilization
                averageUtilization: 60
    - type: Resource
        resource:
            name: memory
            target:
                type: Utilization
                averageUtilization: 75
    - type: Pods
        pods:
            metric:
                name: requests_per_second
            target:
                type: AverageValue
                averageValue: 500

# Behavior configuration
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
    name: behavior-hpa
spec:
    behavior:
        scaleDown:
            stabilizationWindowSeconds: 300
            policies:
            - type: Percent
                value: 10
                periodSeconds: 60
        scaleUp:
            stabilizationWindowSeconds: 0
            policies:
            - type: Percent
                value: 100
                periodSeconds: 30
            - type: Pods
                value: 4
                periodSeconds: 30
            selectPolicy: Max

💡 HPA Tips

• Set appropriate min/max replicas
• Monitor HPA behavior
• Use custom metrics for business logic
• Consider VPA for vertical scaling
• Test scaling scenarios