Kubernetes自动伸缩

自动伸缩类型

类型	说明
HPA	水平Pod自动伸缩
VPA	垂直Pod自动伸缩
Cluster Autoscaler	集群节点自动伸缩

水平Pod自动伸缩（HPA）

基本配置

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: myapp-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: myapp
  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

自定义指标

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: myapp-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: myapp
  minReplicas: 2
  maxReplicas: 10
  metrics:
    - type: Pods
      pods:
        metric:
          name: requests_per_second
        target:
          type: AverageValue
          averageValue: "100"
    - type: Object
      object:
        metric:
          name: requests_per_second
        describedObject:
          apiVersion: networking.k8s.io/v1
          kind: Ingress
          name: myapp-ingress
        target:
          type: Value
          value: "100"

行为配置

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: myapp-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: myapp
  minReplicas: 2
  maxReplicas: 10
  behavior:
    scaleUp:
      stabilizationWindowSeconds: 60
      policies:
        - type: Percent
          value: 100
          periodSeconds: 60
    scaleDown:
      stabilizationWindowSeconds: 300
      policies:
        - type: Percent
          value: 10
          periodSeconds: 60

垂直Pod自动伸缩（VPA）

安装VPA

# 安装VPA组件
kubectl apply -f https://github.com/kubernetes/autoscaler/releases/latest/download/vpa-v1-crd-gen.yaml
kubectl apply -f https://github.com/kubernetes/autoscaler/releases/latest/download/vpa-v1.yaml

VPA配置

apiVersion: autoscaling.k8s.io/v1
kind: VerticalPodAutoscaler
metadata:
  name: myapp-vpa
spec:
  targetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: myapp
  updatePolicy:
    updateMode: "Auto"
  resourcePolicy:
    containerPolicies:
      - containerName: myapp
        minAllowed:
          cpu: "100m"
          memory: "128Mi"
        maxAllowed:
          cpu: "2"
          memory: "4Gi"
        controlledResources: ["cpu", "memory"]

集群自动伸缩

安装Cluster Autoscaler

# AWS EKS
eksctl create nodegroup \
  --cluster=my-cluster \
  --name=my-nodes \
  --nodes=2 \
  --nodes-min=1 \
  --nodes-max=10 \
  --node-type=t3.medium

配置

apiVersion: apps/v1
kind: Deployment
metadata:
  name: cluster-autoscaler
  namespace: kube-system
spec:
  replicas: 1
  selector:
    matchLabels:
      app: cluster-autoscaler
  template:
    metadata:
      labels:
        app: cluster-autoscaler
    spec:
      containers:
        - name: cluster-autoscaler
          image: k8s.gcr.io/autoscaling/cluster-autoscaler:v1.25.0
          command:
            - ./cluster-autoscaler
            - --v=4
            - --cloud-provider=aws
            - --skip-nodes-with-local-storage=false
            - --expander=least-waste
            - --node-group-auto-discovery=asg:tag=k8s.io/cluster-autoscaler/enabled,k8s.io/cluster-autoscaler/my-cluster

实践：完整伸缩配置

# 1. Deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
        - name: myapp
          image: myapp:v1
          resources:
            requests:
              cpu: "100m"
              memory: "128Mi"
            limits:
              cpu: "500m"
              memory: "512Mi"

---
# 2. HPA
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: myapp-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: myapp
  minReplicas: 3
  maxReplicas: 20
  metrics:
    - type: Resource
      resource:
        name: cpu
        target:
          type: Utilization
          averageUtilization: 70

---
# 3. VPA
apiVersion: autoscaling.k8s.io/v1
kind: VerticalPodAutoscaler
metadata:
  name: myapp-vpa
spec:
  targetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: myapp
  updatePolicy:
    updateMode: "Auto"

监控伸缩

# 查看HPA状态
kubectl get hpa
kubectl describe hpa myapp-hpa

# 查看事件
kubectl get events --field-selector reason=ScalingActive

总结

自动伸缩是云原生应用的重要特性。通过HPA、VPA和Cluster Autoscaler，可以实现应用和集群的自动弹性伸缩。