Kubernetes进阶：高级调度策略

调度策略概述

Kubernetes调度器负责将Pod分配到合适的Node节点。

节点亲和性

apiVersion: v1
kind: Pod
metadata:
  name: with-affinity
spec:
  affinity:
    nodeAffinity:
      # 必须满足
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
          - matchExpressions:
              - key: disktype
                operator: In
                values:
                  - ssd
      
      # 尽量满足
      preferredDuringSchedulingIgnoredDuringExecution:
        - weight: 1
          preference:
            matchExpressions:
              - key: region
                operator: In
                values:
                  - us-west-2

Pod亲和性和反亲和性

apiVersion: v1
kind: Pod
metadata:
  name: with-pod-affinity
spec:
  affinity:
    podAffinity:
      # 与带有cache=true标签的Pod放在同一节点
      requiredDuringSchedulingIgnoredDuringExecution:
        - labelSelector:
            matchExpressions:
              - key: cache
                operator: In
                values:
                  - "true"
          topologyKey: kubernetes.io/hostname
    
    podAntiAffinity:
      # 不与相同应用的Pod放在同一节点
      preferredDuringSchedulingIgnoredDuringExecution:
        - weight: 100
          podAffinityTerm:
            labelSelector:
              matchExpressions:
                - key: app
                  operator: In
                  values:
                    - myapp
            topologyKey: kubernetes.io/hostname

污点和容忍

设置污点

# 添加污点
kubectl taint nodes node1 key=value:NoSchedule

# 移除污点
kubectl taint nodes node1 key=value:NoSchedule-

容忍配置

apiVersion: v1
kind: Pod
metadata:
  name: with-toleration
spec:
  tolerations:
    - key: "key1"
      operator: "Equal"
      value: "value1"
      effect: "NoSchedule"
    
    - key: "key2"
      operator: "Exists"
      effect: "NoExecute"
      tolerationSeconds: 3600

资源管理

资源请求和限制

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: "250m"      # 0.25核
              memory: "256Mi"
            limits:
              cpu: "500m"      # 0.5核
              memory: "512Mi"

ResourceQuota

apiVersion: v1
kind: ResourceQuota
metadata:
  name: compute-quota
  namespace: production
spec:
  hard:
    requests.cpu: "10"
    requests.memory: 20Gi
    limits.cpu: "20"
    limits.memory: 40Gi
    pods: "50"

LimitRange

apiVersion: v1
kind: LimitRange
metadata:
  name: default-limits
  namespace: production
spec:
  limits:
    - type: Container
      default:
        cpu: "500m"
        memory: "512Mi"
      defaultRequest:
        cpu: "100m"
        memory: "128Mi"
      max:
        cpu: "2"
        memory: "4Gi"

拓扑分布约束

apiVersion: v1
kind: Pod
metadata:
  name: topology-distributed
spec:
  topologySpreadConstraints:
    - maxSkew: 1
      topologyKey: topology.kubernetes.io/zone
      whenUnsatisfiable: DoNotSchedule
      labelSelector:
        matchLabels:
          app: myapp

实践：高可用部署

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  replicas: 5
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      affinity:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
            - weight: 100
              podAffinityTerm:
                labelSelector:
                  matchLabels:
                    app: myapp
                topologyKey: kubernetes.io/hostname
      
      topologySpreadConstraints:
        - maxSkew: 1
          topologyKey: topology.kubernetes.io/zone
          whenUnsatisfiable: DoNotSchedule
          labelSelector:
            matchLabels:
              app: myapp
      
      containers:
        - name: myapp
          image: myapp:v1
          resources:
            requests:
              cpu: "100m"
              memory: "128Mi"
            limits:
              cpu: "500m"
              memory: "512Mi"

总结

Kubernetes高级调度策略可以实现更精细的Pod调度控制，提高应用的可用性和资源利用效率。