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Deployment 部署

Deployment 是 Kubernetes 中最常用的资源对象，用于管理应用的部署和扩缩容。

什么是 Deployment？​

Deployment 为 Pod 和 ReplicaSet 提供声明式更新能力，是管理无状态应用的首选方式。

创建 Deployment​

基础 Deployment​

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  # Pod 副本数
  replicas: 3
  
  # 选择器
  selector:
    matchLabels:
      app: nginx
  
  # Pod 模板
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.25
        ports:
        - containerPort: 80

使用 kubectl 创建​

# 使用 YAML 创建
kubectl apply -f deployment.yaml

# 使用命令创建（不推荐用于生产）
kubectl create deployment nginx --image=nginx:1.25 --replicas=3

# 从文件模板生成
kubectl create deployment nginx --image=nginx --dry-run=client -o yaml > deployment.yaml

Deployment 策略​

RollingUpdate（滚动更新）​

默认策略，逐步替换旧版本 Pod：

spec:
  replicas: 3
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1        # 允许超过期望副本数最多1个
      maxUnavailable: 0  # 不可用的 Pod 数量（0保证服务不中断）

Recreate（重建）​

先删除所有旧 Pod，再创建新 Pod：

spec:
  replicas: 3
  strategy:
    type: Recreate

滚动更新过程：

扩缩容​

命令行扩缩容​

# 扩容到 5 个副本
kubectl scale deployment nginx-deployment --replicas=5

# 缩容到 2 个副本
kubectl scale deployment nginx-deployment --replicas=2

自动扩缩容（HPA）​

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: nginx-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: nginx-deployment
  minReplicas: 2
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 70
# 创建 HPA
kubectl apply -f hpa.yaml

# 查看 HPA 状态
kubectl get hpa

# 手动触发扩容
kubectl scale deployment nginx-deployment --replicas=5

更新 Deployment​

镜像更新​

# 更新镜像
kubectl set image deployment/nginx-deployment nginx=nginx:1.26

# 查看更新状态
kubectl rollout status deployment/nginx-deployment

# 查看历史版本
kubectl rollout history deployment/nginx-deployment

暂停和恢复​

# 暂停更新
kubectl rollout pause deployment/nginx-deployment

# 恢复更新
kubectl rollout resume deployment/nginx-deployment

回滚​

# 回滚到上一个版本
kubectl rollout undo deployment/nginx-deployment

# 回滚到指定版本
kubectl rollout undo deployment/nginx-deployment --to-revision=2

# 查看回滚状态
kubectl rollout status deployment/nginx-deployment

Deployment 生命周期​

Deployment 配置详解​

完整配置示例​

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
  namespace: production
  labels:
    app: my-app
    version: v1
spec:
  replicas: 3
  revisionHistoryLimit: 5  # 保留的历史版本数
  progressDeadlineSeconds: 600  # 最大等待时间（秒）
  
  selector:
    matchLabels:
      app: my-app
  
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
  
  template:
    metadata:
      labels:
        app: my-app
        version: v1
    spec:
      # 副本亲和性
      affinity:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 100
            podAffinityTerm:
              labelSelector:
                matchLabels:
                  app: my-app
              topologyKey: kubernetes.io/hostname
      
      containers:
      - name: app
        image: my-app:v1
        imagePullPolicy: Always
        
        ports:
        - name: http
          containerPort: 8080
          protocol: TCP
        
        # 资源配额
        resources:
          requests:
            memory: "128Mi"
            cpu: "100m"
          limits:
            memory: "256Mi"
            cpu: "500m"
        
        # 健康检查
        livenessProbe:
          httpGet:
            path: /healthz
            port: 8080
          initialDelaySeconds: 30
          periodSeconds: 10
        
        readinessProbe:
          httpGet:
            path: /ready
            port: 8080
          initialDelaySeconds: 5
          periodSeconds: 5
        
        # 环境变量
        env:
        - name: APP_ENV
          value: "production"
        
        # 卷挂载
        volumeMounts:
        - name: config
          mountPath: /app/config
      
      # 初始化容器
      initContainers:
      - name: init-db
        image: busybox:1.36
        command: ['sh', '-c', 'echo Waiting for DB']
      
      # 亲和性
      tolerations:
      - key: "dedicated"
        value: "app"
        effect: NoSchedule
      
      # 存储卷
      volumes:
      - name: config
        configMap:
          name: app-config
      
      # 终止GracePeriod
      terminationGracePeriodSeconds: 30

管理命令​

查看 Deployment​

# 查看 Deployment
kubectl get deployment

# 查看详细信息
kubectl describe deployment nginx-deployment

# 查看 Pod
kubectl get pods -l app=nginx

# 查看 ReplicaSet
kubectl get replicaset -l app=nginx

更新策略​

# 设置更新策略
kubectl patch deployment nginx-deployment \
  -p '{"spec":{"strategy":{"type":"Recreate"}}}'

# 设置镜像并记录
kubectl set image deployment/nginx-deployment \
  nginx=nginx:1.26 --record=true

调试​

# 查看特定版本的详情
kubectl rollout history deployment/nginx-deployment --revision=2

# 查看实时状态
kubectl rollout status -w deployment/nginx-deployment

# 进入 Pod 调试
kubectl exec -it <pod-name> -- /bin/sh

最佳实践​

1. 使用合适的副本数​

spec:
  replicas: 3  # 生产环境至少3个

2. 设置资源限制​

resources:
  requests:
    memory: "128Mi"
    cpu: "100m"
  limits:
    memory: "256Mi"
    cpu: "500m"

3. 使用探针​

livenessProbe:
  httpGet:
    path: /healthz
    port: 8080
readinessProbe:
  httpGet:
    path: /ready
    port: 8080

4. 保留历史版本​

spec:
  revisionHistoryLimit: 5

5. 使用标签管理版本​

template:
  metadata:
    labels:
      app: my-app
      version: v1.0.0

其他 Controller​

ReplicaSet​

ReplicaSet 确保指定数量的 Pod 副本运行：

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: my-replicaset
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    # ... Pod 模板

StatefulSet​

用于有状态应用：

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql
spec:
  serviceName: mysql
  replicas: 3
  selector:
    matchLabels:
      app: mysql
  template:
    # ... Pod 模板
  volumeClaimTemplates:
  - metadata:
      name: data
    spec:
      accessModes: ["ReadWriteOnce"]
      resources:
        requests:
          storage: 10Gi

DaemonSet​

确保每个节点都运行一个 Pod：

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: logging-agent
spec:
  selector:
    matchLabels:
      app: logging
  template:
    # ... Pod 模板

小结​

本章我们学习了：

  1. Deployment 概念：声明式管理 Pod
  2. 创建 Deployment：YAML 配置和命令
  3. 更新策略：RollingUpdate 和 Recreate
  4. 扩缩容：手动和自动（HPA）
  5. 更新和回滚：版本管理
  6. 最佳实践：资源限制、健康检查、历史版本

练习​

  1. 创建一个包含 3 个副本的 Deployment
  2. 使用 kubectl 扩缩容
  3. 更新镜像版本并观察滚动更新过程
  4. 回滚到上一个版本

准备好继续学习了吗？点击下一章了解 Service 和网络！