Spring Boot 4教程 / 第 130 节

第13章：Docker 与 Kubernetes 集成

本章概述

Spring Boot 4 改进了容器化支持，提供更好的 Docker 和 Kubernetes 集成。

本章重点:

✅ 容器镜像构建改进
✅ Kubernetes 原生支持
✅ 健康检查与就绪探针
✅ ConfigMap 和 Secret 集成

13.1 Docker 镜像构建

13.1.1 使用 Buildpacks

Maven 插件:

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <configuration>
        <image>
            <name>myapp:${project.version}</name>
            <builder>paketobuildpacks/builder:base</builder>
        </image>
    </configuration>
</plugin>

构建命令:

# 构建 Docker 镜像
./mvnw spring-boot:build-image

# 运行容器
docker run -p 8080:8080 myapp:1.0.0

13.1.2 多阶段构建

Dockerfile:

# Stage 1: Build
FROM eclipse-temurin:21-jdk AS builder
WORKDIR /app
COPY . .
RUN ./mvnw clean package -DskipTests

# Stage 2: Runtime
FROM eclipse-temurin:21-jre
WORKDIR /app
COPY --from=builder /app/target/*.jar app.jar

# 使用虚拟线程
ENV JAVA_OPTS="-XX:+UseVirtualThreads"

EXPOSE 8080
ENTRYPOINT ["java", "-jar", "app.jar"]

镜像大小对比:

方式	镜像大小	启动时间
传统 JRE	250MB	2.5s
JRE + 优化	180MB	1.2s
Native Image	60MB	0.05s

13.2 Kubernetes 集成

13.2.1 Deployment 配置

deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: springboot4-app
spec:
  replicas: 3
  selector:
    matchLabels:
      app: springboot4-app
  template:
    metadata:
      labels:
        app: springboot4-app
    spec:
      containers:
      - name: app
        image: myapp:1.0.0
        ports:
        - containerPort: 8080
        
        # 环境变量
        env:
        - name: SPRING_PROFILES_ACTIVE
          value: "production"
        - name: JAVA_OPTS
          value: "-XX:+UseVirtualThreads -Xmx512m"
        
        # 资源限制
        resources:
          requests:
            memory: "256Mi"
            cpu: "250m"
          limits:
            memory: "512Mi"
            cpu: "500m"
        
        # 健康检查
        livenessProbe:
          httpGet:
            path: /actuator/health/liveness
            port: 8080
          initialDelaySeconds: 30
          periodSeconds: 10
        
        # 就绪探针
        readinessProbe:
          httpGet:
            path: /actuator/health/readiness
            port: 8080
          initialDelaySeconds: 20
          periodSeconds: 5
        
        # 启动探针
        startupProbe:
          httpGet:
            path: /actuator/health/startup
            port: 8080
          failureThreshold: 30
          periodSeconds: 2

13.2.2 Service 配置

service.yaml:

apiVersion: v1
kind: Service
metadata:
  name: springboot4-service
spec:
  selector:
    app: springboot4-app
  ports:
  - protocol: TCP
    port: 80
    targetPort: 8080
  type: LoadBalancer

13.2.3 ConfigMap 集成

configmap.yaml:

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  application.yml: |
    spring:
      application:
        name: springboot4-app
      threads:
        virtual:
          enabled: true
      datasource:
        url: jdbc:mysql://mysql-service:3306/mydb

使用 ConfigMap:

# 在 Deployment 中挂载
volumes:
- name: config
  configMap:
    name: app-config
volumeMounts:
- name: config
  mountPath: /config
  readOnly: true

application.yml:

spring:
  config:
    import: "optional:configtree:/config/"

13.3 健康检查

13.3.1 Kubernetes 探针配置

application.yml:

management:
  endpoint:
    health:
      probes:
        enabled: true
      group:
        liveness:
          include: livenessState
        readiness:
          include: readinessState,db
  
  health:
    livenessState:
      enabled: true
    readinessState:
      enabled: true

13.3.2 自定义健康检查

CustomHealthIndicator.java:

@Component
public class K8sHealthIndicator implements HealthIndicator {
    
    @Override
    public Health health() {
        // 检查应用状态
        boolean healthy = checkApplicationHealth();
        
        if (healthy) {
            return Health.up()
                .withDetail("kubernetes", "ready")
                .withDetail("virtualThreads", Thread.currentThread().isVirtual())
                .build();
        }
        
        return Health.down()
            .withDetail("reason", "Application not ready")
            .build();
    }
    
    private boolean checkApplicationHealth() {
        // 健康检查逻辑
        return true;
    }
}

13.4 Helm Chart

13.4.1 Chart 结构

springboot4-chart/
├── Chart.yaml
├── values.yaml
└── templates/
    ├── deployment.yaml
    ├── service.yaml
    ├── configmap.yaml
    └── ingress.yaml

values.yaml:

replicaCount: 3

image:
  repository: myapp
  tag: "1.0.0"
  pullPolicy: IfNotPresent

service:
  type: LoadBalancer
  port: 80

resources:
  limits:
    cpu: 500m
    memory: 512Mi
  requests:
    cpu: 250m
    memory: 256Mi

autoscaling:
  enabled: true
  minReplicas: 2
  maxReplicas: 10
  targetCPUUtilizationPercentage: 80

13.5 最佳实践

13.5.1 优化建议

使用虚拟线程: 减少资源占用
合理设置资源限制: 避免 OOM
配置健康检查: 确保高可用
使用 ConfigMap: 外部化配置
启用 HPA: 自动扩缩容

13.5.2 监控集成

prometheus-config.yaml:

apiVersion: v1
kind: ConfigMap
metadata:
  name: prometheus-config
data:
  prometheus.yml: |
    scrape_configs:
    - job_name: 'springboot4-app'
      kubernetes_sd_configs:
      - role: pod
      relabel_configs:
      - source_labels: [__meta_kubernetes_pod_label_app]
        action: keep
        regex: springboot4-app
      - source_labels: [__meta_kubernetes_pod_ip]
        target_label: __address__
        replacement: $1:8080
      metrics_path: /actuator/prometheus

13.6 小结

✅ Docker 集成

Buildpacks 简化构建
多阶段构建优化镜像

✅ Kubernetes 支持

原生健康检查
ConfigMap 集成
Helm Chart 部署

✅ 最佳实践

资源优化
监控集成
自动扩缩容

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