面试重要程度：⭐⭐⭐⭐⭐

常见提问方式：Kubernetes的核心组件有哪些？Pod和Container的区别？

预计阅读时间：35分钟

📋 知识点概览

Kubernetes（K8s）是容器编排领域的事实标准，掌握其核心概念和实践对于现代Java开发者至关重要。本节将深入讲解K8s架构、核心资源对象以及服务发现机制。

🏗️ Kubernetes架构详解

集群架构组件

/**
 * Kubernetes集群架构
 */
public class KubernetesArchitecture {
    
    /**
     * Master节点组件
     */
    public enum MasterComponent {
        API_SERVER("kube-apiserver", "集群的统一入口，提供RESTful API"),
        ETCD("etcd", "分布式键值存储，保存集群状态"),
        SCHEDULER("kube-scheduler", "负责Pod调度到合适的Node"),
        CONTROLLER_MANAGER("kube-controller-manager", "运行控制器进程"),
        CLOUD_CONTROLLER_MANAGER("cloud-controller-manager", "云平台相关控制器");
        
        private final String name;
        private final String description;
        
        MasterComponent(String name, String description) {
            this.name = name;
            this.description = description;
        }
    }
    
    /**
     * Node节点组件
     */
    public enum NodeComponent {
        KUBELET("kubelet", "节点代理，管理Pod生命周期"),
        KUBE_PROXY("kube-proxy", "网络代理，实现Service负载均衡"),
        CONTAINER_RUNTIME("container-runtime", "容器运行时（Docker/containerd）");
        
        private final String name;
        private final String description;
        
        NodeComponent(String name, String description) {
            this.name = name;
            this.description = description;
        }
    }
    
    /**
     * 集群网络组件
     */
    public static class NetworkComponents {
        
        public static final String[] CNI_PLUGINS = {
            "Flannel",      // 简单的overlay网络
            "Calico",       // 支持网络策略的CNI
            "Weave Net",    // 易于安装的网络方案
            "Cilium",       // 基于eBPF的高性能网络
            "Antrea"        // VMware开源的CNI插件
        };
        
        /**
         * 网络模型说明
         */
        public static void explainNetworkModel() {
            System.out.println("Kubernetes网络模型要求：");
            System.out.println("1. 每个Pod都有独立的IP地址");
            System.out.println("2. 同一Node上的Pod可以直接通信");
            System.out.println("3. 不同Node上的Pod可以直接通信（无需NAT）");
            System.out.println("4. Pod内的容器共享网络命名空间");
        }
    }
}

🚀 核心资源对象详解

Pod资源管理

# Pod配置示例
apiVersion: v1
kind: Pod
metadata:
  name: spring-boot-app
  labels:
    app: spring-boot
    version: v1.0
  annotations:
    description: "Spring Boot应用Pod"
spec:
  # 重启策略
  restartPolicy: Always
  
  # 节点选择器
  nodeSelector:
    disktype: ssd
  
  # 容器配置
  containers:
  - name: app
    image: myregistry/spring-boot-app:v1.0
    ports:
    - containerPort: 8080
      name: http
    
    # 资源限制
    resources:
      requests:
        memory: "512Mi"
        cpu: "250m"
      limits:
        memory: "1Gi"
        cpu: "500m"
    
    # 环境变量
    env:
    - name: SPRING_PROFILES_ACTIVE
      value: "prod"
    - name: DB_PASSWORD
      valueFrom:
        secretKeyRef:
          name: db-secret
          key: password
    
    # 健康检查
    livenessProbe:
      httpGet:
        path: /actuator/health
        port: 8080
      initialDelaySeconds: 30
      periodSeconds: 10
      timeoutSeconds: 5
      failureThreshold: 3
    
    readinessProbe:
      httpGet:
        path: /actuator/health/readiness
        port: 8080
      initialDelaySeconds: 5
      periodSeconds: 5
      timeoutSeconds: 3
      failureThreshold: 3
    
    # 数据卷挂载
    volumeMounts:
    - name: config-volume
      mountPath: /app/config
    - name: log-volume
      mountPath: /app/logs
  
  # 数据卷定义
  volumes:
  - name: config-volume
    configMap:
      name: app-config
  - name: log-volume
    emptyDir: {}
  
  # Init容器
  initContainers:
  - name: init-db
    image: busybox:1.35
    command: ['sh', '-c', 'until nslookup db-service; do echo waiting for db; sleep 2; done;']

Deployment控制器

/**
 * Deployment资源管理
 */
public class DeploymentManagement {
    
    /**
     * Deployment配置示例
     */
    public static String getDeploymentYaml() {
        return """
            apiVersion: apps/v1
            kind: Deployment
            metadata:
              name: spring-boot-deployment
              labels:
                app: spring-boot
            spec:
              # 副本数量
              replicas: 3
              
              # 选择器
              selector:
                matchLabels:
                  app: spring-boot
              
              # 更新策略
              strategy:
                type: RollingUpdate
                rollingUpdate:
                  maxUnavailable: 1
                  maxSurge: 1
              
              # Pod模板
              template:
                metadata:
                  labels:
                    app: spring-boot
                spec:
                  containers:
                  - name: app
                    image: myregistry/spring-boot-app:v1.0
                    ports:
                    - containerPort: 8080
                    resources:
                      requests:
                        memory: "512Mi"
                        cpu: "250m"
                      limits:
                        memory: "1Gi"
                        cpu: "500m"
                    livenessProbe:
                      httpGet:
                        path: /actuator/health
                        port: 8080
                      initialDelaySeconds: 30
                      periodSeconds: 10
                    readinessProbe:
                      httpGet:
                        path: /actuator/health/readiness
                        port: 8080
                      initialDelaySeconds: 5
                      periodSeconds: 5
            """;
    }
    
    /**
     * 滚动更新策略
     */
    public static class RollingUpdateStrategy {
        
        public static void performRollingUpdate() {
            String[] commands = {
                "# 更新镜像版本",
                "kubectl set image deployment/spring-boot-deployment app=myregistry/spring-boot-app:v2.0",
                "",
                "# 查看更新状态",
                "kubectl rollout status deployment/spring-boot-deployment",
                "",
                "# 查看更新历史",
                "kubectl rollout history deployment/spring-boot-deployment",
                "",
                "# 回滚到上一版本",
                "kubectl rollout undo deployment/spring-boot-deployment",
                "",
                "# 回滚到指定版本",
                "kubectl rollout undo deployment/spring-boot-deployment --to-revision=2",
                "",
                "# 暂停更新",
                "kubectl rollout pause deployment/spring-boot-deployment",
                "",
                "# 恢复更新",
                "kubectl rollout resume deployment/spring-boot-deployment"
            };
            
            for (String command : commands) {
                System.out.println(command);
            }
        }
    }
}

Service服务发现

# Service配置示例
apiVersion: v1
kind: Service
metadata:
  name: spring-boot-service
  labels:
    app: spring-boot
spec:
  # 服务类型
  type: ClusterIP  # ClusterIP/NodePort/LoadBalancer/ExternalName
  
  # 选择器
  selector:
    app: spring-boot
  
  # 端口配置
  ports:
  - name: http
    port: 80
    targetPort: 8080
    protocol: TCP
  
  # 会话亲和性
  sessionAffinity: ClientIP
  sessionAffinityConfig:
    clientIP:
      timeoutSeconds: 10800

---
# NodePort Service示例
apiVersion: v1
kind: Service
metadata:
  name: spring-boot-nodeport
spec:
  type: NodePort
  selector:
    app: spring-boot
  ports:
  - port: 80
    targetPort: 8080
    nodePort: 30080

---
# LoadBalancer Service示例
apiVersion: v1
kind: Service
metadata:
  name: spring-boot-lb
spec:
  type: LoadBalancer
  selector:
    app: spring-boot
  ports:
  - port: 80
    targetPort: 8080
  loadBalancerSourceRanges:
  - 10.0.0.0/8

🔧 ConfigMap和Secret管理

配置管理最佳实践

/**
 * Kubernetes配置管理
 */
public class ConfigurationManagement {
    
    /**
     * ConfigMap使用示例
     */
    public static class ConfigMapExample {