09-Linux与容器化

9. Linux与容器化

9.1 核心知识点

Linux基础命令

文件操作：ls, cd, pwd, mkdir, rm, cp, mv, touch
文件查看：cat, less, head, tail, grep
文件权限：chmod, chown
进程管理：ps, top, kill, pkill
网络命令：ping, netstat, curl, wget
系统信息：uname, df, du, free

Docker基础

docker build -t myapp:1.0 .
docker run -d -p 8080:8080 --name myapp myapp:1.0
docker ps
docker logs myapp
docker exec -it myapp /bin/bash
docker stop myapp
docker rm myapp
docker rmi myapp:1.0

Dockerfile

FROM golang:1.21-alpine AS builder
WORKDIR /app
COPY . .
RUN go build -o main .
 
FROM alpine:latest
WORKDIR /root/
COPY --from=builder /app/main .
EXPOSE 8080
CMD ["./main"]

Kubernetes基础

kubectl get pods
kubectl get services
kubectl get deployments
kubectl apply -f deployment.yaml
kubectl logs -f pod-name
kubectl exec -it pod-name -- /bin/bash
kubectl scale deployment myapp --replicas=3
kubectl delete pod pod-name

Kubernetes资源

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:1.0
        ports:
        - containerPort: 8080
 
Service:
apiVersion: v1
kind: Service
metadata:
  name: myapp-service
spec:
  selector:
    app: myapp
  ports:
  - port: 80
    targetPort: 8080
  type: LoadBalancer
 
ConfigMap:
apiVersion: v1
kind: ConfigMap
metadata:
  name: myapp-config
data:
  database.url: "postgres://localhost:5432/mydb"
  cache.enabled: "true"
 
Secret:
apiVersion: v1
kind: Secret
metadata:
  name: myapp-secret
type: Opaque
data:
  password: cGFzc3dvcmQ=

9.2 常见面试题

Q1: 如何编写高效的Dockerfile？

解题思路：

1. 说明Dockerfile的最佳实践
2. 解释多阶段构建的优势
3. 演示如何优化镜像大小
4. 说明如何利用Docker缓存

代码实现：

FROM golang:1.21-alpine AS builder
 
WORKDIR /app
 
COPY go.mod go.sum ./
RUN go mod download
 
COPY . .
 
RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o main .
 
FROM alpine:latest
 
RUN apk --no-cache add ca-certificates
 
WORKDIR /root/
 
COPY --from=builder /app/main .
 
EXPOSE 8080
 
CMD ["./main"]

常见错误分析：

• 错误1：不使用多阶段构建导致镜像过大
• 错误2：COPY顺序不当导致缓存失效
• 错误3：忘记设置EXPOSE端口

Q2: Kubernetes的Deployment和StatefulSet有什么区别？

解题思路：

1. 解释Deployment的基本特性（无状态应用）
2. 解释StatefulSet的基本特性（有状态应用）
3. 对比两者的适用场景
4. 说明StatefulSet的稳定网络标识和持久化存储

代码实现：

Deployment（无状态应用）：
apiVersion: apps/v1
kind: Deployment
metadata:
  name: webapp
spec:
  replicas: 3
  selector:
    matchLabels:
      app: webapp
  template:
    metadata:
      labels:
        app: webapp
    spec:
      containers:
      - name: webapp
        image: webapp:1.0
        ports:
        - containerPort: 8080
 
StatefulSet（有状态应用）：
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql
spec:
  serviceName: mysql
  replicas: 3
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: mysql:8.0
        ports:
        - containerPort: 3306
          name: mysql
        volumeMounts:
        - name: mysql-persistent-storage
          mountPath: /var/lib/mysql
  volumeClaimTemplates:
  - metadata:
      name: mysql-persistent-storage
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 10Gi

常见错误分析：

• 错误1：混淆Deployment和StatefulSet的适用场景
• 错误2：StatefulSet忘记配置serviceName
• 错误3：不理解StatefulSet的有序部署和扩展

Q3: 如何在Kubernetes中实现配置管理？

解题思路：

1. 说明ConfigMap和Secret的用途
2. 演示如何创建ConfigMap和Secret
3. 说明如何在Pod中使用ConfigMap和Secret
4. 展示如何实现配置的热更新

代码实现：

ConfigMap（非敏感配置）：
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  app.properties: |
    server.port=8080
    database.url=postgres://localhost:5432/mydb
    cache.enabled=true
  log-level: "info"
 
Secret（敏感配置）：
apiVersion: v1
kind: Secret
metadata:
  name: app-secret
type: Opaque
data:
  database-password: cGFzc3dvcmQxMjM=
  api-key: YXBpLWtleS0xMjM0NTY3ODkw
 
使用ConfigMap和Secret：
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:1.0
        env:
        - name: LOG_LEVEL
          valueFrom:
            configMapKeyRef:
              name: app-config
              key: log-level
        - name: DATABASE_PASSWORD
          valueFrom:
            secretKeyRef:
              name: app-secret
              key: database-password
        volumeMounts:
        - name: config-volume
          mountPath: /etc/config
      volumes:
      - name: config-volume
        configMap:
          name: app-config

常见错误分析：

• 错误1：在Secret中存储明文密码
• 错误2：ConfigMap和Secret的value需要base64编码
• 错误3：不理解配置更新的传播机制