K8s共享Volume的Pod故障排查：fortune-cont容器CrashLoopBackOff

问题描述 #

实践《Kubernetes in Action》中6.1. 包含两个共享Volume的Pod: fortune-pod.yaml示例时，Pod内fortune-cont容器无法正常运行，处于CrashLoopBackOff状态。

容器日志提示 #

Defaulted container "fortune-cont" out of: fortune-cont, web-server

Pod事件 #

Events:
  Type     Reason     Age                  From               Message
  ----     ------     ----                 ----               -------
  Normal   Scheduled  40m                  default-scheduler  Successfully assigned book/vol-1-fd556f5dc-8ggj6 to minikube
  Normal   Pulled     40m                  kubelet            Container image "nginx:alpine" already present on machine
  Normal   Created    40m                  kubelet            Created container web-server
  Normal   Started    40m                  kubelet            Started container web-server
  Normal   Created    39m (x4 over 40m)    kubelet            Created container fortune-cont
  Normal   Started    39m (x4 over 40m)    kubelet            Started container fortune-cont
  Normal   Pulled     38m (x5 over 40m)    kubelet            Container image "xxxx/fortune:v1" already present on machine
  Warning  BackOff    25s (x188 over 40m)  kubelet            Back-off restarting failed container

Deployment配置 #

apiVersion: apps/v1
kind: Deployment
metadata:
  name: vol-1
  namespace: book
spec:
  replicas: 1
  selector:
    matchLabels:
      name: fortune-vol-1
      type: volume
  template:
    metadata:
      labels:
        name: fortune-vol-1
        type: volume
    spec:
      containers:
      - image: ****/fortune:v1
        name: fortune-cont
        volumeMounts:
        - name: html 
          mountPath: /var/htdocs
      - image: nginx:alpine
        name: web-server
        volumeMounts:
        - name: html
          mountPath: /usr/share/nginx/html
          readOnly: true
        ports:
        - containerPort: 80
          protocol: TCP
      volumes:
        - name: html
          emptyDir: {}

Pod关键状态信息 #

Containers:
  fortune-cont:
    Image:          prav33n/fortune:v1
    State:          Waiting
      Reason:       CrashLoopBackOff
    Last State:     Terminated
      Reason:       Completed
      Exit Code:    0
    Restart Count:  17
    Mounts:
      /var/htdocs from html (rw)
  web-server:
    State:          Running
    Ready:          True

问题根源 #

fortune-cont容器退出码为0（正常退出），但容器启动后立即完成一次性任务并退出，Kubernetes会因容器退出反复重启它，进而触发CrashLoopBackOff。这是因为当前镜像仅执行单次fortune命令，而非保持长期运行的进程，不符合Kubernetes对容器持续运行的要求。

解决步骤 #

1. 修改容器启动命令，维持进程持续运行 #

更新Deployment中fortune-cont的配置，添加循环命令定期生成文件并保持容器存活：

containers:
- image: prav33n/fortune:v1
  name: fortune-cont
  command: ["/bin/sh"]
  args: ["-c", "while true; do fortune > /var/htdocs/index.html; sleep 30; done"]
  volumeMounts:
  - name: html 
    mountPath: /var/htdocs

该配置会让容器每隔30秒生成新的fortune文本到共享Volume的index.html文件中，同时保持进程持续运行。

2. 应用配置更新 #

执行命令生效修改：

kubectl apply -f <你的Deployment文件名>.yaml -n book

3. 验证Pod状态 #

等待片刻后检查Pod状态：

kubectl get pods -n book

确认fortune-cont容器状态变为Running，Pod整体状态变为Ready。

4. 验证功能 #

通过端口转发访问Nginx服务，确认能看到生成的fortune文本：

# 替换<pod-name>为实际Pod名称
kubectl port-forward <pod-name> 8080:80 -n book
# 用curl访问或打开浏览器访问 http://localhost:8080
curl http://localhost:8080

补充说明 #

如果prav33n/fortune:v1镜像未包含fortune命令或sh终端，需先检查镜像内容，或参考《Kubernetes in Action》示例，基于alpine镜像安装fortune包并编写启动脚本构建镜像。

内容的提问来源于stack exchange，提问作者Praveen