k8s Error: failed to prepare subPath for volumeMount "custom-logo" of container "grafana"

前言

使用 k8s 挂载卷文件时，使用了 hostPath，type: File

 volumeMounts:
        - mountPath: /usr/share/grafana/public/img/grafana_icon.svg
          name: custom-logo
          subPath: grafana_icon.svg
 volumes:
      - hostPath:
          path: /root/test/logo.svg
          type: File
        name: custom-logo

结果报错，kubectl describe pod：

Error: failed to prepare subPath for volumeMount "volume-mount-name" of container "container-name"

报错原因为找不到 subPath，随后使用了 initContainers，在 busybox 镜像的 mkdir 命令初始化创建该目录：

apiVersion: apps/v1
kind: Deployment
metadata:
  name: grafana
spec:
  replicas: 1
  selector:
    matchLabels:
      app: grafana
  template:
    metadata:
      labels:
        app: grafana
    spec:
      initContainers:
      - name: create-directories
        image: busybox
        command: ['sh', '-c', 'mkdir -p /usr/share/grafana/public/img']
        volumeMounts:
        - name: custom-logo
          mountPath: /usr/share/grafana/public/img
      containers:
      - name: grafana
        image: grafana/grafana:latest
        ports:
        - containerPort: 3000
        volumeMounts:
        - name: custom-logo
          mountPath: /usr/share/grafana/public/img/grafana_icon.svg
          subPath: grafana_icon.svg
      volumes:
      - name: custom-logo
        hostPath:
          path: /root/test/logo.svg

这时 pod 状态为 Init:CrashLoopBackOff，而 kubectl describe pod，报错 Back-off restarting failed container，索性就不使用 subPath 了。

最终写法

 volumeMounts:
        - mountPath: /usr/share/grafana/public/img/grafana_icon.svg
          name: custom-logo
 volumes:
      - hostPath:
          path: /root/test/logo.svg
          type: File
        name: custom-logo

成功挂载使用了 /root/test/logo.svg 文件。