kubernetes - 无法跨 n 个部署副本挂载只读 Kubernetes 持久卷

Question

我从 gcePersistentDisk 创建了一个 Kubernetes 只读多持久卷，如下所示:

apiVersion: v1
kind: PersistentVolume
metadata:
    name: ferret-pv-1
spec:
    capacity:
    storage: 500Gi
    accessModes:
      - ReadOnlyMany
    persistentVolumeReclaimPolicy: Retain
    gcePersistentDisk:
      pdName: data-1
      partition: 1
      fsType: ext4

它从现有的 gcePersistentDisk 分区创建持久卷，该分区上已经有一个 ext4 文件系统:

$ kubectl get pv
NAME          CAPACITY   ACCESSMODES   RECLAIMPOLICY   STATUS    CLAIM                    REASON    AGE
ferret-pv-1   500Gi      ROX           Retain          Bound     default/ferret-pvc             5h

然后我创建一个 Kubernetes 只读多持久卷声明，如下所示:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: ferret-pvc
spec:
  accessModes:
    - ReadOnlyMany
  resources:
    requests:
      storage: 500Gi

它绑定(bind)到我在上面创建的只读 PV:

$ kubectl get pvc
NAME         STATUS    VOLUME        CAPACITY   ACCESSMODES   AGE
ferret-pvc   Bound     ferret-pv-1   500Gi      ROX           5h

然后，我使用刚刚创建的 PVC 创建一个包含 2 个副本的 Kubernetes 部署，如下所示:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: ferret2-deployment
spec:
  replicas: 2
  template:
    metadata:
      labels:
        name: ferret2
    spec:
      containers:
      - image: us.gcr.io/centered-router-102618/ferret2
        name: ferret2
        ports:
        - name: fjds
          containerPort: 1004
          hostPort: 1004
        volumeMounts:
          - name: ferret-pd
            mountPath: /var/ferret
            readOnly: true
      volumes:
          - name: ferret-pd
            persistentVolumeClaim:
              claimName: ferret-pvc

部署已创建:

$ kubectl get deployments
NAME                 DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
ferret2-deployment   2         2         2            1           4h

但是，当我从部署中查看相应的两个 pod 时，只有第一个出现:

$ kubectl get pods
NAME                                  READY     STATUS              RESTARTS   AGE
ferret2-deployment-1336109949-2rfqd   1/1       Running             0          4h
ferret2-deployment-1336109949-yimty   0/1       ContainerCreating   0          4h

查看没有出现的第二个 pod:

$ kubectl describe pod ferret2-deployment-1336109949-yimty

Events:
  FirstSeen     LastSeen        Count   From                            SubObjectPath   Type        Reason      Message
  ---------     --------        -----   ----                            -------------   --------        ------      -------
  4h        1m          128     {kubelet gke-sim-cluster-default-pool-e38a7605-kgdu}            Warning     FailedMount     Unable to mount volumes for pod "ferret2-deployment-1336109949-yimty_default(d1393a2d-9fc9-11e6-a873-42010a8a009e)": timeout expired waiting for volumes to attach/mount for pod "ferret2-deployment-1336109949-yimty"/"default". list of unattached/unmounted volumes=[ferret-pd]
  4h        1m          128     {kubelet gke-sim-cluster-default-pool-e38a7605-kgdu}            Warning     FailedSync      Error syncing pod, skipping: timeout expired waiting for volumes to attach/mount for pod "ferret2-deployment-1336109949-yimty"/"default". list of unattached/unmounted volumes=[ferret-pd]
  4h        55s         145     {controller-manager }                           Warning     FailedMount     Failed to attach volume "ferret-pv-1" on node "gke-sim-cluster-default-pool-e38a7605-kgdu" with: googleapi: Error 400: The disk resource 'data-1' is already being used by 'gke-sim-cluster-default-pool-e38a7605-fyx4'

它拒绝启动第二个 pod，因为它认为第一个 pod 独占了 PV。但是，当我登录到第一个声明 PV 的 pod 时，我看到它已将卷安装为只读:

$ kubectl exec -ti ferret2-deployment-1336109949-2rfqd -- bash
root@ferret2-deployment-1336109949-2rfqd:/opt/ferret# mount | grep ferret
/dev/sdb1 on /var/ferret type ext4 (ro,relatime,data=ordered)

我是否遗漏了有关在使用相同 PVC 的部署中跨多个 Pod 安装 PV 只读的内容？该磁盘未被任何其他容器挂载。由于它以只读方式安装在第一个 pod 上，因此我预计部署中的第二个和任何其他副本在声明/安装它时没有问题。另外 - 我如何让 ReadWriteOnce 正常工作以及如何指定哪个 pod 安装卷 rw？

Answer 1

PV/PVC 访问方式仅用于绑定(bind) PV/PVC。

在您的 pod 模板中，确保您设置了 spec.volumes.persistentVolumeClaim.readOnly至true .这可确保卷以只读模式附加。

同样在您的 pod 模板中，确保您设置了 spec.containers.volumeMounts[x].readOnly为真。这确保卷以只读模式安装。

此外，由于您正在预先配置您的 PV。确保设置为 claimRef字段，以确保没有其他 PVC 意外绑定(bind)到它。见 https://stackoverflow.com/a/34323691