PVC 可以绑定到特定的 PV 吗? [英] Can a PVC be bound to a specific PV?

问题描述

k8s 维护者在 https://github.com/kubernetes 中讨论了这个问题/kubernetes/issues/7438#issuecomment-97148195:

<块引用><块引用>

允许用户要求特定的 PV 打破了他们之间的分离

我不买那个.我们允许用户选择一个节点.这不是常见的案例，但它存在是有原因的.

结局如何?拥有 >1 PV 和 PVC 的预期方式是什么，就像 https://github.com/kubernetes/kubernetes/tree/master/examples/nfs?

我们使用 NFS，而 PersistentVolume 是一个方便的抽象，因为我们可以将 server IP 和 path 保留在那里.但是 PersistentVolumeClaim 可以获取任何足够大小的 PV，从而防止 path 重用.

可以在 PVC spec 块中设置 volumeName(参见 https://github.com/kubernetes/kubernetes/pull/7529)但没有区别.

解决方案

今天有一种方法可以将 PV 预先绑定到 PVC，下面是一个示例:

1. 创建一个 PV 对象，其 ClaimRef 字段引用您随后将创建的 PVC:

    $ kubectl create -f pv.yaml持久卷pv0003"创造

   其中 pv.yaml 包含:

    apiVersion: v1种类:持久卷元数据:名称:pv0003规格:存储类名称:"容量:存储:5Gi访问模式:- 读写一次持久卷回收策略:保留索赔参考:命名空间:默认名称:我的主张nfs:路径:/tmp服务器:172.17.0.2

2. 然后创建具有相同名称的 PVC:

    种类:PersistentVolumeClaimapi版本:v1元数据:名称:我的主张规格:存储类名称:"访问模式:- 读写一次资源:要求:存储:5Gi

3. PV 和 PVC 应该立即绑定:

    $ kubectl get pvc名称 状态 卷容量 访问模式 年龄myclaim 绑定 pv0003 5Gi RWO 4s$ ./cluster/kubectl.sh 获取 pv名称 容量 访问模式 状态 索赔 原因 年龄pv0003 5Gi RWO 绑定默认值/myclaim 57s

This was discussed by k8s maintainers in https://github.com/kubernetes/kubernetes/issues/7438#issuecomment-97148195:

Allowing users to ask for a specific PV breaks the separation between them

I don't buy that. We allow users to choose a node. It's not the common case, but it exists for a reason.

How did it end? What's the intended way to have >1 PV's and PVC's like the one in https://github.com/kubernetes/kubernetes/tree/master/examples/nfs?

We use NFS, and PersistentVolume is a handy abstraction because we can keep the server IP and the path there. But a PersistentVolumeClaim gets any PV with sufficient size, preventing path reuse.

Can set volumeName in a PVC spec block (see https://github.com/kubernetes/kubernetes/pull/7529) but it makes no difference.

解决方案

There is a way to pre-bind PVs to PVCs today, here is an example showing how:

1. Create a PV object with a ClaimRef field referencing a PVC that you will subsequently create:

    $ kubectl create -f pv.yaml
    persistentvolume "pv0003" created
   

   where pv.yaml contains:

    apiVersion: v1
    kind: PersistentVolume
    metadata:
      name: pv0003
    spec:
      storageClassName: ""
      capacity:
        storage: 5Gi
      accessModes:
        - ReadWriteOnce
      persistentVolumeReclaimPolicy: Retain
      claimRef:
        namespace: default
        name: myclaim
      nfs:
        path: /tmp
        server: 172.17.0.2
   

2. Then create the PVC with the same name:

    kind: PersistentVolumeClaim
    apiVersion: v1
    metadata:
      name: myclaim
    spec:
      storageClassName: ""
      accessModes:
        - ReadWriteOnce
      resources:
        requests:
          storage: 5Gi
   

3. The PV and PVC should be bound immediately:

    $ kubectl get pvc
    NAME      STATUS    VOLUME    CAPACITY   ACCESSMODES   AGE
    myclaim   Bound     pv0003    5Gi        RWO           4s
    $ ./cluster/kubectl.sh get pv
    NAME      CAPACITY   ACCESSMODES   STATUS    CLAIM             REASON    AGE
    pv0003    5Gi        RWO           Bound     default/myclaim             57s
   

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