简单使用

1、创建local-storage

  1. apiVersion: storage.k8s.io/v1
  2. kind: StorageClass
  3. metadata:
  4.   name: local-storage
  5. provisioner: kubernetes.io/no-provisioner
  6. reclaimPolicy: Delete
  7. volumeBindingMode: WaitForFirstConsumer

查看storageclass的状态

  1.  kubectl get sc
  2. NAME                  PROVISIONER                    RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
  3. local-storage         kubernetes.io/no-provisioner   Delete          WaitForFirstConsumer   false                  2m1s

2、创建pv，这里的pv是local pv

  1. apiVersion: v1
  2. kind: PersistentVolume
  3. metadata:
  4.   name: local-pv-sdc
  5. spec:
  6.   capacity:
  7.     storage: 4Gi
  8.   accessModes:
  9.   - ReadWriteOnce
  10.   persistentVolumeReclaimPolicy: Retain
  11.   storageClassName: local-storage
  12.   local:
  13.     path: /data/pv
  14.   nodeAffinity:
  15.     required:
  16.       nodeSelectorTerms:
  17.       - matchExpressions:
  18.         - key: node
  19.           operator: In
  20.           values:
  21.           - middleware

查看pv状态

  1. # kubectl get pv
  2. NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                     STORAGECLASS          REASON   AGE
  3. local-pv-sdc                               2Gi        RWO            Retain           Available                             local-storage                  7s

3、创建一个statefuleset应用测试

  1. apiVersion: apps/v1
  2. kind: StatefulSet
  3. metadata:
  4.   name: web
  5. spec:
  6.   serviceName: "nginx"
  7.   replicas: 2
  8.   selector:
  9.     matchLabels:
  10.       app: nginx
  11.   template:
  12.     metadata:
  13.       labels:
  14.         app: nginx
  15.         role: stateful
  16.     spec:
  17.       containers:
  18.       - name: nginx
  19.         image: cnych/nginx-slim:0.8
  20.         ports:
  21.         - containerPort: 80
  22.           name: web
  23.         volumeMounts:
  24.         - name: www
  25.           mountPath: /usr/share/nginx/html
  26.   volumeClaimTemplates:
  27.   - metadata:
  28.       name: www
  29.     spec:
  30.       accessModes: [ "ReadWriteOnce" ]
  31.       storageClassName: local-storage
  32.       resources:
  33.         requests:
  34.           storage: 1Gi

查看pvc,pv,storageclass状态

  1. # kubectl get pvc
  2. NAME                STATUS    VOLUME         CAPACITY   ACCESS MODES   STORAGECLASS    AGE
  3. www-web-0           Bound     local-pv-sdc   2Gi        RWO            local-storage   86s
  4. # kubectl get pv
  5. NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                     STORAGECLASS          REASON   AGE
  6. local-pv-sdc                               2Gi        RWO            Retain           Bound    default/www-web-0         local-storage                  6m21s

4、扩容测试

  1. # kubectl edit pvc www-web-0
  2. ...
  3. spec:
  4.   accessModes:
  5.   - ReadWriteOnce
  6.   resources:
  7.     requests:
  8.       storage: 2Gi
  9.   storageClassName: local-storage
  10.   volumeMode: Filesystem
  11.   volumeName: local-pv-sdc
  12. ...

将storage修改为2Gi，保存退出，报错如下。

  1. error: persistentvolumeclaims "www-web-0" could not be patched: persistentvolumeclaims "www-web-0" is forbidden: only dynamically provisioned pvc can be resized and the storageclass that provisions the pvc must support resize

这是说pvc必须支持修改大小，我们先修改storageclass，让其支持扩展，如下加allowVolumeExpansion: true

  1. kind: StorageClass
  2. apiVersion: storage.k8s.io/v1
  3. metadata:
  4.   name: local-storage
  5. provisioner: kubernetes.io/no-provisioner
  6. volumeBindingMode: WaitForFirstConsumer
  7. allowVolumeExpansion: true

然后我们再修改pvc，提示改成功如下：

  1. # kubectl edit pvc www-web-0 
  2. persistentvolumeclaim/www-web-0 edited

我们再修改pv的大小，修改为3G，修改后的状态如下：

  1. # kubectl get pv
  2. NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                     STORAGECLASS          REASON   AGE
  3. local-pv-sdc                               3Gi        RWO            Retain           Bound    default/www-web-0         local-storage                  28m

然后我们再扩容pvc，查看pvc的event如下：

  1. Ignoring the PVC: didn't find a plugin capable of expanding the volume; waiting for an external controller to process this PVC.

报错信息为：没有找到可扩展的插件。
我上官方网站一看，原来人家已经说的很清楚了：Although the feature is enabled by default, a cluster admin must opt-in to allow users to resize their volumes. Kubernetes v1.11 ships with volume expansion support for the following in-tree volume plugins: AWS-EBS, GCE-PD, Azure Disk, Azure File, Glusterfs, Cinder, Portworx, and Ceph RBD.