非常简单的provisioner，我们可以学习下如何实现一个provisioner
    https://github.com/kubernetes-retired/external-storage/blob/master/nfs-client/cmd/nfs-client-provisioner/provisioner.go
    核心函数

    1. const (
    2.     mountPath = "/persistentvolumes"
    3. )
    5. func (p *nfsProvisioner) Provision(options controller.VolumeOptions) (*v1.PersistentVolume, error) {
    6.     if options.PVC.Spec.Selector != nil {
    7.         return nil, fmt.Errorf("claim Selector is not supported")
    8.     }
    9.     glog.V(4).Infof("nfs provisioner: VolumeOptions %v", options)
    11.     pvcNamespace := options.PVC.Namespace
    12.     pvcName := options.PVC.Name
    14.     pvName := strings.Join([]string{pvcNamespace, pvcName, options.PVName}, "-")
    16.     fullPath := filepath.Join(mountPath, pvName)
    17.     glog.V(4).Infof("creating path %s", fullPath)
    18.     if err := os.MkdirAll(fullPath, 0777); err != nil {
    19.         return nil, errors.New("unable to create directory to provision new pv: " + err.Error())
    20.     }
    21.     os.Chmod(fullPath, 0777)
    23.     path := filepath.Join(p.path, pvName)
    25.     pv := &v1.PersistentVolume{
    26.         ObjectMeta: metav1.ObjectMeta{
    27.             Name: options.PVName,
    28.         },
    29.         Spec: v1.PersistentVolumeSpec{
    30.             PersistentVolumeReclaimPolicy: options.PersistentVolumeReclaimPolicy,
    31.             AccessModes:                   options.PVC.Spec.AccessModes,
    32.             MountOptions:                  options.MountOptions,
    33.             Capacity: v1.ResourceList{
    34.                 v1.ResourceName(v1.ResourceStorage): options.PVC.Spec.Resources.Requests[v1.ResourceName(v1.ResourceStorage)],
    35.             },
    36.             PersistentVolumeSource: v1.PersistentVolumeSource{
    37.                 NFS: &v1.NFSVolumeSource{
    38.                     Server:   p.server,
    39.                     Path:     path,
    40.                     ReadOnly: false,
    41.                 },
    42.             },
    43.         },
    44.     }
    45.     return pv, nil
    46. }

    非常简洁，判断下目录是否存在，，如果不存在就把目录创建出来，然后把元信息返回出去就行了。