Create a Lazy Bound Storage Class

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    The Operator requires a lazily bound storage class to function correctly. This guide describes how to configure one.

    Listing Storage Classes On Your Platform

    The first step we need to take is to list any pre-existing storage classes available on the platform:

    $ kubectl get sc
    NAME                 PROVISIONER            AGE
    standard (default)   kubernetes.io/gce-pd   47d

    In the above example the platform is Google GKE, it already has a storage provider configured. If no storage providers are configured on your system then please consult the vendor for instructions related to creating one.

    Next examine the storage class to determine whether it already makes use of lazy binding:

    $ kubectl get sc standard -o yaml
    allowVolumeExpansion: true
    apiVersion: storage.k8s.io/v1
    kind: StorageClass
    metadata:
      annotations:
        storageclass.kubernetes.io/is-default-class: "true"
      creationTimestamp: "2019-10-17T10:58:24Z"
      labels:
        addonmanager.kubernetes.io/mode: EnsureExists
        kubernetes.io/cluster-service: "true"
      name: standard
      resourceVersion: "298"
      selfLink: /apis/storage.k8s.io/v1/storageclasses/standard
      uid: 0a615775-f0cd-11e9-bc41-42010a8e00c9
    parameters:
      type: pd-standard
    provisioner: kubernetes.io/gce-pd
    reclaimPolicy: Delete
    volumeBindingMode: Immediate

    The important field is volumeBindingMode. If set to Immediate a persistent volume is created for a persistent volume claim immediately upon creation. The Operator will have no control over where it is scheduled.

    If, however, it is set to WaitForFirstConsumer then the a persistent volume isn’t created when a persistent volume claim is created. It waits until the persistent volume claim is attached to a pod and inherits its scheduling information. This storage class can be used directly by the Operator.

    Creating a Lazily-Bound Storage Class

    The exact configuration varies between Kubernetes vendors, however the process is the same. Using the standard storage class as a template we can create our own:

    apiVersion: storage.k8s.io/v1
    kind: StorageClass
    metadata:
      name: standard-lazy-bound
    provisioner: kubernetes.io/gce-pd
    parameters:
      type: pd-standard
    reclaimPolicy: Delete
    volumeBindingMode: WaitForFirstConsumer
    allowVolumeExpansion: true

    Save to a file then submit to Kubernetes:

    $ kubectl create -f my-storage-class.yaml
    storageclass.storage.k8s.io/standard-lazy-bound created