4.3. Persistent Volume Claims for Serving

Procedure

1. To enable Knative Serving to use PVCs and write to them, modify the KnativeServing custom resource (CR) to include the following YAML:

   Enabling PVCs with write access

   ...
   spec:
     config:
       features:
         "kubernetes.podspec-persistent-volume-claim": enabled
         "kubernetes.podspec-persistent-volume-write": enabled
   ...

   • The kubernetes.podspec-persistent-volume-claim extension controls whether persistent volumes (PVs) can be used with Knative Serving.
   • The kubernetes.podspec-persistent-volume-write extension controls whether PVs are available to Knative Serving with the write access.

2. To claim a PV, modify your service to include the PV configuration. For example, you might have a persistent volume claim with the following configuration:

   注記

   Use the storage class that supports the access mode you are requesting. For example, you can use the ocs-storagecluster-cephfs storage class for the ReadWriteMany access mode.

   The ocs-storagecluster-cephfs storage class is supported and comes from Red Hat OpenShift Data Foundation.

   PersistentVolumeClaim configuration

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: example-pv-claim
     namespace: my-ns
   spec:
     accessModes:
       - ReadWriteMany
     storageClassName: ocs-storagecluster-cephfs
     resources:
       requests:
         storage: 1Gi

   In this case, to claim a PV with write access, modify your service as follows:

   Knative service PVC configuration

   apiVersion: serving.knative.dev/v1
   kind: Service
   metadata:
     namespace: my-ns
   ...
   spec:
    template:
      spec:
        containers:
            ...
            volumeMounts: 

   1

   
              - mountPath: /data
                name: mydata
                readOnly: false
        volumes:
          - name: mydata
            persistentVolumeClaim: 

   2

   
              claimName: example-pv-claim
              readOnly: false 

   3

   1

   Volume mount specification.

   2

   Persistent volume claim specification.

   3

   Flag that enables read-only access.

   注記

   To successfully use persistent storage in Knative services, you need additional configuration, such as the user permissions for the Knative container user.