Automated OS image import, poll and update

CDI supports automating OS image import, poll and update, keeping OS images up-to-date according to the given schedule. On the first time a DataImportCron is scheduled, the controller will import the source image. On any following scheduled poll, if the source image digest (sha256) has updated, the controller will import it to a new PVC in the DataImportCron namespace, and update the managed DataSource to point that PVC. A garbage collector (garbageCollect: Outdated enabled by default) is responsible to keep the last importsToKeep (3 by default) imported PVCs per DataImportCron, and delete older ones.

See design doc here

apiVersion: cdi.kubevirt.io/v1beta1
kind: DataImportCron
metadata:
  name: fedora-image-import-cron
  namespace: golden-images
spec:
  template:
    spec:
      source:
        registry:
          url: "docker://quay.io/kubevirt/fedora-cloud-registry-disk-demo:latest"
          pullMethod: node
          certConfigMap: some-certs
      storage:
        resources:
          requests:
            storage: 5Gi
        storageClassName: hostpath-provisioner
  schedule: "30 1 * * 1"
  garbageCollect: Outdated
  importsToKeep: 2
  managedDataSource: fedora

A DataVolume can use a sourceRef referring to a DataSource, instead of the source, so whenever created it will use the updated referred PVC similarly to a source.PVC.

apiVersion: cdi.kubevirt.io/v1beta1
kind: DataVolume
metadata:
  name: fedora-ref
  namespace: golden-images
spec:
  sourceRef:
      kind: DataSource
      name: fedora
  storage:
    resources:
      requests:
        storage: 5Gi
    storageClassName: hostpath-provisioner

OpenShift ImageStreams

Using pullMethod: node we also support import from OpenShift imageStream instead of url:

apiVersion: cdi.kubevirt.io/v1beta1
kind: DataImportCron
metadata:
  name: rhel8-image-import-cron
  namespace: openshift-virtualization-os-images
spec:
  template:
    spec:
      source:
        registry:
          imageStream: rhel8-is
          pullMethod: node
      storage:
        resources:
          requests:
            storage: 5Gi
        storageClassName: hostpath-provisioner
  schedule: "0 0 * * 5"
  importsToKeep: 4
  managedDataSource: rhel8

Currently we assume the ImageStream is in the same namespace as the DataImportCron.

To create an ImageStream one can use for example: * oc import-image rhel8-is -n openshift-virtualization-os-images --from=registry.redhat.io/rhel8/rhel-guest-image --scheduled --confirm * oc set image-lookup rhel8-is -n openshift-virtualization-os-images

Or on CRC: * oc import-image cirros-is -n openshift-virtualization-os-images --from=kubevirt/cirros-container-disk-demo --scheduled --confirm * oc set image-lookup cirros-is -n openshift-virtualization-os-images

More information on image streams is available here and here.