Managing automatic boot source updates¶

You can manage automatic updates for boot sources used to create virtual machines. This includes configuring update behavior for Red Hat and custom boot sources.

Managing automatic updates for all system-defined boot sources¶

Disabling automatic boot source imports and updates can lower resource usage. In disconnected environments, disabling automatic boot source updates prevents CDIDataImportCronOutdated alerts from filling up logs.

To disable automatic updates for all system-defined boot sources, set the enableCommonBootImageImport field value to false. Disabling automatic updates deletes the associated DataImportCron objects. Setting this value to true turns automatic updates back on.

Prerequisites

• You have installed the OpenShift CLI (oc).

Procedure

• Enable or disable automatic boot source updates by editing the HyperConverged custom resource (CR).
  • To disable automatic boot source updates, set the spec.enableCommonBootImageImport field value in the HyperConverged CR to false. For example:
    terminal

    $ oc patch hyperconvergeds.v1beta1.hco.kubevirt.io kubevirt-hyperconverged -n openshift-cnv \
      --type json -p '[{"op": "replace", "path": \
      "/spec/enableCommonBootImageImport", \
      "value": false}]'

  • To re-enable automatic boot source updates, set the spec.enableCommonBootImageImport field value in the HyperConverged CR to true. For example:
    terminal

    $ oc patch hyperconvergeds.v1beta1.hco.kubevirt.io kubevirt-hyperconverged -n openshift-cnv \
      --type json -p '[{"op": "replace", "path": \
      "/spec/enableCommonBootImageImport", \
      "value": true}]'

Configuring the default and virt-default storage classes¶

A storage class determines how persistent storage is provisioned for workloads. In OpenShift Virtualization, the virt-default storage class takes precedence over the cluster default storage class and is used specifically for virtualization workloads.

Only one storage class should be set as virt-default or cluster default at a time. If multiple storage classes are marked as default, the virt-default storage class overrides the cluster default. To ensure consistent behavior, configure only one storage class as the default for virtualization workloads.

Prerequisites

• You have installed the OpenShift CLI (oc).

Procedure

1. Patch the current virt-default or a cluster default storage class to false:
   1. Identify all storage classes currently marked as virt-default by running the following command:
      terminal

      $ oc get sc -o json| jq '.items[].metadata|select(.annotations."storageclass.kubevirt.io/is-default-virt-class"=="true")|.name'

   2. For each storage class returned, remove the virt-default annotation by running the following command:
      terminal

      $ oc patch storageclass <storage_class_name> -p '{"metadata": {"annotations": {"storageclass.kubevirt.io/is-default-virt-class": "false"}}}'

   3. Identify all storage classes currently marked as cluster default by running the following command:
      terminal

      $ oc get sc -o json| jq '.items[].metadata|select(.annotations."storageclass.kubernetes.io/is-default-class"=="true")|.name'

   4. For each storage class returned, remove the cluster default annotation by running the following command:
      terminal

      $ oc patch storageclass <storage_class_name> -p '{"metadata": {"annotations": {"storageclass.kubernetes.io/is-default-class": "false"}}}'

2. Set a new default storage class:
   1. Assign the virt-default role to a storage class by running the following command:
      terminal

      $ oc patch storageclass <storage_class_name> -p '{"metadata": {"annotations": {"storageclass.kubevirt.io/is-default-virt-class": "true"}}}'

   2. Alternatively, assign the cluster default role to a storage class by running the following command:
      terminal

      $ oc patch storageclass <storage_class_name> -p '{"metadata": {"annotations": {"storageclass.kubernetes.io/is-default-class": "true"}}}'

Configuring a storage class for boot source images¶

You can configure a specific storage class in the HyperConverged resource.

Prerequisites

• You have installed the OpenShift CLI (oc).

Procedure

1. Open the HyperConverged CR in your default editor by running the following command:
   terminal

   $ oc edit hyperconvergeds.v1beta1.hco.kubevirt.io kubevirt-hyperconverged -n openshift-cnv

2. Add the dataImportCronTemplate to the spec section of the HyperConverged resource and set the storageClassName:
   yaml

   apiVersion: hco.kubevirt.io/v1beta1
   kind: HyperConverged
   metadata:
     name: kubevirt-hyperconverged
   spec:
     dataImportCronTemplates:
     - metadata:
         name: rhel9-image-cron
       spec:
         template:
           spec:
             storage:
               storageClassName: <storage_class>
         schedule: "0 */12 * * *"
         managedDataSource: <data_source>
   # ...

   • spec.dataImportCronTemplates.spec.template.spec.storage.storageClassName specifies the storage class.
   • spec.dataImportCronTemplates.spec.schedule is a required field that specifies the schedule for the job in cron format.
   • spec.dataImportCronTemplates.spec.managedDataSource is a required field that specifies the data source to use.
     Note

     For the custom image to be detected as an available boot source, the value of the spec.dataVolumeTemplates.spec.sourceRef.name parameter in the VM template must match this value.

3. Wait for the HyperConverged Operator (HCO) and Scheduling, Scale, and Performance (SSP) resources to complete reconciliation.
4. Delete any outdated DataVolume and VolumeSnapshot objects from the openshift-virtualization-os-images namespace by running the following command.
   terminal

   $ oc delete DataVolume,VolumeSnapshot -n openshift-virtualization-os-images --selector=cdi.kubevirt.io/dataImportCron

5. Wait for all DataSource objects to reach a "Ready - True" status. Data sources can reference either a PersistentVolumeClaim (PVC) or a VolumeSnapshot. To check the expected source format, run the following command:
   terminal

   $ oc get storageprofile <storage_class_name> -o json | jq .status.dataImportCronSourceFormat

Enabling automatic updates for custom boot sources¶

OpenShift Virtualization automatically updates system-defined boot sources by default, but does not automatically update custom boot sources. You must manually enable automatic updates by editing the HyperConverged custom resource (CR).

Prerequisites

• The cluster has a default storage class.
• You have installed the OpenShift CLI (oc).

Procedure

1. Open the HyperConverged CR in your default editor by running the following command:
   terminal

   $ oc edit hyperconvergeds.v1beta1.hco.kubevirt.io kubevirt-hyperconverged -n openshift-cnv

2. Edit the HyperConverged CR, adding the appropriate template and boot source in the dataImportCronTemplates section. For example:
   yaml

   apiVersion: hco.kubevirt.io/v1beta1
   kind: HyperConverged
   metadata:
     name: kubevirt-hyperconverged
   spec:
     dataImportCronTemplates:
     - metadata:
         name: centos-stream9-image-cron
         annotations:
           cdi.kubevirt.io/storage.bind.immediate.requested: "true"
       spec:
         schedule: "0 */12 * * *"
         template:
           spec:
             source:
               registry:
                 url: docker://quay.io/containerdisks/centos-stream:9
             storage:
               resources:
                 requests:
                   storage: 30Gi
         garbageCollect: Outdated
         managedDataSource: centos-stream9

   • spec.dataImportCronTemplates.metadata.annotations specifies a required annotation for storage classes with volumeBindingMode set to WaitForFirstConsumer.
   • spec.dataImportCronTemplates.spec.schedule specifies the schedule for the job, specified in cron format.
   • spec.dataImportCronTemplates.spec.template.spec.source.registry specifies the registry source to use to create a data volume. Use the default pod pullMethod and not node pullMethod, which is based on the node docker cache. The node docker cache is useful when a registry image is available via Container.Image, but the CDI importer is not authorized to access it.
   • spec.dataImportCronTemplates.spec.managedDataSource specifies the name of the managed data source. For the custom image to be detected as an available boot source, the name of the image’s managedDataSource must match the name of the template’s DataSource, which is found under spec.dataVolumeTemplates.spec.sourceRef.name in the VM template YAML file.
3. Save the file.

Enabling volume snapshot boot sources¶

You can enable volume snapshot boot sources by setting the parameter in the StorageProfile associated with the storage class that stores operating system base images.

Although DataImportCron was originally designed to maintain only PVC sources, VolumeSnapshot sources scale better than PVC sources for certain storage types.

Prerequisites

• You must have access to a volume snapshot with the operating system image.
• The storage must support snapshotting.
• You have installed the OpenShift CLI (oc).

Procedure

1. Open the storage profile object that corresponds to the storage class used to provision boot sources by running the following command:
   terminal

   $ oc edit storageprofile <storage_class>

2. Review the dataImportCronSourceFormat specification of the StorageProfile to confirm whether or not the VM is using PVC or volume snapshot by default.
3. Edit the storage profile, if needed, by updating the dataImportCronSourceFormat specification to snapshot.

   Example storage profile:

   yaml

   apiVersion: cdi.kubevirt.io/v1beta1
   kind: StorageProfile
   metadata:
   # ...
   spec:
     dataImportCronSourceFormat: snapshot

Verification

1. Open the storage profile object that corresponds to the storage class used to provision boot sources.
   terminal

   $ oc get storageprofile <storage_class>  -oyaml

2. Confirm that the dataImportCronSourceFormat specification of the StorageProfile is set to 'snapshot', and that any DataSource objects that the DataImportCron points to now reference volume snapshots.

You can now use these boot sources to create virtual machines.

Disabling automatic updates for a single boot source¶

You can disable automatic updates for an individual boot source, whether it is custom or system-defined, by editing the HyperConverged custom resource (CR).

Prerequisites

• You have installed the OpenShift CLI (oc).

Procedure

1. Open the HyperConverged CR in your default editor by running the following command:
   terminal

   $ oc edit hyperconvergeds.v1beta1.hco.kubevirt.io kubevirt-hyperconverged -n openshift-cnv

2. Disable automatic updates for an individual boot source by editing the spec.dataImportCronTemplates field.

   Custom boot source

   • Remove the boot source from the spec.dataImportCronTemplates field. Automatic updates are disabled for custom boot sources by default.

   System-defined boot source

   1. Add the boot source to spec.dataImportCronTemplates.

   Note

   Automatic updates are enabled by default for system-defined boot sources, but these boot sources are not listed in the CR unless you add them.

   1. Set the value of the dataimportcrontemplate.kubevirt.io/enable annotation to 'false'.

   For example:

   yaml

   apiVersion: hco.kubevirt.io/v1beta1
   kind: HyperConverged
   metadata:
     name: kubevirt-hyperconverged
   spec:
     dataImportCronTemplates:
     - metadata:
         annotations:
           dataimportcrontemplate.kubevirt.io/enable: 'false'
         name: rhel8-image-cron
   # ...

3. Save the file.

Increasing boot source disk image retention¶

You can configure image retention settings to increase the number of older operating system image versions preserved on the cluster.

When automatic boot source updates are enabled, the Containerized Data Importer (CDI) tracks and downloads the latest versions of operating system images. By default, the system aggressively minimizes the retention of older versions to conserve disk space. However, if you require a safety mechanism that allows you to roll back if a newly imported version introduces issues, you can increase the retention count.

Procedure

1. Open the HyperConverged custom resource (CR) in your default editor:
   terminal

   $ oc edit hyperconverged kubevirt-hyperconverged -n openshift-cnv

2. Edit the spec.dataImportCronTemplates field to adjust the importsToKeep parameter to your preferred retention threshold:
   yaml

   apiVersion: hco.kubevirt.io/v1beta1
   kind: HyperConverged
   metadata:
     name: kubevirt-hyperconverged
   spec:
     dataImportCronTemplates:
       - metadata:
           name: rhel9-image-cron
         spec:
           garbageCollect: Outdated (1)
           importsToKeep: 3
           schedule: "0 */12 * * *"
           managedDataSource: rhel9

Verifying the status of a boot source¶

You can determine if a boot source is system-defined or custom by viewing the HyperConverged custom resource (CR).

Prerequisites

• You have installed the OpenShift CLI (oc).

Procedure

1. View the contents of the HyperConverged CR by running the following command:
   terminal

   $ oc get hyperconvergeds.v1beta1.hco.kubevirt.io kubevirt-hyperconverged -n openshift-cnv -o yaml

   Example output:

   yaml

   apiVersion: hco.kubevirt.io/v1beta1
   kind: HyperConverged
   metadata:
     name: kubevirt-hyperconverged
   spec:
   # ...
   status:
   # ...
     dataImportCronTemplates:
     - metadata:
         annotations:
           cdi.kubevirt.io/storage.bind.immediate.requested: "true"
         name: centos-9-image-cron
       spec:
         garbageCollect: Outdated
         managedDataSource: centos-stream9
         schedule: 55 8/12 * * *
         template:
           metadata: {}
           spec:
             source:
               registry:
                 url: docker://quay.io/containerdisks/centos-stream:9
             storage:
               resources:
                 requests:
                   storage: 30Gi
           status: {}
       status:
         commonTemplate: true
   # ...
     - metadata:
         annotations:
           cdi.kubevirt.io/storage.bind.immediate.requested: "true"
         name: user-defined-dic
       spec:
         garbageCollect: Outdated
         managedDataSource: user-defined-centos-stream9
         schedule: 55 8/12 * * *
         template:
           metadata: {}
           spec:
             source:
               registry:
                 pullMethod: node
                 url: docker://quay.io/containerdisks/centos-stream:9
             storage:
               resources:
                 requests:
                   storage: 30Gi
           status: {}
       status: {}
   # ...

   • status.dataImportCronTemplates.status.commonTemplate specifies a system-defined boot source.
   • status.dataImportCronTemplates.status specifies a custom boot source.
2. Verify the status of the boot source by reviewing the status.dataImportCronTemplates.status field.
   • If the field contains commonTemplate: true, it is a system-defined boot source.
   • If the status.dataImportCronTemplates.status field has the value {}, it is a custom boot source.