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Preparing for image-based installation for single-node OpenShift clusters

To prepare for an image-based installation for single-node OpenShift clusters, you must complete the following tasks:

  • Create a seed image by using the Lifecycle Agent.
  • Verify that all software components meet the required versions. For further information, see "Software prerequisites for an image-based installation and deployment".

Additional resources

Installing the Lifecycle Agent​

Use the Lifecycle Agent to generate a seed image from a seed cluster. You can install the Lifecycle Agent using the OpenShift CLI (oc) or the web console.

Installing the Lifecycle Agent by using the CLI​

You can use the OpenShift CLI (oc) to install the Lifecycle Agent.

Prerequisites

  • You have installed the OpenShift CLI (oc).
  • You have logged in as a user with cluster-admin privileges.

Procedure

  1. Create a Namespace object YAML file for the Lifecycle Agent:

    apiVersion: v1
    kind: Namespace
    metadata:
      name: openshift-lifecycle-agent
      annotations:
        workload.openshift.io/allowed: management
    1. Create the Namespace CR by running the following command: 
      $ oc create -f <namespace_filename>.yaml

  2. Create an OperatorGroup object YAML file for the Lifecycle Agent:

    apiVersion: operators.coreos.com/v1
    kind: OperatorGroup
    metadata:
      name: openshift-lifecycle-agent
      namespace: openshift-lifecycle-agent
    spec:
      targetNamespaces:
      - openshift-lifecycle-agent
    1. Create the OperatorGroup CR by running the following command: 
      $ oc create -f <operatorgroup_filename>.yaml

  3. Create a Subscription CR for the Lifecycle Agent:

    apiVersion: operators.coreos.com/v1alpha1
    kind: Subscription
    metadata:
      name: openshift-lifecycle-agent-subscription
      namespace: openshift-lifecycle-agent
    spec:
      channel: "stable"
      name: lifecycle-agent
      source: redhat-operators
      sourceNamespace: openshift-marketplace
    1. Create the Subscription CR by running the following command: 
      $ oc create -f <subscription_filename>.yaml

Verification

  1. To verify that the installation succeeded, inspect the CSV resource by running the following command:

    $ oc get csv -n openshift-lifecycle-agent

    Example output:

    NAME                              DISPLAY                     VERSION               REPLACES                           PHASE
    lifecycle-agent.v4.22.0           Openshift Lifecycle Agent   4.22.0                Succeeded

  2. Verify that the Lifecycle Agent is up and running by running the following command:

    $ oc get deploy -n openshift-lifecycle-agent

    Example output:

    NAME                                 READY   UP-TO-DATE   AVAILABLE   AGE
    lifecycle-agent-controller-manager   1/1     1            1           14s

Installing the Lifecycle Agent by using the web console​

You can use the OpenShift Container Platform web console to install the Lifecycle Agent.

Prerequisites

  • You have logged in as a user with cluster-admin privileges.

Procedure

  1. In the OpenShift Container Platform web console, navigate to Ecosystem → Software Catalog.
  2. Search for the Lifecycle Agent from the list of available Operators, and then click Install.
  3. On the Install Operator page, under A specific namespace on the cluster select openshift-lifecycle-agent.
  4. Click Install.

Verification

  1. To confirm that the installation is successful:

    1. Click Ecosystem → Installed Operators.

    2. Ensure that the Lifecycle Agent is listed in the openshift-lifecycle-agent project with a Status of InstallSucceeded.

      note

      During installation an Operator might display a Failed status. If the installation later succeeds with an InstallSucceeded message, you can ignore the Failed message.

If the Operator is not installed successfully:

  1. Click Ecosystem → Installed Operators, and inspect the Operator Subscriptions and Install Plans tabs for any failure or errors under Status.
  2. Click Workloads → Pods, and check the logs for pods in the openshift-lifecycle-agent project.

Configuring a shared container partition between ostree stateroots​

warning

You must complete this procedure at installation time.

Apply a MachineConfig to the seed cluster to create a separate partition and share the /var/lib/containers partition between the two ostree stateroots that will be used during the preinstall process.

Procedure

  • Apply a MachineConfig to create a separate partition:

    apiVersion: machineconfiguration.openshift.io/v1
    kind: MachineConfig
    metadata:
      labels:
        machineconfiguration.openshift.io/role: master
      name: 98-var-lib-containers-partitioned
    spec:
      config:
        ignition:
          version: 3.2.0
        storage:
          disks:
            - device: /dev/disk/by-path/<root_disk>
              partitions:
                - label: var-lib-containers
                  startMiB: <start_of_partition>
                  sizeMiB: <partition_size>
          filesystems:
            - device: /dev/disk/by-partlabel/var-lib-containers
              format: xfs
              mountOptions:
                - defaults
                - prjquota
              path: /var/lib/containers
              wipeFilesystem: true
        systemd:
          units:
            - contents: |-
                # Generated by Butane
                [Unit]
                Before=local-fs.target
                Requires=systemd-fsck@dev-disk-by\x2dpartlabel-var\x2dlib\x2dcontainers.service
                After=systemd-fsck@dev-disk-by\x2dpartlabel-var\x2dlib\x2dcontainers.service

                [Mount]
                Where=/var/lib/containers
                What=/dev/disk/by-partlabel/var-lib-containers
                Type=xfs
                Options=defaults,prjquota

                [Install]
                RequiredBy=local-fs.target
              enabled: true
              name: var-lib-containers.mount

    where:

    <root_disk>
    Specifies the root disk, for example pci-0000:01:00.0-scsi-0:2:0:0.
    <start_of_partition>
    Specifies the start of the partition in MiB. If the value is too small, the installation will fail.
    <partition_size>
    Specifies a minimum size for the partition of 500 GB (512000 MiB) to ensure adequate disk space for precached images. If the value is too small, the deployments after installation will fail.

Seed image configuration​

You can create a seed image from a single-node OpenShift cluster with the same hardware as your bare-metal host, and with a similar target cluster configuration. However, the seed image generated from the seed cluster cannot contain any cluster-specific configuration.

The following table lists the components, resources, and configurations that you must and must not include in your seed image:

Seed image configuration

Cluster configuration Include in seed image
Performance profile Yes
MachineConfig resources for the target cluster Yes
IP version configuration, either IPv4, IPv6, or dual-stack networking Yes
Set of Day 2 Operators, including the Lifecycle Agent and the OADP Operator Yes
Disconnected registry configuration [2] Yes
Valid proxy configuration [3] Yes
FIPS configuration Yes
Dedicated partition on the primary disk for container storage that matches the size of the target clusters Yes
Local volumes

  • StorageClass used in LocalVolume for LSO
  • LocalVolume for LSO
  • LVMCluster CR for LVMS
 No
  1. If the seed cluster is installed in a disconnected environment, the target clusters must also be installed in a disconnected environment.
  2. The proxy configuration must be either enabled or disabled in both the seed and target clusters. However, the proxy servers configured on the clusters does not have to match.

Seed image configuration using the RAN DU profile​

The following table lists the components, resources, and configurations that you must and must not include in the seed image when using the RAN DU profile:

Seed image configuration with RAN DU profile

ResourceInclude in seed image
All extra manifests that are applied as part of Day 0 installationYes
All Day 2 Operator subscriptionsYes
DisableOLMPprof.yamlYes
TunedPerformancePatch.yamlYes
PerformanceProfile.yamlYes
SriovOperatorConfig.yamlYes
DisableSnoNetworkDiag.yamlYes
StorageClass.yamlNo, if it is used in StorageLV.yaml
StorageLV.yamlNo
StorageLVMCluster.yamlNo
SriovFecClusterConfig.yamlNo
SriovVrbClusterConfig.yamlNo

The following list of resources and configurations can be applied as extra manifests or by using RHACM policies:

  • ClusterLogForwarder.yaml
  • ReduceMonitoringFootprint.yaml
  • PtpOperatorConfigForEvent.yaml
  • DefaultCatsrc.yaml
  • PtpConfig.yaml
  • SriovNetwork.yaml
warning

If you are using GitOps ZTP, enable these resources by using RHACM policies to ensure configuration changes can be applied throughout the cluster lifecycle.

Generating a seed image with the Lifecycle Agent​

Use the Lifecycle Agent to generate a seed image from a managed cluster. The Operator checks for required system configurations, performs any necessary system cleanup before generating the seed image, and launches the image generation. The seed image generation includes the following tasks:

  • Stopping cluster Operators
  • Preparing the seed image configuration
  • Generating and pushing the seed image to the image repository specified in the SeedGenerator CR
  • Restoring cluster Operators
  • Expiring seed cluster certificates
  • Generating new certificates for the seed cluster
  • Restoring and updating the SeedGenerator CR on the seed cluster

Prerequisites

  • RHACM and multicluster engine for Kubernetes Operator are not installed on the seed cluster.
  • You have configured a shared container directory on the seed cluster.
  • You have installed the minimum version of the OADP Operator and the Lifecycle Agent on the seed cluster.
  • Ensure that persistent volumes are not configured on the seed cluster.
  • Ensure that the LocalVolume CR does not exist on the seed cluster if the Local Storage Operator is used.
  • Ensure that the LVMCluster CR does not exist on the seed cluster if LVM Storage is used.
  • Ensure that the DataProtectionApplication CR does not exist on the seed cluster if OADP is used.

Procedure

  1. Detach the managed cluster from the hub to delete any RHACM-specific resources from the seed cluster that must not be in the seed image:

    1. Manually detach the seed cluster by running the following command:

      $ oc delete managedcluster sno-worker-example
      1. Wait until the managed cluster is removed. After the cluster is removed, create the proper SeedGenerator CR. The Lifecycle Agent cleans up the RHACM artifacts.

    2. If you are using GitOps ZTP, detach your cluster by removing the seed cluster’s ClusterInstance CR from the kustomization.yaml.

      1. If you have a kustomization.yaml file that references multiple ClusterInstance CRs, remove your seed cluster’s ClusterInstance CR from the kustomization.yaml: 
        apiVersion: kustomize.config.k8s.io/v1beta1
        kind: Kustomization

        resources:
        #- clusterinstance-seed-sno1.yaml
        - clusterinstance-target-sno2.yaml
        - clusterinstance-target-sno3.yaml
      2. If you have a kustomization.yaml that references one ClusterInstance CR, remove your seed cluster’s ClusterInstance CR from the kustomization.yaml and add the resources: [] line: 
        apiVersion: kustomize.config.k8s.io/v1beta1
        kind: Kustomization

        resources: []
      3. Commit the kustomization.yaml changes in your Git repository and push the changes to your repository. The ArgoCD pipeline detects the changes and removes the managed cluster.

  2. Create the Secret object so that you can push the seed image to your registry.

    1. Create the authentication file by running the following commands:

      $ MY_USER=myuserid
      $ AUTHFILE=/tmp/my-auth.json
      $ podman login --authfile ${AUTHFILE} -u ${MY_USER} quay.io/${MY_USER}
      $ base64 -w 0 ${AUTHFILE} ; echo

    2. Copy the output into the seedAuth field in the Secret YAML file named seedgen in the openshift-lifecycle-agent namespace:

      apiVersion: v1
      kind: Secret
      metadata:
        name: <secret_name>
        namespace: openshift-lifecycle-agent
      type: Opaque
      data:
        seedAuth: <encoded_authfile>

      where:

      <secret_name>
      Specifies the name of the Secret resource. The value must be seedgen.
      <encoded_authfile>
      Specifies a base64-encoded authfile for write-access to the registry for pushing the generated seed images.

    3. Apply the Secret by running the following command:

      $ oc apply -f secretseedgenerator.yaml

  3. Create the SeedGenerator CR:

    apiVersion: lca.openshift.io/v1
    kind: SeedGenerator
    metadata:
      name: <seedgenerator_name>
    spec:
      seedImage: <seed_container_image>

    where:

    <seedgenerator_name>
    Specifies the name of the SeedGenerator CR. The value must be seedimage.
    <seed_container_image>
    Specifies the container image URL, for example, quay.io/example/seed-container-image:<tag>. It is recommended to use the <seed_cluster_name>:<ocp_version> format.

  4. Generate the seed image by running the following command:

    $ oc apply -f seedgenerator.yaml
    warning

    The cluster reboots and loses API capabilities while the Lifecycle Agent generates the seed image. Applying the SeedGenerator CR stops the kubelet and the CRI-O operations, then it starts the image generation.

Verification

  • After the cluster recovers and it is available, you can check the status of the SeedGenerator CR by running the following command:

    $ oc get seedgenerator -o yaml

    The following example shows the output when the seed image generation is complete:

    status:
      conditions:
      - lastTransitionTime: "2024-02-13T21:24:26Z"
        message: Seed Generation completed
        observedGeneration: 1
        reason: Completed
        status: "False"
        type: SeedGenInProgress
      - lastTransitionTime: "2024-02-13T21:24:26Z"
        message: Seed Generation completed
        observedGeneration: 1
        reason: Completed
        status: "True"
        type: SeedGenCompleted
      observedGeneration: 1

    The SeedGenCompleted type indicates that the seed image generation is complete.

    warning

    After the seed image generation completes, do not use the seed cluster. Do not continue to run oc commands against the seed cluster or use it to manage managed clusters.

    If you access the seed cluster after generating the seed image, you can meet TLS certificate validation errors because the seed cluster certificates expire during seed image generation. If you need to generate another seed image, provision a new seed cluster.