Preparing for image-based installation for {sno} 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

Software prerequisites for an image-based installation and deployment

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

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

Create the Namespace CR by running the following command:
```
$ oc create -f <namespace_filename>.yaml
```

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

Create the OperatorGroup CR by running the following command:
```
$ oc create -f <operatorgroup_filename>.yaml
```

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

Create the Subscription CR by running the following command:
```
$ oc create -f <subscription_filename>.yaml
```

Verification

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.v4.19.0           Openshift Lifecycle Agent   4.19.0                Succeeded

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

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

Verification

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:

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

Configuring a shared container partition between ostree stateroots

Important

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/pci-<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

Specify the root disk.
Specify the start of the partition in MiB. If the value is too small, the installation will fail.
Specify a minimum size for the partition of 500 GB 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:

Table 1. 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

If the seed cluster is installed in a disconnected environment, the target clusters must also be installed in a disconnected environment.
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:

Table 2. Seed image configuration with RAN DU profile
Resource	Include in seed image
All extra manifests that are applied as part of Day 0 installation	Yes
All Day 2 Operator subscriptions	Yes
`DisableOLMPprof.yaml`	Yes
`TunedPerformancePatch.yaml`	Yes
`PerformanceProfile.yaml`	Yes
`SriovOperatorConfig.yaml`	Yes
`DisableSnoNetworkDiag.yaml`	Yes
`StorageClass.yaml`	No, if it is used in `StorageLV.yaml`
`StorageLV.yaml`	No
`StorageLVMCluster.yaml`	No

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

ClusterLogForwarder.yaml
ReduceMonitoringFootprint.yaml
SriovFecClusterConfig.yaml
PtpOperatorConfigForEvent.yaml
DefaultCatsrc.yaml
PtpConfig.yaml
SriovNetwork.yaml

Important

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

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.
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: seedgen namespace: openshift-lifecycle-agent type: Opaque data: seedAuth: <encoded_AUTHFILE>
  1. The Secret resource must have the name: seedgen and namespace: openshift-lifecycle-agent fields.
  2. 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
Create the SeedGenerator CR:
```
apiVersion: lca.openshift.io/v1
kind: SeedGenerator
metadata:
  name: seedimage 
spec:
  seedImage: <seed_container_image> 
```
1. The SeedGenerator CR must be named seedimage.
2. Specify 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.
Generate the seed image by running the following command:
```
$ oc apply -f seedgenerator.yaml
```
Important

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.

If you want to generate more seed images, you must provision a new seed cluster with the version that you want to generate a seed image from.

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
```

Example output

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 seed image generation is complete.