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About image-based installations for single-node OpenShift clusters

Use the openshift-install installation program to create a live installation ISO for preinstalling single-node OpenShift on bare-metal hosts. For more information about downloading the installation program, see "Installation process" in the "Additional resources" section.

The installation program takes a seed image URL and other inputs, such as the release version of the seed image and the disk to use for the installation process, and creates a live installation ISO. You can then start the host using the live installation ISO to begin preinstallation. When preinstallation is complete, the host is ready to ship to a remote site for the final site-specific configuration and deployment.

The following are the high-level steps to preinstall a single-node OpenShift cluster using an image-based installation:

  • Generate a seed image.

  • Create a live installation ISO using the installation program.

  • Start the host using the live installation ISO to preinstall the host.

Additional resources

Creating a live installation ISO for a single-node OpenShift image-based installation

You can embed your single-node OpenShift seed image URL, and other installation artifacts, in a live installation ISO by using the openshift-install installation program.

For more information about the specification for the image-based-installation-config.yaml manifest, see the section Reference specifications for the image-based-installation-config.yaml manifest.
Prerequisites

  • You generated a seed image from a single-node OpenShift seed cluster.

  • You downloaded the latest version of the openshift-install installation program.

  • The target host has network access to the seed image URL and all other installation artifacts.

  • If you require static networking, you must install the nmstatectl library on the host that creates the live installation ISO.

Procedure

  1. Create a live installation ISO and embed your single-node OpenShift seed image URL and other installation artifacts:

    1. Create a working directory by running the following:

      $ mkdir ibi-iso-workdir (1)
      1 Replace ibi-iso-workdir with the name of your working directory.

    2. Optional. Create an installation configuration template to use as a reference when configuring the ImageBasedInstallationConfig resource:

      $ openshift-install image-based create image-config-template --dir ibi-iso-workdir (1)
      1 If you do not specify a working directory, the command uses the current directory.
      Example output
      INFO Image-Config-Template created in: ibi-iso-workdir

      The command creates the image-based-installation-config.yaml installation configuration template in your target directory:

      #
# Note: This is a sample ImageBasedInstallationConfig file showing
# which fields are available to aid you in creating your
# own image-based-installation-config.yaml file.
#
apiVersion: v1beta1
kind: ImageBasedInstallationConfig
metadata:
  name: example-image-based-installation-config
# The following fields are required
seedImage: quay.io/openshift-kni/seed-image:4.17.0
seedVersion: 4.17.0
installationDisk: /dev/vda
pullSecret: '<your_pull_secret>'
# networkConfig is optional and contains the network configuration for the host in NMState format.
# See https://nmstate.io/examples.html for examples.
# networkConfig:
#   interfaces:
#     - name: eth0
#       type: ethernet
#       state: up
#       mac-address: 00:00:00:00:00:00
#       ipv4:
#         enabled: true
#         address:
#           - ip: 192.168.122.2
#             prefix-length: 23
#         dhcp: false

    3. Edit your installation configuration file:

      Example image-based-installation-config.yaml file
      apiVersion: v1beta1
kind: ImageBasedInstallationConfig
metadata:
  name: example-image-based-installation-config
seedImage: quay.io/repo-id/seed:latest
seedVersion: "4.17.0"
extraPartitionStart: "-240G"
installationDisk: /dev/disk/by-id/wwn-0x62c...
sshKey: 'ssh-ed25519 AAAA...'
pullSecret: '{"auths": ...}'
networkConfig:
    interfaces:
      - name: ens1f0
        type: ethernet
        state: up
        ipv4:
          enabled: true
          dhcp: false
          auto-dns: false
          address:
            - ip: 10.6.85.8
              prefix-length: 24
        ipv6:
          enabled: false
    dns-resolver:
      config:
        server:
          - 10.6.73.2
          - 10.6.73.4
    routes:
      config:
      - destination: 0.0.0.0/0
        metric: 150
        next-hop-address: 10.6.85.254
        next-hop-interface: ens1f0

    4. Create the live installation ISO by running the following command:

      $ openshift-install image-based create image --dir ibi-iso-workdir
      Example output
      INFO Consuming Image-based Installation ISO Config from target directory
INFO Creating Image-based Installation ISO with embedded ignition
Verification

  • View the output in the working directory:

    ibi-iso-workdir/
  └── rhcos-ibi.iso

Provisioning the live installation ISO to a host

Using your preferred method, boot the target bare-metal host from the rhcos-ibi.iso live installation ISO to preinstall single-node OpenShift.

Verification

  1. Login to the target host.

  2. View the system logs by running the following command:

    $ journalctl -b
    Example output
    Aug 13 17:01:44 10.46.26.129 install-rhcos-and-restore-seed.sh[2876]: time="2024-08-13T17:01:44Z" level=info msg="All the precaching threads have finished."
Aug 13 17:01:44 10.46.26.129 install-rhcos-and-restore-seed.sh[2876]: time="2024-08-13T17:01:44Z" level=info msg="Total Images: 125"
Aug 13 17:01:44 10.46.26.129 install-rhcos-and-restore-seed.sh[2876]: time="2024-08-13T17:01:44Z" level=info msg="Images Pulled Successfully: 125"
Aug 13 17:01:44 10.46.26.129 install-rhcos-and-restore-seed.sh[2876]: time="2024-08-13T17:01:44Z" level=info msg="Images Failed to Pull: 0"
Aug 13 17:01:44 10.46.26.129 install-rhcos-and-restore-seed.sh[2876]: time="2024-08-13T17:01:44Z" level=info msg="Completed executing pre-caching"
Aug 13 17:01:44 10.46.26.129 install-rhcos-and-restore-seed.sh[2876]: time="2024-08-13T17:01:44Z" level=info msg="Pre-cached images successfully."
Aug 13 17:01:44 10.46.26.129 install-rhcos-and-restore-seed.sh[2876]: time="2024-08-13 17:01:44" level=info msg="Skipping shutdown"
Aug 13 17:01:44 10.46.26.129 install-rhcos-and-restore-seed.sh[2876]: time="2024-08-13 17:01:44" level=info msg="IBI preparation process finished successfully!"
Aug 13 17:01:44 10.46.26.129 systemd[1]: var-lib-containers-storage-overlay.mount: Deactivated successfully.
Aug 13 17:01:44 10.46.26.129 systemd[1]: Finished SNO Image-based Installation.
Aug 13 17:01:44 10.46.26.129 systemd[1]: Reached target Multi-User System.
Aug 13 17:01:44 10.46.26.129 systemd[1]: Reached target Graphical Interface.

Reference specifications for the image-based-installation-config.yaml manifest

The following content describes the specifications for the image-based-installation-config.yaml manifest.

The OpenShift Container Platform installation program uses the `image-based-installation-config.yaml manifest to create a live installation ISO for image-based installations of single-node OpenShift.

Table 1. Required specifications
Specification Type Description

seedImage

string

Specifies the seed image to use in the ISO generation process.

seedVersion

string

Specifies the OpenShift Container Platform release version of the seed image. The release version in the seed image must match the release version that you specify in the seedVersion field.

installationDisk

string

Specifies the disk that will be used for the installation process.

Because the disk discovery order is not guaranteed, the kernel name of the disk can change across booting options for machines with multiple disks. For example, /dev/sda becomes /dev/sdb and vice versa. To avoid this issue, you must use a persistent disk attribute, such as the disk World Wide Name (WWN), for example: /dev/disk/by-id/wwn-<disk-id>.

pullSecret

string

Specifies the pull secret to use during the precache process. The pull secret contains authentication credentials for pulling the release payload images from the container registry.

If the seed image requires a separate private registry authentication, add the authentication details to the pull secret.
Table 2. Optional specifications
Specification Type Description

shutdown

boolean

Specifies if the host shuts down after the installation process completes. The default value is false.

extraPartitionStart

string

Specifies the start of the extra partition used for /var/lib/containers. The default value is -40Gb, which means that the partition will be exactly 40Gb in size and uses the space 40Gb from the end of the disk. If you specify a positive value, the partition will start at that position of the disk and extend to the end of the disk.

extraPartitionLabel

string

The label of the extra partition you use for /var/lib/containers. The default label is varlibcontainers.

extraPartitionNumber

unsigned integer

The number of the extra partition you use for /var/lib/containers. The default number is 5.

skipDiskCleanup

boolean

The installation process formats the disk on the host. Set this specification to 'true' to skip this step. The default is false.

networkConfig

string

Specifies networking configurations for the host, for example:

networkConfig:
    interfaces:
      - name: ens1f0
        type: ethernet
        state: up
        ...

If you require static networking, you must install the nmstatectl library on the host that creates the live installation ISO. For further information about defining network configurations by using nmstate, see nmstate.io.

The name of the interface must match the actual NIC name as shown in the operating system.

proxy

string

Specifies proxy settings to use during the installation ISO generation, for example:

proxy:
  httpProxy: "http://proxy.example.com:8080"
  httpsProxy: "http://proxy.example.com:8080"
  noProxy: "no_proxy.example.com"

imageDigestSources

string

Specifies the sources or repositories for the release-image content, for example:

imageDigestSources:
  - mirrors:
      - "registry.example.com:5000/ocp4/openshift4"
    source: "quay.io/openshift-release-dev/ocp-release"

additionalTrustBundle

string

Specifies the PEM-encoded X.509 certificate bundle. The installation program adds this to the /etc/pki/ca-trust/source/anchors/ directory in the installation ISO.

additionalTrustBundle: |
  -----BEGIN CERTIFICATE-----
  MTICLDCCAdKgAwfBAgIBAGAKBggqhkjOPQRDAjB9MQswCQYRVEQGE
  ...
  l2wOuDwKQa+upc4GftXE7C//4mKBNBC6Ty01gUaTIpo=
  -----END CERTIFICATE-----

sshKey

string

Specifies the SSH key to authenticate access to the host.

ignitionConfigOverride

string

Specifies a JSON string containing the user overrides for the Ignition config. The configuration merges with the Ignition config file generated by the installation program. This feature requires Ignition version is 3.2 or later.