Preparing PXE assets for OCP - Installing an on-premise cluster with the Agent-based Installer | Installing

Prerequisites
Downloading the Agent-based Installer
Creating the preferred configuration inputs
Creating the PXE assets

Use the following procedures to create the assets needed to PXE boot an OpenShift Container Platform cluster using the Agent-based Installer.

The assets you create in these procedures will deploy a single-node OpenShift Container Platform installation. You can use these procedures as a basis and modify configurations according to your requirements.

See Installing an OpenShift Container Platform cluster with the Agent-based Installer to learn about more configurations available with the Agent-based Installer.

Prerequisites

You reviewed details about the OpenShift Container Platform installation and update processes.

Downloading the Agent-based Installer

Use this procedure to download the Agent-based Installer and the CLI needed for your installation.

Procedure

Log in to the OpenShift Container Platform web console using your login credentials.
Navigate to Datacenter.
Click Run Agent-based Installer locally.
Select the operating system and architecture for the OpenShift Installer and Command line interface.
Click Download Installer to download and extract the install program.
Download or copy the pull secret by clicking on Download pull secret or Copy pull secret.
Click Download command-line tools and place the openshift-install binary in a directory that is on your PATH.

Creating the preferred configuration inputs

Use this procedure to create the preferred configuration inputs used to create the PXE files.

Procedure

Install nmstate dependency by running the following command:
```
$ sudo dnf install /usr/bin/nmstatectl -y
```
Place the openshift-install binary in a directory that is on your PATH.
Create a directory to store the install configuration by running the following command:
```
$ mkdir ~/<directory_name>
```
This is the preferred method for the Agent-based installation. Using GitOps ZTP manifests is optional.

Create the install-config.yaml file by running the following command:

$ cat << EOF > ./my-cluster/install-config.yaml
apiVersion: v1
baseDomain: test.example.com
compute:
- architecture: amd64 (1)
  hyperthreading: Enabled
  name: worker
  replicas: 0
controlPlane:
  architecture: amd64
  hyperthreading: Enabled
  name: master
  replicas: 1
metadata:
  name: sno-cluster (2)
networking:
  clusterNetwork:
  - cidr: 10.128.0.0/14
    hostPrefix: 23
  machineNetwork:
  - cidr: 192.168.0.0/16
  networkType: OVNKubernetes (3)
  serviceNetwork:
  - 172.30.0.0/16
platform:
  none: {}
pullSecret: '<pull_secret>' (4)
sshKey: '<ssh_pub_key>' (5)
EOF

1	Specify the system architecture, valid values are `amd64` and `arm64`.
2	Required. Specify your cluster name.
3	Specify the cluster network plugin to install. The supported values are `OVNKubernetes` and `OpenShiftSDN`. The default value is `OVNKubernetes`.
4	Specify your pull secret.
5	Specify your SSH public key.

If you set the platform to vSphere or baremetal, you can configure IP address endpoints for cluster nodes in three ways:

IPv4
IPv6
IPv4 and IPv6 in parallel (dual-stack)

IPv6 is supported only on bare metal platforms.

Example of dual-stack networking

networking:
  clusterNetwork:
    - cidr: 172.21.0.0/16
      hostPrefix: 23
    - cidr: fd02::/48
      hostPrefix: 64
  machineNetwork:
    - cidr: 192.168.11.0/16
    - cidr: 2001:DB8::/32
  serviceNetwork:
    - 172.22.0.0/16
    - fd03::/112
  networkType: OVNKubernetes
platform:
  baremetal:
    apiVIPs:
    - 192.168.11.3
    - 2001:DB8::4
    ingressVIPs:
    - 192.168.11.4
    - 2001:DB8::5

When you use a disconnected mirror registry, you must add the certificate file that you created previously for your mirror registry to the additionalTrustBundle field of the install-config.yaml file.

Create the agent-config.yaml file by running the following command:

$ cat > agent-config.yaml << EOF
apiVersion: v1beta1
kind: AgentConfig
metadata:
  name: sno-cluster
rendezvousIP: 192.168.111.80 (1)
hosts: (2)
  - hostname: master-0 (3)
    interfaces:
      - name: eno1
        macAddress: 00:ef:44:21:e6:a5
    rootDeviceHints: (4)
      deviceName: /dev/sdb
    networkConfig: (5)
      interfaces:
        - name: eno1
          type: ethernet
          state: up
          mac-address: 00:ef:44:21:e6:a5
          ipv4:
            enabled: true
            address:
              - ip: 192.168.111.80
                prefix-length: 23
            dhcp: false
      dns-resolver:
        config:
          server:
            - 192.168.111.1
      routes:
        config:
          - destination: 0.0.0.0/0
            next-hop-address: 192.168.111.2
            next-hop-interface: eno1
            table-id: 254
EOF

1	This IP address is used to determine which node performs the bootstrapping process as well as running the `assisted-service` component. You must provide the rendezvous IP address when you do not specify at least one host’s IP address in the `networkConfig` parameter. If this address is not provided, one IP address is selected from the provided hosts' `networkConfig`.
2	Optional: Host configuration. The number of hosts defined must not exceed the total number of hosts defined in the `install-config.yaml` file, which is the sum of the values of the `compute.replicas` and `controlPlane.replicas` parameters.
3	Optional: Overrides the hostname obtained from either the Dynamic Host Configuration Protocol (DHCP) or a reverse DNS lookup. Each host must have a unique hostname supplied by one of these methods.
4	Enables provisioning of the Red Hat Enterprise Linux CoreOS (RHCOS) image to a particular device. The installation program examines the devices in the order it discovers them, and compares the discovered values with the hint values. It uses the first discovered device that matches the hint value.
5	Optional: Configures the network interface of a host in NMState format.

Optional: To create an iPXE script, add the bootArtifactsBaseURL to the agent-config.yaml file:
```
apiVersion: v1beta1
kind: AgentConfig
metadata:
  name: sno-cluster
rendezvousIP: 192.168.111.80
bootArtifactsBaseURL: <asset_server_URL>
```
Where <asset_server_URL> is the URL of the server you will upload the PXE assets to.

Additional resources

Deploying with dual-stack networking.
Configuring the install-config yaml file.
See Configuring a three-node cluster to deploy three-node clusters in bare metal environments.
About root device hints.
NMState state examples.
Optional: Creating additional manifest files

Creating the PXE assets

Use the following procedure to create the assets and optional script to implement in your PXE infrastructure.

Procedure

Create the PXE assets by running the following command:

$ openshift-install agent create pxe-files

The generated PXE assets and optional iPXE script can be found in the boot-artifacts directory.

Example filesystem with PXE assets and optional iPXE script

boot-artifacts
    ├─ agent.x86_64-initrd.img
    ├─ agent.x86_64.ipxe
    ├─ agent.x86_64-rootfs.img
    └─ agent.x86_64-vmlinuz

Red Hat Enterprise Linux CoreOS (RHCOS) supports multipathing on the primary disk, allowing stronger resilience to hardware failure to achieve higher host availability. Multipathing is enabled by default in the agent ISO image, with a default /etc/multipath.conf configuration.

Upload the PXE assets and optional script to your infrastructure where they will be accessible during the boot process.

If you generated an iPXE script, the location of the assets must match the bootArtifactsBaseURL you added to the agent-config.yaml file.

Preparing PXE assets for OpenShift Container Platform

Prerequisites

Downloading the Agent-based Installer

Creating the preferred configuration inputs

Creating the PXE assets