Chapter 2. Installing OpenShift on a single node

Procedure

1. On the administration host, open a browser and navigate to Red Hat OpenShift Cluster Manager.
2. Click Create Cluster to create a new cluster.
3. In the Cluster name field, enter a name for the cluster.

4. In the Base domain field, enter a base domain. For example:

   example.com

   All DNS records must be subdomains of this base domain and include the cluster name, for example:

   <cluster-name>.example.com

   Note

   You cannot change the base domain or cluster name after cluster installation.

5. Select Install single node OpenShift (SNO) and complete the rest of the wizard steps. Download the discovery ISO.
6. Make a note of the discovery ISO URL for installing with virtual media.

Procedure

1. Attach the RHCOS discovery ISO to the target host.
2. Configure the boot drive order in the server BIOS settings to boot from the attached discovery ISO and then reboot the server.
3. On the administration host, return to the browser. Wait for the host to appear in the list of discovered hosts. If necessary, reload the Assisted Clusters page and select the cluster name.
4. Complete the install wizard steps. Add networking details, including a subnet from the available subnets. Add the SSH public key if necessary.
5. Monitor the installation’s progress. Watch the cluster events. After the installation process finishes writing the operating system image to the server’s hard disk, the server restarts.

6. Remove the discovery ISO, and reset the server to boot from the installation drive.

   The server restarts several times automatically, deploying the control plane.

Procedure

1. Set the OpenShift Container Platform version:

   $ OCP_VERSION=<ocp_version> 1

   1

   Replace <ocp_version> with the current version, for example, latest-4.12

2. Set the host architecture:

   $ ARCH=<architecture> 1

   1

   Replace <architecture> with the target host architecture, for example, aarch64 or x86_64.

3. Download the OpenShift Container Platform client (oc) and make it available for use by entering the following commands:

   $ curl -k https://mirror.openshift.com/pub/openshift-v4/clients/ocp/$OCP_VERSION/openshift-client-linux.tar.gz -o oc.tar.gz

   $ tar zxf oc.tar.gz

   $ chmod +x oc

4. Download the OpenShift Container Platform installer and make it available for use by entering the following commands:

   $ curl -k https://mirror.openshift.com/pub/openshift-v4/clients/ocp/$OCP_VERSION/openshift-install-linux.tar.gz -o openshift-install-linux.tar.gz

   $ tar zxvf openshift-install-linux.tar.gz

   $ chmod +x openshift-install

5. Retrieve the RHCOS ISO URL by running the following command:

   $ ISO_URL=$(./openshift-install coreos print-stream-json | grep location | grep $ARCH | grep iso | cut -d\" -f4)

6. Download the RHCOS ISO:

   $ curl -L $ISO_URL -o rhcos-live.iso

7. Prepare the install-config.yaml file:

   apiVersion: v1
   baseDomain: <domain> 1
   compute:
   - architecture: amd64 2
     name: worker
     replicas: 0 3
   controlPlane:
     architecture: amd64
     name: master
     replicas: 1 4
   metadata:
     name: <name> 5
   networking: 6
     clusterNetwork:
     - cidr: 10.128.0.0/14
       hostPrefix: 23
     machineNetwork:
     - cidr: 10.0.0.0/16 7
     networkType: OVNKubernetes
     serviceNetwork:
     - 172.30.0.0/16
   platform:
     none: {}
   bootstrapInPlace:
     installationDisk: /dev/disk/by-id/<disk_id> 8
   pullSecret: '<pull_secret>' 9
   sshKey: |
     <ssh_key> 10

   1

   Add the cluster domain name.

   2

   Set the architecture to arm64 for 64-bit ARM or amd64 for 64-bit x86 architectures. This needs to be set explicitly to the target host architecture.

   3

   Set the compute replicas to 0. This makes the control plane node schedulable.

   4

   Set the controlPlane replicas to 1. In conjunction with the previous compute setting, this setting ensures the cluster runs on a single node.

   5

   Set the metadata name to the cluster name.

   6

   Set the networking details. OVN-Kubernetes is the only allowed network plugin type for single-node clusters.

   7

   Set the cidr value to match the subnet of the single-node OpenShift cluster.

   8

   Set the path to the installation disk drive, for example, /dev/disk/by-id/wwn-0x64cd98f04fde100024684cf3034da5c2.

   9

   Copy the pull secret from the Red Hat OpenShift Cluster Manager and add the contents to this configuration setting.

   10

   Add the public SSH key from the administration host so that you can log in to the cluster after installation.

8. Generate OpenShift Container Platform assets by running the following commands:

   $ mkdir ocp

   $ cp install-config.yaml ocp

   $ ./openshift-install --dir=ocp create single-node-ignition-config

9. Embed the ignition data into the RHCOS ISO by running the following commands:

   $ alias coreos-installer='podman run --privileged --pull always --rm \
           -v /dev:/dev -v /run/udev:/run/udev -v $PWD:/data \
           -w /data quay.io/coreos/coreos-installer:release'

   $ coreos-installer iso ignition embed -fi ocp/bootstrap-in-place-for-live-iso.ign rhcos-live.iso

Procedure

1. Attach the modified RHCOS installation ISO to the target host.
2. Configure the boot drive order in the server BIOS settings to boot from the attached discovery ISO and then reboot the server.

3. On the administration host, monitor the installation by running the following command:

   $ ./openshift-install --dir=ocp wait-for install-complete

   The server restarts several times while deploying the control plane.