Creating a cluster with multi-architecture compute machines on IBM Power¶

To create a cluster with multi-architecture compute machines on IBM Power(R) (ppc64le), you must have an existing single-architecture (x86_64) cluster. You can then add ppc64le compute machines to your OpenShift Container Platform cluster.

Warning

Before you can add ppc64le nodes to your cluster, you must upgrade your cluster to one that uses the multi-architecture payload. For more information on migrating to the multi-architecture payload, see "Migrating to a cluster with multi-architecture compute machines".

The following procedures explain how to complete the following tasks:

Create a RHCOS compute machine by using an ISO image or network PXE booting.
Add ppc64le nodes to your cluster and deploy a cluster with multi-architecture compute machines.

To create an IBM Power(R) (ppc64le) cluster with multi-architecture compute machines on x86_64, follow the instructions for "Installing a cluster on IBM Power(R)". You can then add x86_64 compute machines as described in "Creating a cluster with multi-architecture compute machines on bare metal, IBM Power, or IBM Z".

Note

Before adding a secondary architecture node to your cluster, Red Hat recommends that you install the Multiarch Tuning Operator, and deploy a ClusterPodPlacementConfig object. For more information, see "Managing workloads on multi-architecture clusters by using the Multiarch Tuning Operator".

Additional resources

Create RHCOS machines by using an ISO image¶

To scale your OpenShift Container Platform cluster, you can create more Red Hat Enterprise Linux CoreOS (RHCOS) compute machines by using an ISO image.

Prerequisites

You have obtained the URL of the Ignition config file for the compute machines for your cluster. You uploaded this file to your HTTP server during installation.
You must have the OpenShift CLI (oc) installed.

Procedure

Extract the Ignition config file from the cluster by running the following command:

$ oc extract -n openshift-machine-api secret/worker-user-data-managed --keys=userData --to=- > worker.ign

Upload the worker.ign Ignition config file you exported from your cluster to your HTTP server. Note the URLs of these files.
You can validate that the ignition files are available on the URLs. The following example gets the Ignition config files for the compute node:
```
$ curl -k http://<HTTP_server>/worker.ign
```

You can access the ISO image for booting your new machine by running the following command:

RHCOS_VHD_ORIGIN_URL=$(oc -n openshift-machine-config-operator get configmap/coreos-bootimages -o jsonpath='{.data.stream}' | jq -r '.architectures.<architecture>.artifacts.metal.formats.iso.disk.location')

Use the ISO file to install RHCOS on more compute machines. Use the same method that you used when you created machines before you installed the cluster:
- Burn the ISO image to a disk and boot it directly.
- Use ISO redirection with a LOM interface.
Boot the RHCOS ISO image without specifying any options, or interrupting the live boot sequence. Wait for the installer to boot into a shell prompt in the RHCOS live environment.

Note

You can interrupt the RHCOS installation boot process to add kernel arguments. However, for this ISO procedure you must use the coreos-installer command as outlined in the following steps, instead of adding kernel arguments.
Run the coreos-installer command by using sudo. The core user does not have the root privileges required to perform the installation. Specify the options that meet your installation requirements. At a minimum, you must specify the URL that points to the Ignition config file for the node type, and the device that you are installing to.
```
$ sudo coreos-installer install --ignition-url=http://<HTTP_server>/<node_type>.ign <device> --ignition-hash=sha512-<digest>
```
where:

<digest>

Specifies the Ignition config file SHA512 digest obtained through an HTTP URL to validate the authenticity of the Ignition config file on the cluster node.

Note

If you want to provide your Ignition config files through an HTTPS server that uses TLS, you can add the internal certificate authority (CA) to the system trust store before running coreos-installer.

The following example initializes a compute node installation to the /dev/sda device. The Ignition config file for the compute node is obtained from an HTTP web server with the IP address 192.168.1.2:
```
$ sudo coreos-installer install --ignition-url=http://192.168.1.2:80/installation_directory/worker.ign /dev/sda --ignition-hash=sha512-a5a2d43879223273c9b60af66b44202a1d1248fc01cf156c46d4a79f552b6bad47bc8cc78ddf0116e80c59d2ea9e32ba53bc807afbca581aa059311def2c3e3b
```
Monitor the progress of the RHCOS installation on the console of the machine.

Warning

Ensure that the installation is successful on each node before commencing with the OpenShift Container Platform installation. Observing the installation process can also help to determine the cause of RHCOS installation issues that might arise.
Continue to create more compute machines for your cluster.

Create RHCOS machines by PXE or iPXE booting¶

To scale your OpenShift Container Platform bare metal cluster, you can create more Red Hat Enterprise Linux CoreOS (RHCOS) compute machines by using PXE or iPXE booting.

Prerequisites

You have obtained the URL of the Ignition config file for the compute machines for your cluster. You uploaded this file to your HTTP server during installation.
You have obtained the URLs of the RHCOS ISO image, compressed metal BIOS, kernel, and initramfs files that you uploaded to your HTTP server during cluster installation.
You have access to the PXE booting infrastructure that you used to create the machines for your OpenShift Container Platform cluster during installation. The machines must boot from their local disks after RHCOS is installed on them.
If you use UEFI, you have access to the grub.conf file that you modified during OpenShift Container Platform installation.

Procedure

Confirm that your PXE or iPXE installation for the RHCOS images is correct.
- For PXE:
```
DEFAULT pxeboot
TIMEOUT 20
PROMPT 0
LABEL pxeboot
    KERNEL http://<HTTP_server>/rhcos-<version>-live-kernel-<architecture>
    APPEND initrd=http://<HTTP_server>/rhcos-<version>-live-initramfs.<architecture>.img coreos.inst.install_dev=/dev/sda coreos.inst.ignition_url=http://<HTTP_server>/worker.ign coreos.live.rootfs_url=http://<HTTP_server>/rhcos-<version>-live-rootfs.<architecture>.img
```
  where:
  
  KERNEL
  
  Specifies the location of the live kernel file that you uploaded to your HTTP server.
  
  APPEND
  
  Specifies the locations of the RHCOS files that you uploaded to your HTTP server:
  
  initrd
  
  Specifies the location of the live initramfs file.
  
  coreos.inst.ignition_url
  
  Specifies the location of the worker Ignition config file. This parameter supports only HTTP and HTTPS.
  
  coreos.live.rootfs_url
  
  Specifies the location of the live rootfs file. This parameter supports only HTTP and HTTPS.
  
  Note
  
  This configuration does not enable serial console access on machines with a graphical console. To configure a different console, add one or more console= arguments to the APPEND line. For example, add console=tty0 console=ttyS0 to set the first PC serial port as the primary console and the graphical console as a secondary console. For more information on setting up a serial terminal and/or console in RHCOS, see "How does one set up a serial terminal and/or console in Red Hat Enterprise Linux?".
- For iPXE (x86_64 + ppc64le):
```
kernel http://<HTTP_server>/rhcos-<version>-live-kernel-<architecture> initrd=main coreos.live.rootfs_url=http://<HTTP_server>/rhcos-<version>-live-rootfs.<architecture>.img coreos.inst.install_dev=/dev/sda coreos.inst.ignition_url=http://<HTTP_server>/worker.ign
initrd --name main http://<HTTP_server>/rhcos-<version>-live-initramfs.<architecture>.img
boot
```
  where:
  
  kernel
  
  Specifies the location of the kernel file that you uploaded to your HTTP server.
  
  initrd=main
  
  Specifies an argument that is required for booting on UEFI systems.
  
  coreos.live.rootfs_url
  
  Specifies the location of the rootfs file that you uploaded to your HTTP server.
  
  coreos.inst.ignition_url
  
  Specifies the location of the worker Ignition config file that you uploaded to your HTTP server.
  
  initrd --name main
  
  Specifies the location of the initramfs file that you uploaded to your HTTP server.
  Note
  - If you use multiple NICs, specify a single interface in the ip option. For example, to use DHCP on a NIC named eno1, set ip=eno1:dhcp.
  - This configuration does not enable serial console access on machines with a graphical console. To configure a different console, add one or more console= arguments to the kernel line. For example, add console=tty0 console=ttyS0 to set the first PC serial port as the primary console and the graphical console as a secondary console. For more information on setting up a serial terminal and/or console in RHCOS, see "How does one set up a serial terminal and/or console in Red Hat Enterprise Linux?" in the Additional resources section and "Enabling the serial console for PXE and ISO installation" in the "Advanced RHCOS installation configuration" section.
  Note
  
  To network boot the CoreOS kernel on ppc64le architecture, you need to use a version of iPXE build with the IMAGE_GZIP option enabled. For more information, see "IMAGE_GZIP option in iPXE".
- For PXE (with UEFI and GRUB as second stage) on ppc64le:
```
menuentry 'Install CoreOS' {
    linux rhcos-<version>-live-kernel-<architecture>  coreos.live.rootfs_url=http://<HTTP_server>/rhcos-<version>-live-rootfs.<architecture>.img coreos.inst.install_dev=/dev/sda coreos.inst.ignition_url=http://<HTTP_server>/worker.ign
    initrd rhcos-<version>-live-initramfs.<architecture>.img
}
```
  where:
  
  linux
  
  Specifies the location of the live kernel file on your TFTP server.
  
  coreos.live.rootfs_url
  
  Specifies the location of the live rootfs file.
  
  coreos.inst.ignition_url
  
  Specifies the location of the worker Ignition config file.
  
  initrd
  
  Specifies the location of the live initramfs file on your TFTP server.
  
  Note
  
  If you use multiple NICs, specify a single interface in the ip option. For example, to use DHCP on a NIC named eno1, set ip=eno1:dhcp.
Use the PXE or iPXE infrastructure to create the required compute machines for your cluster.

Approve the certificate signing requests for your machines¶

To allow newly added machines to join your OpenShift Container Platform cluster, confirm that the cluster approves pending certificate signing requests (CSRs), or approve them yourself. Approve client requests first, then server requests.

Prerequisites

You added machines to your cluster.

Procedure

Confirm that the cluster recognizes the machines:
```
$ oc get nodes
```
Example output
```
NAME      STATUS    ROLES   AGE  VERSION
master-0  Ready     master  63m  v1.35.4
master-1  Ready     master  63m  v1.35.4
master-2  Ready     master  64m  v1.35.4
```
The output lists all of the machines that you created.

Note

The preceding output might not include the compute nodes until you approve some CSRs.

Review the pending CSRs and ensure that you see the client requests with the Pending or Approved status for each machine that you added to the cluster:

$ oc get csr

Example output

NAME        AGE     REQUESTOR                                                                   CONDITION
csr-8b2br   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending
csr-8vnps   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending
...

In this example, two machines are joining the cluster. You might see more approved CSRs in the list.

If the CSRs were not approved, after all of the pending CSRs for the machines you added are in Pending status, approve the CSRs for your cluster machines:

Note

You must approve your CSRs within an hour of adding the machines to the cluster. If you do not approve them within an hour, the certificates rotate, and more than two certificates are present for each node. You must approve all of these certificates. After you approve the client CSR, the kubelet creates a secondary CSR for the serving certificate, which requires manual approval. The machine-approver then automatically approves later serving certificate renewal requests if the kubelet requests a new certificate with the same parameters.

Note

For clusters running on platforms that are not machine API enabled, such as bare metal and other user-provisioned infrastructure, you must implement a method of automatically approving the kubelet serving certificate requests (CSRs). If you do not approve a request, the oc exec, oc rsh, and oc logs commands cannot succeed, because the API server requires a serving certificate when it connects to the kubelet. Any operation that contacts the kubelet endpoint requires this certificate approval to be in place. The method must watch for new CSRs, confirm that the node-bootstrapper service account in the system:node or system:admin groups submitted the CSR, and confirm the identity of the node.
- To approve them individually, run the following command for each valid CSR:
```
$ oc adm certificate approve <csr_name>
```
  where:
  
  <csr_name>
  
  Specifies the name of a CSR from the list of current CSRs.
- To approve all pending CSRs, run the following command:
```
$ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs --no-run-if-empty oc adm certificate approve
```
  Note
  
  Some Operators might not become available until you approve some CSRs. Each node submits two CSRs, so you might need to run the command to approve CSRs many times.

After you approve your client requests, review the server requests for each machine that you added to the cluster:

$ oc get csr

Example output

NAME        AGE     REQUESTOR                                                                   CONDITION
csr-bfd72   5m26s   system:node:ip-10-0-50-126.us-east-2.compute.internal                       Pending
csr-c57lv   5m26s   system:node:ip-10-0-95-157.us-east-2.compute.internal                       Pending
...

If the remaining CSRs are not approved, and are in the Pending status, approve the CSRs for your cluster machines:
- To approve them individually, run the following command for each valid CSR:
```
$ oc adm certificate approve <csr_name>
```
  where:
  
  <csr_name>
  
  Specifies the name of a CSR from the list of current CSRs.
- To approve all pending CSRs, run the following command:
```
$ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs oc adm certificate approve
```

After you approve all client and server CSRs, the machines have the Ready status. Verify this by running the following command:

$ oc get nodes -o wide

Example output

NAME               STATUS   ROLES                  AGE   VERSION   INTERNAL-IP      EXTERNAL-IP   OS-IMAGE                                                       KERNEL-VERSION                  CONTAINER-RUNTIME
worker-0-ppc64le   Ready    worker                 42d   v1.35.4   192.168.200.21   <none>        Red Hat Enterprise Linux CoreOS 415.92.202309261919-0 (Plow)   5.14.0-284.34.1.el9_2.ppc64le   cri-o://1.35.4-3.rhaos4.15.gitb36169e.el9
worker-1-ppc64le   Ready    worker                 42d   v1.35.4   192.168.200.20   <none>        Red Hat Enterprise Linux CoreOS 415.92.202309261919-0 (Plow)   5.14.0-284.34.1.el9_2.ppc64le   cri-o://1.35.4-3.rhaos4.15.gitb36169e.el9
master-0-x86       Ready    control-plane,master   75d   v1.35.4   10.248.0.38      10.248.0.38   Red Hat Enterprise Linux CoreOS 415.92.202309261919-0 (Plow)   5.14.0-284.34.1.el9_2.x86_64    cri-o://1.35.4-3.rhaos4.15.gitb36169e.el9
master-1-x86       Ready    control-plane,master   75d   v1.35.4   10.248.0.39      10.248.0.39   Red Hat Enterprise Linux CoreOS 415.92.202309261919-0 (Plow)   5.14.0-284.34.1.el9_2.x86_64    cri-o://1.35.4-3.rhaos4.15.gitb36169e.el9
master-2-x86       Ready    control-plane,master   75d   v1.35.4   10.248.0.40      10.248.0.40   Red Hat Enterprise Linux CoreOS 415.92.202309261919-0 (Plow)   5.14.0-284.34.1.el9_2.x86_64    cri-o://1.35.4-3.rhaos4.15.gitb36169e.el9
worker-0-x86       Ready    worker                 75d   v1.35.4   10.248.0.43      10.248.0.43   Red Hat Enterprise Linux CoreOS 415.92.202309261919-0 (Plow)   5.14.0-284.34.1.el9_2.x86_64    cri-o://1.35.4-3.rhaos4.15.gitb36169e.el9
worker-1-x86       Ready    worker                 75d   v1.35.4   10.248.0.44      10.248.0.44   Red Hat Enterprise Linux CoreOS 415.92.202309261919-0 (Plow)   5.14.0-284.34.1.el9_2.x86_64    cri-o://1.35.4-3.rhaos4.15.gitb36169e.el9

Note

You might need to wait a few minutes after approval of the server CSRs for the machines to reach the Ready status.