Chapter 4. Configuring multi-architecture compute machines on an OpenShift Container Platform cluster

Procedure

1. Log in to your Azure account:

   $ az login

2. Create a storage account and upload the arm64 virtual hard disk (VHD) to your storage account. The OpenShift Container Platform installation program creates a resource group, however, the boot image can also be uploaded to a custom named resource group:

   $ az storage account create -n ${STORAGE_ACCOUNT_NAME} -g ${RESOURCE_GROUP} -l westus --sku Standard_LRS 1

   1

   The westus object is an example region.

3. Create a storage container using the storage account you generated:

   $ az storage container create -n ${CONTAINER_NAME} --account-name ${STORAGE_ACCOUNT_NAME}

4. You must use the OpenShift Container Platform installation program JSON file to extract the URL and aarch64 VHD name:

   1. Extract the URL field and set it to RHCOS_VHD_ORIGIN_URL as the file name 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.aarch64."rhel-coreos-extensions"."azure-disk".url')

   2. Extract the aarch64 VHD name and set it to BLOB_NAME as the file name by running the following command:

      $ BLOB_NAME=rhcos-$(oc -n openshift-machine-config-operator get configmap/coreos-bootimages -o jsonpath='{.data.stream}' | jq -r '.architectures.aarch64."rhel-coreos-extensions"."azure-disk".release')-azure.aarch64.vhd

5. Generate a shared access signature (SAS) token. Use this token to upload the RHCOS VHD to your storage container with the following commands:

   $ end=`date -u -d "30 minutes" '+%Y-%m-%dT%H:%MZ'`

   $ sas=`az storage container generate-sas -n ${CONTAINER_NAME} --account-name ${STORAGE_ACCOUNT_NAME} --https-only --permissions dlrw --expiry $end -o tsv`

6. Copy the RHCOS VHD into the storage container:

   $ az storage blob copy start --account-name ${STORAGE_ACCOUNT_NAME} --sas-token "$sas" \
    --source-uri "${RHCOS_VHD_ORIGIN_URL}" \
    --destination-blob "${BLOB_NAME}" --destination-container ${CONTAINER_NAME}

   You can check the status of the copying process with the following command:

   $ az storage blob show -c ${CONTAINER_NAME} -n ${BLOB_NAME} --account-name ${STORAGE_ACCOUNT_NAME} | jq .properties.copy

   Example output

   {
    "completionTime": null,
    "destinationSnapshot": null,
    "id": "1fd97630-03ca-489a-8c4e-cfe839c9627d",
    "incrementalCopy": null,
    "progress": "17179869696/17179869696",
    "source": "https://rhcos.blob.core.windows.net/imagebucket/rhcos-411.86.202207130959-0-azure.aarch64.vhd",
    "status": "success", 1
    "statusDescription": null
   }

   1

   If the status parameter displays the success object, the copying process is complete.

7. Create an image gallery using the following command:

   $ az sig create --resource-group ${RESOURCE_GROUP} --gallery-name ${GALLERY_NAME}

   Use the image gallery to create an image definition. In the following example command, rhcos-arm64 is the name of the image definition.

   $ az sig image-definition create --resource-group ${RESOURCE_GROUP} --gallery-name ${GALLERY_NAME} --gallery-image-definition rhcos-arm64 --publisher RedHat --offer arm --sku arm64 --os-type linux --architecture Arm64 --hyper-v-generation V2

8. To get the URL of the VHD and set it to RHCOS_VHD_URL as the file name, run the following command:

   $ RHCOS_VHD_URL=$(az storage blob url --account-name ${STORAGE_ACCOUNT_NAME} -c ${CONTAINER_NAME} -n "${BLOB_NAME}" -o tsv)

9. Use the RHCOS_VHD_URL file, your storage account, resource group, and image gallery to create an image version. In the following example, 1.0.0 is the image version.

   $ az sig image-version create --resource-group ${RESOURCE_GROUP} --gallery-name ${GALLERY_NAME} --gallery-image-definition rhcos-arm64 --gallery-image-version 1.0.0 --os-vhd-storage-account ${STORAGE_ACCOUNT_NAME} --os-vhd-uri ${RHCOS_VHD_URL}

10. Your arm64 boot image is now generated. You can access the ID of your image with the following command:

    $ az sig image-version show -r $GALLERY_NAME -g $RESOURCE_GROUP -i rhcos-arm64 -e 1.0.0

    The following example image ID is used in the recourseID parameter of the compute machine set:

    Example resourceID

    /resourceGroups/${RESOURCE_GROUP}/providers/Microsoft.Compute/galleries/${GALLERY_NAME}/images/rhcos-arm64/versions/1.0.0

Verification

1. Verify that the new ARM64 machines are running by entering the following command:

   $ oc get machineset -n openshift-machine-api

   Example output

   NAME                                                DESIRED  CURRENT  READY  AVAILABLE  AGE
   <infrastructure_id>-arm64-machine-set-0                   2        2      2          2  10m

2. You can check that the nodes are ready and scheduable with the following command:

   $ oc get nodes

Verification

1. View the list of compute machine sets by entering the following command:

   $ oc get machineset -n openshift-machine-api

   You can then see your created ARM64 machine set.

   Example output

   NAME                                                DESIRED  CURRENT  READY  AVAILABLE  AGE
   <infrastructure_id>-aws-arm64-machine-set-0                   2        2      2          2  10m

2. You can check that the nodes are ready and scheduable with the following command:

   $ oc get nodes

Procedure

1. 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

2. Upload the worker.ign Ignition config file you exported from your cluster to your HTTP server. Note the URLs of these files.

3. 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

4. You can access the ISO image for booting your new machine by running to 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')

5. 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.

6. 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.

7. Run the coreos-installer command and 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> 12

   1

   You must run the coreos-installer command by using sudo, because the core user does not have the required root privileges to perform the installation.

   2

   The --ignition-hash option is required when the Ignition config file is obtained through an HTTP URL to validate the authenticity of the Ignition config file on the cluster node. <digest> is the Ignition config file SHA512 digest obtained in a preceding step.

   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 bootstrap node installation to the /dev/sda device. The Ignition config file for the bootstrap 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/bootstrap.ign /dev/sda --ignition-hash=sha512-a5a2d43879223273c9b60af66b44202a1d1248fc01cf156c46d4a79f552b6bad47bc8cc78ddf0116e80c59d2ea9e32ba53bc807afbca581aa059311def2c3e3b

8. Monitor the progress of the RHCOS installation on the console of the machine.

   Important

   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.

9. Continue to create more compute machines for your cluster.

Procedure

1. 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> 1
         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 2

     1

     Specify the location of the live kernel file that you uploaded to your HTTP server.

     2

     Specify locations of the RHCOS files that you uploaded to your HTTP server. The initrd parameter value is the location of the live initramfs file, the coreos.inst.ignition_url parameter value is the location of the worker Ignition config file, and the coreos.live.rootfs_url parameter value is the location of the live rootfs file. The coreos.inst.ignition_url and coreos.live.rootfs_url parameters only support 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, see How does one set up a serial terminal and/or console in Red Hat Enterprise Linux?.

   • For iPXE (x86_64 + aarch64):

     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 1 2
     initrd --name main http://<HTTP_server>/rhcos-<version>-live-initramfs.<architecture>.img 3
     boot

     1

     Specify the locations of the RHCOS files that you uploaded to your HTTP server. The kernel parameter value is the location of the kernel file, the initrd=main argument is needed for booting on UEFI systems, the coreos.live.rootfs_url parameter value is the location of the rootfs file, and the coreos.inst.ignition_url parameter value is the location of the worker Ignition config file.

     2

     If you use multiple NICs, specify a single interface in the ip option. For example, to use DHCP on a NIC that is named eno1, set ip=eno1:dhcp.

     3

     Specify the location of the initramfs file that you uploaded to your HTTP server.

     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 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, see How does one set up a serial terminal and/or console in Red Hat Enterprise Linux? 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 aarch64 architecture, you need to use a version of iPXE build with the IMAGE_GZIP option enabled. See IMAGE_GZIP option in iPXE.

   • For PXE (with UEFI and GRUB as second stage) on aarch64:

     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 1 2
         initrd rhcos-<version>-live-initramfs.<architecture>.img 3
     }

     1

     Specify the locations of the RHCOS files that you uploaded to your HTTP/TFTP server. The kernel parameter value is the location of the kernel file on your TFTP server. The coreos.live.rootfs_url parameter value is the location of the rootfs file, and the coreos.inst.ignition_url parameter value is the location of the worker Ignition config file on your HTTP Server.

     2

     If you use multiple NICs, specify a single interface in the ip option. For example, to use DHCP on a NIC that is named eno1, set ip=eno1:dhcp.

     3

     Specify the location of the initramfs file that you uploaded to your TFTP server.

2. Use the PXE or iPXE infrastructure to create the required compute machines for your cluster.

Procedure

1. Confirm that the cluster recognizes the machines:

   $ oc get nodes

   Example output

   NAME      STATUS    ROLES   AGE  VERSION
   master-0  Ready     master  63m  v1.26.0
   master-1  Ready     master  63m  v1.26.0
   master-2  Ready     master  64m  v1.26.0

   The output lists all of the machines that you created.

   Note

   The preceding output might not include the compute nodes, also known as worker nodes, until some CSRs are approved.

2. 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.

3. 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

   Because the CSRs rotate automatically, approve your CSRs within an hour of adding the machines to the cluster. If you do not approve them within an hour, the certificates will rotate, and more than two certificates will be present for each node. You must approve all of these certificates. After the client CSR is approved, the Kubelet creates a secondary CSR for the serving certificate, which requires manual approval. Then, subsequent serving certificate renewal requests are automatically approved by the machine-approver if the Kubelet requests a new certificate with identical 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 a request is not approved, then the oc exec, oc rsh, and oc logs commands cannot succeed, because a serving certificate is required when the API server 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 CSR was submitted by the node-bootstrapper service account in the system:node or system:admin groups, 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> 1

     1

     <csr_name> is 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 some CSRs are approved.

4. Now that your client requests are approved, you must 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
   ...

5. 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> 1

     1

     <csr_name> is 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

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

   $ oc get nodes

   Example output

   NAME      STATUS    ROLES   AGE  VERSION
   master-0  Ready     master  73m  v1.26.0
   master-1  Ready     master  73m  v1.26.0
   master-2  Ready     master  74m  v1.26.0
   worker-0  Ready     worker  11m  v1.26.0
   worker-1  Ready     worker  11m  v1.26.0

   Note

   It can take a few minutes after approval of the server CSRs for the machines to transition to the Ready status.