Chapter 11. Upgrading the Compute node operating system You can upgrade the operating system on all of your Compute nodes to RHEL 9.2, or upgrade some Compute nodes while the rest remain on RHEL 8.4. Important If your deployment includes hyperconverged infrastructure (HCI) nodes, you must upgrade all HCI nodes to RHEL 9. For more information about upgrading to RHEL 9, see Upgrading Compute nodes to RHEL 9.2 . For information about the duration and impact of this upgrade procedure, see Upgrade duration and impact . Prerequisites Review Planning for a Compute node upgrade . 11.1. Selecting Compute nodes for upgrade testing The overcloud upgrade process allows you to either: Upgrade all nodes in a role. Upgrade individual nodes separately. To ensure a smooth overcloud upgrade process, it is useful to test the upgrade on a few individual Compute nodes in your environment before upgrading all Compute nodes. This ensures no major issues occur during the upgrade while maintaining minimal downtime to your workloads. Use the following recommendations to help choose test nodes for the upgrade: Select two or three Compute nodes for upgrade testing. Select nodes without any critical instances running. If necessary, migrate critical instances from the selected test Compute nodes to other Compute nodes. Review which migration scenarios are supported: Source Compute node RHEL version Destination Compute node RHEL version Supported/Not supported RHEL 8 RHEL 8 Supported RHEL 8 RHEL 9 Supported RHEL 9 RHEL 9 Supported RHEL 9 RHEL 8 Not supported 11.2. Upgrading all Compute nodes to RHEL 9.2 Upgrade all your Compute nodes to RHEL 9.2 to take advantage of the latest features and to reduce downtime. Prerequisites If your deployment includes hyper-converged infrastructure (HCI) nodes, place hosts in maintenance mode to prepare the Red Hat Ceph Storage cluster on each HCI node for reboot. For more information, see Placing hosts in the maintenance mode using the Ceph Orchestrator in The Ceph Operations Guide . Important If you are using RHOSP version 17.1.3 or earlier, before you run the system upgrade, ensure that no guests are running on the Compute hosts. Any guests that are running go into an error state. To avoid this issue, either live migrate your workloads or shut them down. For more information about live migration, see Live migrating an instance in Configuring the Compute service for instance creation . Procedure Log in to the undercloud host as the stack user. Source the stackrc undercloud credentials file: In the container-image-prepare.yaml file, ensure that only the tags specified in the ContainerImagePrepare parameter are included, and the MultiRhelRoleContainerImagePrepare parameter is removed. For example: In the roles_data.yaml file, replace the OS::TripleO::Services::NovaLibvirtLegacy service with the OS::TripleO::Services::NovaLibvirt service that is required for RHEL 9.2. Include the -e system_upgrade.yaml argument and the other required -e environment file arguments in the overcloud_upgrade_prepare.sh script as shown in the following example: Run the overcloud_upgrade_prepare.sh script. Upgrade the operating system on the Compute nodes to RHEL 9.2. Use the --limit option with a comma-separated list of nodes that you want to upgrade. The following example upgrades the compute-0 , compute-1 , and compute-2 nodes. Replace <stack> with the name of your stack. Upgrade the containers on the Compute nodes to RHEL 9.2. Use the --limit option with a comma-separated list of nodes that you want to upgrade. The following example upgrades the compute-0 , compute-1 , and compute-2 nodes. 11.3. Upgrading Compute nodes to a Multi-RHEL environment You can upgrade a portion of your Compute nodes to RHEL 9.2 while the rest of your Compute nodes remain on RHEL 8.4. This upgrade process involves the following fundamental steps: Plan which nodes you want to upgrade to RHEL 9.2, and which nodes you want to remain on RHEL 8.4. Choose a role name for each role that you are creating for each batch of nodes, for example, ComputeRHEL-9.2 and ComputeRHEL-8.4 . Create roles that store the nodes that you want to upgrade to RHEL 9.2, or the nodes that you want to stay on RHEL 8.4. These roles can remain empty until you are ready to move your Compute nodes to a new role. You can create as many roles as you need and divide nodes among them any way you decide. For example: If your environment uses a role called ComputeSRIOV and you need to run a canary test to upgrade to RHEL 9.2, you can create a new ComputeSRIOVRHEL9 role and move the canary node to the new role. If your environment uses a role called ComputeOffload and you want to upgrade most nodes in that role to RHEL 9.2, but keep a few nodes on RHEL 8.4, you can create a new ComputeOffloadRHEL8 role to store the RHEL 8.4 nodes. You can then select the nodes in the original ComputeOffload role to upgrade to RHEL 9.2. Move the nodes from each Compute role to the new role. Upgrade the operating system on specific Compute nodes to RHEL 9.2. You can upgrade nodes in batches from the same role or multiple roles. Note In a Multi-RHEL environment, the deployment should continue to use the pc-i440fx machine type. Do not update the default to Q35. Migrating to the Q35 machine type is a separate, post-upgrade procedure to follow after all Compute nodes are upgraded to RHEL 9.2. For more information about migrating the Q35 machine type, see Updating the default machine type for hosts after an upgrade to RHOSP 17 . Use the following procedures to upgrade Compute nodes to a Multi-RHEL environment: Creating roles for Multi-RHEL Compute nodes Upgrading the Compute node operating system 11.3.1. Creating roles for Multi-RHEL Compute nodes Create new roles to store the nodes that you are upgrading to RHEL 9.2 or that are staying on RHEL 8.4, and move the nodes into the new roles. Procedure Create the relevant roles for your environment. In the role_data.yaml file, copy the source Compute role to use for the new role. Repeat this step for each additional role required. Roles can remain empty until you are ready to move your Compute nodes to the new roles. If you are creating a RHEL 8 role: Note Roles that contain nodes remaining on RHEL 8.4 must include the NovaLibvirtLegacy service. Replace <ComputeRHEL8> with the name of your RHEL 8.4 role. If you are creating a RHEL 9 role: Note Roles that contain nodes being upgraded to RHEL 9.2 must include the NovaLibvirt service. Replace OS::TripleO::Services::NovaLibvirtLegacy with OS::TripleO::Services::NovaLibvirt . Replace <ComputeRHEL9> with the name of your RHEL 9.2 role. Copy the overcloud_upgrade_prepare.sh file to the copy_role_Compute_param.sh file: Edit the copy_role_Compute_param.sh file to include the copy_role_params.py script. This script generates the environment file that contains the additional parameters and resources for the new role. For example: Replace <Compute_source_role> with the name of your source Compute role that you are copying. Replace <Compute_destination_role> with the name of your new role. Use the -o option to define the name of the output file that includes all the non-default values of the source Compute role for the new role. Replace <Compute_new_role_params.yaml> with the name of your output file. Run the copy_role_Compute_param.sh script: Move the Compute nodes from the source role to the new role: Note This tool includes the original /home/stack/tripleo-<stack>-baremetal-deployment.yaml file that you exported during the undercloud upgrade. The tool copies and renames the source role definition in the /home/stack/tripleo-<stack>-baremetal-deployment.yaml file. Then, it changes the hostname_format to prevent a conflict with the newly created destination role. The tool then moves the node from the source role to the destination role and changes the count values. Replace <stack> with the name of your stack. Replace <Compute_source_role> with the name of the source Compute role that contains the nodes that you are moving to your new role. Replace <Compute_destination_role> with the name of your new role. Replace <Compute-0> <Compute-1> <Compute-2> with the names of the nodes that you are moving to your new role. Reprovision the nodes to update the environment files in the stack with the new role location: Note The output baremetal-deployment.yaml file is the same file that is used in the overcloud_upgrade_prepare.sh file during overcloud adoption. Include any Compute roles that are remaining on RHEL 8.4 in the COMPUTE_ROLES parameter, and run the following script. For example, if you have a role called ComputeRHEL8 that contains the nodes that are remaining on RHEL 8.4, COMPUTE_ROLES = --role ComputeRHEL8 . Repeat this procedure to create additional roles and to move additional Compute nodes to those new roles. 11.3.2. Upgrading the Compute node operating system Upgrade the operating system on selected Compute nodes to RHEL 9.2. You can upgrade multiple nodes from different roles at the same time. Prerequisites Ensure that you have created the necessary roles for your environment. For more information about creating roles for a Multi-RHEL environment, see Creating roles for Multi-RHEL Compute nodes . Important If you are using RHOSP version 17.1.3 or earlier, before you run the system upgrade, ensure that no guests are running on the Compute hosts. Any guests that are running go into an error state. To avoid this issue, either live migrate your workloads or shut them down. For more information about live migration, see Live migrating an instance in Configuring the Compute service for instance creation . Procedure In the skip_rhel_release.yaml file, set the SkipRhelEnforcement parameter to false : Include the -e system_upgrade.yaml argument and the other required -e environment file arguments in the overcloud_upgrade_prepare.sh script as shown in the following example: Include the system_upgrade.yaml file with the upgrade-specific parameters (-e). Include the environment file that contains the parameters needed for the new role (-e). Replace <Compute_new_role_params.yaml> with the name of the environment file you created for your new role. If you are upgrading nodes from multiple roles at the same time, include the environment file for each new role that you created. Optional: Migrate your instances. For more information on migration strategies, see Migrating virtual machines between Compute nodes and Preparing to migrate . Run the overcloud_upgrade_prepare.sh script. Upgrade the operating system on specific Compute nodes. Use the --limit option with a comma-separated list of nodes that you want to upgrade. The following example upgrades the computerhel9-0 , computerhel9-1 , computerhel9-2 , and computesriov-42 nodes from the ComputeRHEL9 and ComputeSRIOV roles. Replace <stack> with the name of your stack. Upgrade the containers on the Compute nodes to RHEL 9.2. Use the --limit option with a comma-separated list of nodes that you want to upgrade. The following example upgrades the computerhel9-0 , computerhel9-1 , computerhel9-2 , and computesriov-42 nodes from the ComputeRHEL9 and ComputeSRIOV roles.

Commands:
source ~/stackrc
parameter_defaults: ContainerImagePrepare: - tag_from_label: "{version}-{release}" set: namespace: name_prefix: name_suffix: tag: rhel_containers: false neutron_driver: ovn ceph_namespace: ceph_image: ceph_tag:
openstack overcloud upgrade prepare --yes ... -e /home/stack/system_upgrade.yaml ...
openstack overcloud upgrade run --yes --tags system_upgrade --stack <stack> --limit compute-0,compute-1,compute-2
openstack overcloud upgrade run --yes --stack <stack> --limit compute-0,compute-1,compute-2
name: <ComputeRHEL8> description: | Basic Compute Node role CountDefault: 1 rhsm_enforce_multios: 8.4 ServicesDefault: - OS::TripleO::Services::NovaLibvirtLegacy
name: <ComputeRHEL9> description: | Basic Compute Node role CountDefault: 1 ServicesDefault: - OS::TripleO::Services::NovaLibvirt
cp overcloud_upgrade_prepare.sh copy_role_Compute_param.sh
/usr/share/openstack-tripleo-heat-templates/tools/copy_role_params.py --rolename-src <Compute_source_role> --rolename-dst <Compute_destination_role> -o <Compute_new_role_params.yaml> -e /home/stack/templates/internal.yaml -e /usr/share/openstack-tripleo-heat-templates/environments/services/neutron-ovs.yaml -e /home/stack/templates/network/network-environment.yaml -e /home/stack/templates/inject-trust-anchor.yaml -e /home/stack/templates/hostnames.yml -e /usr/share/openstack-tripleo-heat-templates/environments/ceph-ansible/ceph-ansible.yaml -e /home/stack/templates/nodes_data.yaml -e /home/stack/templates/debug.yaml -e /home/stack/templates/firstboot.yaml -e /home/stack/overcloud-params.yaml -e /home/stack/overcloud-deploy/overcloud/overcloud-network-environment.yaml -e /home/stack/overcloud_adopt/baremetal-deployment.yaml -e /home/stack/overcloud_adopt/generated-networks-deployed.yaml -e /home/stack/overcloud_adopt/generated-vip-deployed.yaml -e /usr/share/openstack-tripleo-heat-templates/environments/nova-hw-machine-type-upgrade.yaml -e ~/containers-prepare-parameter.yaml
sh /home/stack/copy_role_Compute_param.sh
python3 /usr/share/openstack-tripleo-heat-templates/tools/baremetal_transition.py --baremetal-deployment /home/stack/tripleo-<stack>-baremetal-deployment.yaml --src-role <Compute_source_role> --dst-role <Compute_destination_role> <Compute-0> <Compute-1> <Compute-2>
openstack overcloud node provision --stack <stack> --output /home/stack/overcloud_adopt/baremetal-deployment.yaml /home/stack/tripleo-<stack>-baremetal-deployment.yaml
python3 /usr/share/openstack-tripleo-heat-templates/tools/multi-rhel-container-image-prepare.py USD{COMPUTE_ROLES} --enable-multi-rhel --excludes collectd --excludes nova-libvirt --minor-override "{USD{EL8_TAGS}USD{EL8_NAMESPACE}USD{CEPH_OVERRIDE}USD{NEUTRON_DRIVER}\"no_tag\":\"not_used\"}" --major-override "{USD{EL9_TAGS}USD{NAMESPACE}USD{CEPH_OVERRIDE}USD{NEUTRON_DRIVER}\"no_tag\":\"not_used\"}" --output-env-file /home/stack/containers-prepare-parameter.yaml
parameter_defaults: SkipRhelEnforcement: false
openstack overcloud upgrade prepare --yes -e /home/stack/system_upgrade.yaml -e /home/stack/<Compute_new_role_params.yaml>
openstack overcloud upgrade run --yes --tags system_upgrade --stack <stack> --limit computerhel9-0,computerhel9-1,computerhel9-2,computesriov-42
openstack overcloud upgrade run --yes --stack <stack> --limit computerhel9-0,computerhel9-1,computerhel9-2,computesriov-42