Dell APEX Cloud Platform for RedHat OpenShift: How to enable Dedicated Control Plane

Prerequisites

• You have a Linux workstation that can access the cluster.
• You can access the cluster as a user with cluster-admin role.
• The cluster consists of at least 5 compute nodes (3-node consolidated cluster and 2 dedicated worker nodes). 
• OpenShift Service Mesh has been configured for the cluster.
• The OC CLI tool 4.10 or above version has been installed.
  • Go to Getting started with the OpenShift CLI and follow link to the OpenShift Platform download page (you will need a login to access).
  • Select a 4.13.x for RHEL 8 as RHEL 9 isn't available yet.
• Download the zip file attached in this KB, rename the zip file to "enable-dedicated-control-plane.zip"

How to Enable Dedicated Control Plane

Note:

1. If there are customer workloads running on Control Plane node, they might be migrated to Worker node after running this procedure.
2. After a control plane is converted to dedicated, it will have a "NoSchedule" taint which will refuse a pod to be scheduled unless that pod has a matching toleration. For the customer workloads need to be scheduled to control plane, please follow this guide to handle them: https://docs.openshift.com/container-platform/4.13/nodes/scheduling/nodes-scheduler-taints-tolerations.html#nodes-scheduler-taints-tolerations-about_nodes-scheduler-taints-tolerations.

Steps:

1. On the Linux workstation that can access the cluster, create an empty working directory and copy the zip file "enable-dedicated-control-plane.zip" to the directory.
2. Run the following commands to enable dedicated control plane. 

$ unzip enable-dedicated-control-plane.zip && cd enable-dedicated-control-plane

$ chmod +x enable-dedicated-control-plane.sh

$ ./enable-dedicated-control-plane.sh -u <user> -p <password> -c <cluster_name.top_level_domain>

Verify the Enablement

From the Red Hat OpenShift Container Platform console:

1. Select Compute -> Nodes from the left navigation bar. Confirm that all control-plane nodes do not have the "worker" role.
2. Select Workloads -> Pods from the left navigation bar. Confirm that all pods in all namespaces starting with "dell-acp" are in either the "Running" or "Completed" state.
3. Select Workloads -> Pods from the left navigation bar. Confirm that all customer workloads are working as expected.