Installing a three-node cluster on VMC

In OKD version 4.13, you can install a three-node cluster on your VMware vSphere instance by deploying it to VMware Cloud (VMC) on AWS. A three-node cluster consists of three control plane machines, which also act as compute machines. This type of cluster provides a smaller, more resource efficient cluster, for cluster administrators and developers to use for testing, development, and production.

You can install a three-node cluster using either installer-provisioned or user-provisioned infrastructure.

Configuring a three-node cluster

You configure a three-node cluster by setting the number of worker nodes to 0 in the install-config.yaml file before deploying the cluster. Setting the number of worker nodes to 0 ensures that the control plane machines are schedulable. This allows application workloads to be scheduled to run from the control plane nodes.

Prerequisites

• You have an existing install-config.yaml file.

Procedure

1. Set the number of compute replicas to 0 in your install-config.yaml file, as shown in the following compute stanza:

   compute:
   - name: worker
     platform: {}
     replicas: 0

2. If you are deploying a cluster with user-provisioned infrastructure:

   • Configure your application ingress load balancer to route HTTP and HTTPS traffic to the control plane nodes. In a three-node cluster, the Ingress Controller pods run on the control plane nodes. For more information, see the “Load balancing requirements for user-provisioned infrastructure”.

   • After you create the Kubernetes manifest files, make sure that the spec.mastersSchedulable parameter is set to true in cluster-scheduler-02-config.yml file. You can locate this file in <installation_directory>/manifests. For more information, see “Creating the Kubernetes manifest and Ignition config files” in “Installing a cluster on VMC with user-provisioned infrastructure”.

   • Do not create additional worker nodes.

Example cluster-scheduler-02-config.yml file for a three-node cluster

apiVersion: config.openshift.io/v1
kind: Scheduler
metadata:
  creationTimestamp: null
  name: cluster
spec:
  mastersSchedulable: true
  policy:
    name: ""
status: {}

Next steps

• Installing a cluster on VMC with customizations

• Installing a cluster on VMC with user-provisioned infrastructure