How to configure a custom subnet prefix size for VKS Cluster deployed via VCF Automation 9.1.0

Products

• VMware vSphere Kubernetes Service
• VCF Automation

Issue/Introduction

By default, when deploying a vSphere Kubernetes Service (VKS) Cluster via VCF Automation, the primary node network prefix size is assigned as /27.
A /27 subnet provides 29 usable IP addresses for Kubernetes nodes. To deploy larger-scale VKS Guest Clusters and prevent IP address exhaustion during node scale-out or rolling updates, administrators need to specify a larger subnet size (e.g., /26, /24).

This article provides step-by-step guidance on how to change the network prefix size and deploy a VKS Cluster with a custom subnet prefix using the SubnetSet feature in VCF Automation 9.1.0.

Environment

• VCF Automation 9.1.0
• vSphere Kubernetes Service

Resolution

• 1. Log in to the VCF Automation Organization Portal.
• 2. Navigate to Build & Deploy --> Network --> SubnetSets

• 3. Click + NEW SUBNETSET and configure the following:
  • Name: Enter a name for the SubnetSet
  • Access Mode: Private - VPC
  • Size: Select your desired size
  • DHCP: None

• 4. Deploy the VKS Cluster
  • Go to Build & Deploy --> Kubernetes --> click + CREATE.
  • Configuration Type: Select "Custom Configuration"
  • General Settings --> Network --> Node Network --> Primary | eth0 --> Check "Use custom primary network"
  • Network: Select the created <SubnetSet>

• 5. Follow the remaining steps of the wizard and click "FINISH".