Epic Goal

I want to install OpenShift with IPI on baremetal I need to distribute my control plane and compute nodes across multiple subnets.

Why is this important?

Customers require using multiple logical availability zones to define their architecture and topology for their datacenter. OpenShift clusters are expected to be suitable for this topology and fit in the high availability and disaster recovery plans they designed their datacenter with.

Customers want the benefits of IPI and automated installations and avoid UPI.

Previous Work

Workers on separate subnets

We can already deploy compute nodes on separate subnets by preventing the built-in LBs from running on the compute nodes. This is documented for bare metal only for the Remote Worker Nodes use case: https://docs.openshift.com/container-platform/4.11/installing/installing_bare_metal_ipi/ipi-install-installation-workflow.html#configure-network-components-to-run-on-the-control-plane_ipi-install-installation-workflow

This procedure works on vSphere too, albeit not documented.

Scenarios

1. vSphere: I can define 3 or more networks in vSphere and distribute my masters and workers across them. I can configure an external load balancer for the VIPs.

Acceptance Criteria

• Can place compute nodes on multiple subnets with IPI installations
• Can place control plane nodes on multiple subnets with IPI installations

Done Checklist

• CI - CI is running, tests are automated and merged.
• Release Enablement <link to Feature Enablement Presentation>
• DEV - Upstream code and tests merged: <link to meaningful PR or GitHub Issue>
• DEV - Upstream documentation merged: <link to meaningful PR or GitHub Issue>
• DEV - Downstream build attached to advisory: <link to errata>
• QE - Test plans in Polarion: <link or reference to Polarion>
• QE - Automated tests merged: <link or reference to automated tests>
• DOC - Downstream documentation merged: <link to meaningful PR>