Proposed title of this feature request

To to add multiple platform.azure.armEndpoint for capicity reasons at Azure Stack Hub installation level

2. What is the nature and description of the request?

Without this use case, there is no possibility to add more azure resource manager endpints and hence the cluster would be limited.

3. Why does the customer need this? (List the business requirements here)

A cluster is installed in Azure Stack Hub environment. However, the current Azure Stack Hub rack had reached the maximum capacity, the customer intend to increase capacity by adding additional rack which will result in additional different ARM endpoint from the original ARM endpoint.

Based on the OCP installation documentation on Azure Stack Hub using UPI in the URL:

https://docs.openshift.com/container-platform/4.14/installing/installing_azure_stack_hub/installing-azure-stack-hub-user-infra.html#installation-azure-stack-hub-config-yaml_installing-azure-stack-hub-user-infra

In the install-config.yaml configuration attached, only one armEndPoint can be included. The question is how to add multiple armEndPoints to the OCP 4.12 cluster? Besides, the customer will be using different Azure resource group and different Azure virtual network when they add the new Azure Stack Hub rack.

It seems it was added here: 
https://github.com/openshift/installer/pull/4799/files#diff-383bd473843d54f24fdea79ed74893eccb34e213fda1595142bc3ac1d206313f
4. List any affected packages or components.

OpenShift Installer - Azure Stack