About customizing a pattern
One of the major goals of the Validated Patterns development process is to create modular, customizable demos. The Multicloud Gitops is just an example of a pattern managing multiple clusters in a GitOps fashion. It contains a very simple config-demo application, which prints out a secret that was injected into the vault through an out-of-band mechanism.
You can customize this demo in different ways.
Split the config-demo across hub and regional clusters
Currently hub and regional clusters are reusing the exact same helm chart found at charts/all/config-demo. The first customization step could be to split the demo app in two separate charts: one in charts/hub/config-demo and one in charts/region/config-demo. Once charts/all/config-demo has been copied to charts/hub/config-demo and charts/region/config-demo, you need to include them in the respective values-hub.yaml and values-region-one.yaml, respectively.
After completing this configuration, you can start customizing the two apps and make them output a different web page entirely depending if the pod is running on the hub or on the cluster.
Rest API addition
After splitting the charts, you could implement a small REST API server on the hub. This API could serve read-only values out to anyone and could provide some update write-APIs only if the client provides a secret, for example, by using the X-API-KEY mechanism. You can tweak the config-demo application to communicate to the hub and use a vault-injected secret as the X-API-KEY. So the hub would possess the key through the External-Secrets generated kubernetes secret and the regional app would possess that same secret via the RHACM policy pushing out secrets via the {{hub fromSecret}} mechanism.
