1. Proposed title of this feature request

Avoid the default ingress controller serving routes for all projects when using router sharding.

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

When configuring router sharding, it may be desired to serve specific namespaces only by specific ingress controllers. However, with the default configuration, the default ingress Controller will still serve all routes in every namespace due to the absence of a namespaceSelector or routeSelector configuration for this IngressController.

We found this kcs where we can configure namespaceSelector, and it is working fine, but as per the customer, it is a manual effort and too inconvenient  to exclude application namespaces from default IngressController every time a namespace for an application is created. We are raising RFE to add the capability so during the router sharding default ingress controller stop serving all the routes for customers namespaces. Especially when Ingresses are tied to specific IngressClasses.
https://access.redhat.com/solutions/5097511

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

Customers using router sharding rely on this functionality and thus require the route to be exposed to a custom router; otherwise, communication won't work as expected. Since OpenShift 4 has the concept of router sharding, it's expected that the request should be served from the specified ingress controller and  the default ingressController excluded for those Ingresses .

4. List any affected packages or components.

OpenShift Networking