Review cluster-level privileges to create the ClusterDomainClaim resource

[Milstein]

Dear NERC,
Could you help us get custom domain names working for KNative serving in the namespace chris-3114b1 and the domain name blt.chrisproject.org? I believe it requires cluster-level privileges to create the ClusterDomainClaim resource.
https://knative.dev/docs/serving/services/custom-domains/

Coincidentally, if we had a solution for using k8s Ingress with ExternalName services (issue #004354), we could do a workaround of creating an ingress for the knative-generated ExternalName service.

[joachimweyl]

@Milstein can you gather more information about this? At this time it does not seem worth it to put the level of work into this that would be required.