Use Kubernetes custom resource definitions

[tazjin]

Kubernetes has support for third-party resources.

Ideally instead of using service annotations this controller would watch a custom third-party CertificateRequest object and create secrets based on that to decouple consuming services from the certificates and to make certificates cluster-native resources.

Currently the Java SDK for Kubernetes developed by Fabric8 does not support third-party resources. This issue is tracked in fabric8io/kubernetes-client#299

[tazjin]

FTR, as of Kubernetes 1.7 TPRs are now CDRs.

[munnerz]

Hey - we've implemented a Certificates API over in cert-manager.

Any feedback on the direction we've taken would be greatly appreciated. If you'd like to discuss ways this could potentially be reused and/or made into a shared resource, I'm always around for discussion!