Support IP as host in rules to allow for IP certificates TLS on routes #4446
Description
see kubernetes/kubernetes#136095 (comment) for reference of dicussion about the similar issue with Ingress resource.
What would you like to be added:
LetsEncrypt now supports IP certs (certificates valid for an IP address rather than a domain name), but for the TLS certificate to be served by the Load Balancer, the host needs to match the host in the rule exactly. However when the cert is for an IP address, the host needs to be an IP, which is currently not really supported. According to my research of the code, IPv4 would work because the validation RegEx would allow it, then it is up to the controller to support the behavior. Many controller may support IPv4 as host, but IPv6 will not work (first it would fial the validation, but also the controller would likely not support IPv6 as hostname in the first place.
Why this is needed:
To be able to use IP certificate and apply TLS certs to routes.