External name services dont work with kind, CoreDNS CM is blocking it by default in all versions

[Joseluismantilla]

What happened:

Nginx ingress controller with external names doesnt work with Kind.

What you expected to happen:

Services (whether ExternalName, ClusterIP, etc.) in Kubernetes, by default, live in the namespace where they are defined.
When resolving DNS in other namespaces, Kubernetes must construct addresses like ..svc.cluster.local, which ExternalName services don’t always support without additional DNS resolution steps.

How to reproduce it (as minimally and precisely as possible):

Follow the official steps at https://kind.sigs.k8s.io/docs/user/ingress/ and try to reach an external name service created in the nginx-ingress namespace that connect to services in other namespaces.

Anything else we need to know?:

The CoreDNS configmap by default is blocking the cluster DNS for the external names services.

Environment:

• kind version: (use kind version): all
• Runtime info: (use docker info, podman info or nerdctl info): podman version 4.9.3
• OS (e.g. from /etc/os-release): Windows 11 & linux distros on WSL2
• Kubernetes version: (use kubectl version): NA
• Any proxies or other special environment settings?: NA

[BenTheElder]

ExternalName is typically used to point at external DNS entries via CNAME ... (It can also have a manually specified IP)

Follow the official steps at https://kind.sigs.k8s.io/docs/user/ingress/ and try to reach an external name service created in the nginx-ingress namespace that connect to services in other namespaces.

What does this externalname service point to, exactly? What does it have to do with ingress? How is it "[...] connect to services in other namespaces [...]" ?