Deprecate and remove TCP/UDP forwarding

[rikatz]

Ingress API was originally built to allow routing of HTTP (L7) traffic. Due the time, some additional features, like supporting TCP and UDP forwarding has been added.

The maintenance of these APIs became a burden to migrate to NJS, and created a bunch of different issues on ingress-nginx. Officially, the way to route TCP/UDP traffic on a Kubernetes cluster should be made on 2 different ways:

• Using a Service (generally of type LoadBalancer or NodePort)
• Using GatewayAPI TCPRoute

As part of the GatewayAPI evolution, I would like to deprecate and remove TCP and UDP forwarding from current ingress-nginx as part of the next minor release and focus the current ingress-nginx implementation on L7/HTTP routing.

/kind deprecation

[k8s-ci-robot]

This issue is currently awaiting triage.

If Ingress contributors determines this is a relevant issue, they will accept it by applying the triage/accepted label and provide further guidance.

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[aojea]

/cc @aojea @robscott

[tao12345666333]

We do encounter a lot of TCP/UDP related questions in our issues list and user channel.

https://github.com/kubernetes/ingress-nginx/issues?page=2&q=is%3Aissue+is%3Aopen+tcp

[rikatz]

Yes, but it doesn't mean we should be supporting it :)

[github-actions]

This is stale, but we won't close it automatically, just bare in mind the maintainers may be busy with other tasks and will reach your issue ASAP. If you have any question or request to prioritize this, please reach #ingress-nginx-dev on Kubernetes Slack.

[strongjz]

This is a low priority and most likely will not make the cut to deprecations.

This functionality will be implemented in InGate and the Gateway API, not in ingress.

More details here https://www.youtube.com/watch?v=KLwsV6_DntA