Relax protocol matching requirement between Gateway API listener and Route

[wondersd]

What would you like to be added:

remove or allow to disable this check

https://github.com/kubernetes-sigs/external-dns/blob/master/source/gateway.go#L318-L321

// Confirm that the Listener and Route protocols match.
if !gwProtocolMatches(rt.Protocol(), lis.Protocol) {
  continue
}

Or to extend gwProtocolMatches to include considering TLS and TCP the same:

https://github.com/kubernetes-sigs/external-dns/blob/master/source/gateway.go#L476-L486

// gwProtocolMatches returns whether a and b are the same protocol,
// where HTTP and HTTPS are considered the same.
func gwProtocolMatches(a, b v1beta1.ProtocolType) bool {
	if a == v1beta1.HTTPSProtocolType {
		a = v1beta1.HTTPProtocolType
	}
	if b == v1beta1.HTTPSProtocolType {
		b = v1beta1.HTTPProtocolType
	}
	return a == b
}

Why is this needed:

When using a Gateway as a terminating proxy for TCP connections as per https://gateway-api.sigs.k8s.io/guides/tls/#clientserver-and-tls

TLS | Terminate | TCPRoute

The protocols will be mixed between the listener and route (TLS and TCP). This check seems to prevent what is otherwise considered valid usages from having DNS records generated.

{"level":"debug","msg":"No endpoints could be generated from TCPRoute ...","time":"..."}
{"level":"debug","msg":"Gateway ... section \"...\" does not match TCPRoute ... hostnames [\"...\" \"\"]","time":"..."}

Given

apiVersion: gateway.networking.k8s.io/v1beta1
kind: Gateway
metadata:
  name: ...
  namespace: ...
spec:
  gatewayClassName: ...
  listeners:
  - allowedRoutes:
      kinds:
      - group: gateway.networking.k8s.io
        kind: TCPRoute
      namespaces:
        from: Same
    hostname: ...
    name: ...
    port: ...
    protocol: TLS
    tls:
      certificateRefs:
      - group: ""
        kind: Secret
        name: ...
      mode: Terminate
---
apiVersion: gateway.networking.k8s.io/v1alpha2
kind: TCPRoute
metadata:
  labels:
    external-dns.alpha.kubernetes.io/hostname: ...
  name: ...
  namespace: ...
spec:
  parentRefs:
  - group: gateway.networking.k8s.io
    kind: Gateway
    name: ...
    sectionName: ...
  rules:
  - backendRefs:
    - group: ""
      kind: Service
      name: ...
      port: ...
      weight: 1

[matiza5]

Faced the same problem. TLS protocol and TCPRoute combination should be supported, as it is supported in GatewayAPI.

[zs-ko]

Faced the same problem. TLS termination with TCPRoute

[zs-ko]

fixed the issue and created a pr. Should also add more test to TCPRoute to reflect HTTPRoute testing.
Here is a image that can be used until it's merged
https://github.com/users/zs-ko/packages/container/package/external-dns