Questions about HTTPRequestRedirectFilter

[pleshakov]

Hi,

I've got a few questions about the HTTPRequestRedirectFilter behavior. I wonder if there are some guidelines around that behavior.

(1)
In the example here https://gateway-api.sigs.k8s.io/guides/http-redirect-rewrite/#redirects we have:

. . .
  rules:
    - filters:
      - type: RequestRedirect
        requestRedirect:
          scheme: https
          statusCode: 301
      backendRefs:
      - name: example-svc
        weight: 1
        port: 80

where one backendRef is configured. However, since the redirect is not conditional, the data plane will never proxy to the backend -- it will always redirect.

That brings a few questions:

(a) Should a Gateway implementation report to the user that the backendRefs will be ignored?

(b) Considering that a Gateway implementation will ignore the backendRefs, should it validate the backendRefs? For example, insure that the backend service exists? Or can a Gateway implementation skip the validation of ignored backendRefs?

(c) Is it necessary to have the backendRefs? Would it make sense to remove them from the example?

(2)
For a few fields in HTTPRequestRedirectFilter , there is a validation requirement like below:

	//
	// Unknown values here must result in the implementation setting the
	// Attached Condition for the Route to `status: False`, with a
	// Reason of `UnsupportedValue`.

(from https://github.com/kubernetes-sigs/gateway-api/blob/v0.5.0/apis/v1beta1/httproute_types.go#L829-L831)

(a) If a Gateway implementation finds that a field is invalid in an HTTPRequestRedirectFilter and it sets Attached Condition for the Route to status: False , does this mean all routing rules in the route will be ignored or just the affected rule?

(b) What status code the data plane shall return?

[jpeach]

(a) Should a Gateway implementation report to the user that the backendRefs will be ignored?

Maybe, as a quality of implementation feature. I don't think the spec needs to require this though.

(b) Considering that a Gateway implementation will ignore the backendRefs, should it validate the backendRefs?

Yes, as a matter of principal, everything should be validated.

(c) Is it necessary to have the backendRefs?

Not AFAICT.

Would it make sense to remove them from the example?

Probably.

(a) If a Gateway implementation finds that a field is invalid in an HTTPRequestRedirectFilter and it sets Attached Condition for the Route to status: False , does this mean all routing rules in the route will be ignored or just the affected rule?

My opinion is that you should drop the route. Anything less than that is hard to understand and liable to have unexpected results.

(b) What status code the data plane shall return?

If the gateway drops the route, probably serving a 503 on that route is the best option.