Add e2e test for weighted backend

[Xunzhuo]

Description:

Describe the desired behavior, what scenario it enables and how it
would be used.

Set up e2e test for weighted backend, prevent #2187

[ShyunnY]

@Xunzhuo Hello Xunzhuo, I'm interested in this issue. Could you please provide more information?

[arkodg]

Hey @ShyunnY the conformance tests live in https://github.com/envoyproxy/gateway/tree/main/test/e2e
Here's the feature we need to add an e2e for https://gateway-api.sigs.k8s.io/guides/traffic-splitting/#http-traffic-splitting

[ShyunnY]

@arkodg
I encountered some problems when writing e2e tests: I need to obtain the pod information in the backend response body as a traffic identifier to calculate the weight of routing to different backends under given traffic. But the CapturedResponse obtained by suite.RoundTripper.CaptureRoundTrip(req) seems to only contain response metadata. I can't determine which backend this traffic is routed to.
Currently I want to use the net.http package to solve this problem. Do you have a better way?

[zirain]

@arkodg I encountered some problems when writing e2e tests: I need to obtain the pod information in the backend response body as a traffic identifier to calculate the weight of routing to different backends under given traffic. But the CapturedResponse obtained by suite.RoundTripper.CaptureRoundTrip(req) seems to only contain response metadata. I can't determine which backend this traffic is routed to. Currently I want to use the net.http package to solve this problem. Do you have a better way?

will stats help?