Support HTTPRouteFilter as a Backend Filter

[arkodg]

Description:

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

Gateway API supports specifying filters per backendRefs https://gateway-api.sigs.k8s.io/reference/spec/#gateway.networking.k8s.io%2fv1.HTTPBackendRef which allow filter definitions to kick in after backend selection

Envoy Gateway has an extended filter called HTTPRouteFilter . This will soon support a credentialInjection option #5312.

If this filter can be applied per BackendRef we can enable some more use cases like injecting different API Keys based on the backendRef

[optional Relevant Links:]

Any extra documentation required to understand the issue.

[arkodg]

cc @mathetake @missBerg @yuzisun

[zhaohuabing]

@arkodg It looks like EG can't support Backend Filter if we don't change the logic for generating Clusters. Envoy supports upstream filter via the Cluster configuration, but EG creates Cluster per RouteRule-not per Backend. To support Backend Filter, EG would need to create a Cluster per Backend.

[arkodg]

should be possible

gateway/internal/xds/translator/translator.go

Line 589 in ce8b6bd

if !needsClusterPerSetting(httpRoute.Destination.Settings) {

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days.