CFP: Support GRPCRoute in Cilium Gateway API

[sayboras]

Cilium Feature Proposal

The first cut for Gateway API was done in #21749, however, we have a couple of follow-up tasks to support more features from Gateway API upstream.

This is to track the work to support GRPCRoute.

Goals

Based on the progress and code re-usability introduced in TLSRoutes we should build a similar implementation of GRPCRoute. This route should re-use logic from both TLS and HTTP routes to route gRPC.

To implement it we should re-use the Envoy logic as an GRPCRoute can be attached to a HTTP(S) Gateway, we can therefore re-use that for TLS termination. Preferably it should use gRPC specific routing in Envoy where possible.

Proposed Solution

TBD

Tasks

• Add required reconcile functions to validate GRPCRoute
  • Validate against hostname re-use between HTTP and gRPC
• Add a translator module for GRPCRoutes rules to Envoy rules
  • Consider a gRPC Web filter https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_filters/grpc_web_filter & https://github.com/grpc/grpc-web/blob/master/net/grpc/gateway/examples/echo/envoy.yaml
• Handle edge cases according to spec (TBD)
• Validate required CRDs will be installed
• Pass conformance tests
• Awesome documentation!

[github-actions]

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[networkop]

Need to test this against our hubble-ui as an additional validation check

[sayboras]

Addressed by #28464