How to use Gateway API with Kong on GKE?

Question

Goal

I'm trying to use the Kubernetes Gateway API with Kong deployed on Google Kubernetes Engine (GKE).
I'd like to have some sort of guide or a set of steps to properly setup and use the Gateway API in our GKE cluster, in order to be able to create a HTTPRoute and make Kong handle the related traffic.

Setup

We're deploying Kong through an Helm chart (kong/ingress dependency). Here's the Chart.yaml:

[...]

dependencies:
  - name: ingress
    alias: kong-ingress
    version: 0.12.0
    repository: https://charts.konghq.com

Here's the values.yaml:

kong-ingress:

  controller:
    enabled: true

  gateway:
    enabled: true

    proxy:
      loadBalancerIP: "X.X.X.X" # External static IP from GKE

    certificates:
      enabled: true
      issuer: "kong-api-gateway" # We're also creating an Issuer based on letsencrypt

      proxy:
        enabled: true
        commonName: "our.hostname.com"

      admin:
        enabled: true
        commonName: "our.hostname.com"
        issuer: "kong-api-gateway"

      portal:
        enabled: false

      cluster:
        enabled: false

Test

I've been able to deploy the Kong echo service:

# Deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: echo
  name: echo
spec:
  replicas: 1
  selector:
    matchLabels:
      app: echo
  strategy: {}
  template:
    metadata:
      labels:
        app: echo
    spec:
      containers:
        - image: kong/go-echo:latest
          name: echo
          ports:
            - containerPort: 1025
            - containerPort: 1026
            - containerPort: 1027
          env:
            - name: NODE_NAME
              valueFrom:
                fieldRef:
                  fieldPath: spec.nodeName
            - name: POD_NAME
              valueFrom:
                fieldRef:
                  fieldPath: metadata.name
            - name: POD_NAMESPACE
              valueFrom:
                fieldRef:
                  fieldPath: metadata.namespace
            - name: POD_IP
              valueFrom:
                fieldRef:
                  fieldPath: status.podIP
          resources: {}
---
# Service
apiVersion: v1
kind: Service
metadata:
  labels:
    app: echo
  name: echo
spec:
  ports:
    - port: 1025
      name: tcp
      protocol: TCP
      targetPort: 1025
    - port: 1026
      name: udp
      protocol: TCP
      targetPort: 1026
    - port: 1027
      name: http
      protocol: TCP
      targetPort: 1027
  selector:
    app: echo

And expose it using an Ingress resource:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: echo
  namespace: kong-api-gateway
  annotations:
    konghq.com/strip-path: 'true'
spec:
  ingressClassName: kong
  rules:
  - http:
      paths:
      - path: /echo
        pathType: ImplementationSpecific
        backend:
          service:
            name: echo
            port:
              number: 1027
    host: 'our.hostname.com'

Therefore, by sending a GET request to https://our.hostname.com/echo I get a response and the traffic is handled correctly by the Kong gateway:

$ curl -i -k -s https://our.hostname.com/echo
HTTP/1.1 200 OK
Content-Type: text/plain; charset=utf-8
Content-Length: 183
Connection: keep-alive
Date: Tue, 05 Mar 2024 09:28:42 GMT
X-Kong-Upstream-Latency: 1
X-Kong-Proxy-Latency: 0
Via: kong/3.6.0
X-Kong-Request-Id: 37cdd90730c6595e2364f736e74a6146

Welcome, you are connected to node gke-test-europe-west1-default-pool-d1b60670-qqbd.
Running on Pod echo-74c66b778-44j9l.
In namespace kong-api-gateway.
With IP address X.X.X.X.

Problem

The Kong Ingress Controller documentation for the GKE deployment (docs.konghq.com) doesn't provide any information about the Gateway API.

What would be the steps I need to perform to utilize them?

Here's the Gateway api-resources installed in our cluster:

$ kubectl api-resources | { head -1; grep gateway; }
NAME                 SHORTNAMES   APIVERSION                          NAMESPACED   KIND
gatewayclasses       gc           gateway.networking.k8s.io/v1beta1   false        GatewayClass
gateways             gtw          gateway.networking.k8s.io/v1beta1   true         Gateway
httproutes                        gateway.networking.k8s.io/v1beta1   true         HTTPRoute
referencegrants      refgrant     gateway.networking.k8s.io/v1beta1   true         ReferenceGrant
gcpgatewaypolicies                networking.gke.io/v1                true         GCPGatewayPolicy

HTTPRoute example:

# Route /echo
apiVersion: gateway.networking.k8s.io/v1beta1
kind: HTTPRoute
metadata:
  name: echo
  annotations:
    konghq.com/strip-path: 'true'
spec:
  parentRefs:
  # Gateway reference
  - name: kong
  rules:
  - matches:
    - path:
        type: PathPrefix
        value: /echo
    backendRefs:
    - name: echo
      kind: Service
      port: 1027

Answer 1

Any HTTPRoute will be reconciled by the Kong Ingress Controller automatically if the Gateway API CRDs are in the cluster when KIC starts. You do not need to enable anything

If you're using other route types you may need to enable the GatewayAlpha feature gate with kubectl set env -n kong deployment/kong-controller CONTROLLER_FEATURE_GATES="GatewayAlpha=true" -c ingress-controller