Ingress packed listener, routing and TLS into one object, and anything beyond host and path became a controller-specific annotation. The Gateway API splits the job into three objects with three owners.

Three objects

kubectl get gatewayclass

NAME      CONTROLLER                      ACCEPTED   AGE
traefik   traefik.io/gateway-controller   True       12d

The same Traefik that serves Ingress implements this class.

A Gateway and a route

apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: market-gateway
spec:
  gatewayClassName: traefik
  listeners:
    - name: web
      port: 80
      protocol: HTTP
---
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: shop
spec:
  parentRefs:
    - name: market-gateway
  hostnames: ["shop.example"]
  rules:
    - matches:
        - path:
            type: PathPrefix
            value: /monsters
      backendRefs:
        - name: market-api
          port: 8080
    - backendRefs:
        - name: market-web
          port: 80

The route attaches to the Gateway through parentRefs. Its hostnames filter first; then each rule's matches (path, and in full implementations headers, methods and query params) picks backendRefs. A rule with no matches matches every path. Traffic arrives the same way as before:

curl -H "Host: shop.example" http://10.0.0.10/monsters

What it adds

Beyond what Ingress does, routes can split traffic by weight between two backends, match on headers, and be attached across namespaces when the Gateway allows it. All of that is in the spec rather than in annotations, which is why new features go here.

Reading it

kubectl get gateway,httproute
kubectl describe httproute shop

NAME             CLASS     ADDRESS     PROGRAMMED   AGE
market-gateway   traefik   10.0.0.10   True         1m

PROGRAMMED True means the controller accepted the Gateway and is listening. A route that points at a Gateway that does not exist, or at a Service that does not exist, shows up in describe and in the controller's 404 and 503 answers, exactly like Ingress.