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Kubernetes Gateway API

Kuma supports configuring Built-in Gateway using Kubernetes Gateway API.

Installation

Gateway API support is an experimental feature that has to be explicitly enabled.

Install Gateway API CRDs

The Gateway API CRDs are not yet available by default in Kubernetes. You must first install them.
Enable Built-in Gateway and Gateway API support

Gateway API can only be used when Kuma built-in Gateway is enabled.

When Kuma is installed with kumactl, use --experimental-meshgateway and --experimental-gatewayapi.

When Kuma is installed with HELM, use experimental.meshGateway=true value and experimental.gatewayAPI=true.

Usage

Setup counter demo application

kumactl install demo | kubectl apply -f -

Add GatewayClass and Gateway

The Gateway resource represents the proxy instance that handles traffic for a set of Gateway API routes, and a GatewayClass describes characteristics shared by all Gateways of a given type.

echo "apiVersion: gateway.networking.k8s.io/v1alpha2
kind: GatewayClass
metadata:
  name: kuma
spec:
  controllerName: gateways.kuma.io/controller
" | kubectl apply -f -

echo "apiVersion: gateway.networking.k8s.io/v1alpha2
kind: Gateway
metadata:
  name: kuma
  namespace: kuma-demo
spec:
  gatewayClassName: kuma
  listeners:
  - name: proxy
    port: 8080
    protocol: HTTP
" | kubectl apply -f -

When Gateway resource is applied, Kuma automatically creates an instance of a built-in Gateway with a corresponding Service.

kubectl get pods -n kuma-demo
NAME                          READY   STATUS    RESTARTS   AGE
redis-59c9d56fc-6gcbc         2/2     Running   0          2m8s
demo-app-5845d6447b-v7npw     2/2     Running   0          2m8s
kuma-4j6wr-58998b5576-25wl6   1/1     Running   0          30s
   
kubectl get svc -n kuma-demo
NAME         TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
redis        ClusterIP      10.43.223.223   <none>        6379/TCP         3m27s
demo-app     ClusterIP      10.43.216.203   <none>        5000/TCP         3m27s
kuma-pfh4s   LoadBalancer   10.43.122.93    172.20.0.3    8080:30627/TCP   87s

Gateway can now be accessed using 172.20.0.3:8080 address.

Add an HTTPRoute

HTTPRoute resources contains a set of matching criteria for HTTP requests and upstream Services to route those requests to.

echo "apiVersion: gateway.networking.k8s.io/v1alpha2
kind: HTTPRoute
metadata:
  name: echo
  namespace: kuma-demo
spec:
  parentRefs:
  - group: gateway.networking.k8s.io
    kind: Gateway
    name: kuma
    namespace: kuma-demo
  rules:
  - backendRefs:
    - group: ''
      kind: Service
      name: demo-app
      port: 5000
      weight: 1
    matches:
    - path:
        type: PathPrefix
        value: /
" | kubectl apply -f -

After creating an HTTPRoute, accessing / forwards a request to the demo app:

curl 172.20.0.3:8080/ -i

HTTP/1.1 200 OK
x-powered-by: Express
accept-ranges: bytes
cache-control: public, max-age=0
last-modified: Tue, 20 Oct 2020 17:16:41 GMT
etag: W/"2b91-175470350a8"
content-type: text/html; charset=UTF-8
content-length: 11153
date: Fri, 18 Mar 2022 11:33:29 GMT
x-envoy-upstream-service-time: 2
server: Kuma Gateway
   
<html>
<head>
...

TLS Termination

Gateway API supports TLS termination by using standard kubernetes.io/tls Secrets.

Here is an example

apiVersion: v1
kind: Secret
metadata:
  name: secret-tls
  namespace: kuma-demo
type: kubernetes.io/tls
data:
  tls.crt: "MIIEOzCCAyO..." # redacted
  tls.key: "MIIEowIBAAKC..." # redacted

apiVersion: gateway.networking.k8s.io/v1alpha2
kind: Gateway
metadata:
  name: kuma
  namespace: kuma-demo
spec:
  gatewayClassName: kuma
  listeners:
  - name: proxy
    port: 8080
    hostname: test.kuma.io
    protocol: HTTPS
    tls:
      certificateRefs:
      - name: secret-tls

Under the hood, Kuma CP copies the Secret to kuma-system namespace and converts it to Kuma Secret. It tracks all the changes to the secret and deletes it if the original secret is deleted.

Multizone

Gateway API is not supported with multizone deployments, use Mesh Gateway CRDs instead.

How does it work

When the feature is enabled, Kubernetes Gateway API CRDs are automatically converted to Kuma Mesh Gateway CRDs. This is the reason why in the GUI we will see Kuma Mesh Gateway and not Kubernetes Gateway API resources.

When using Kubernetes Gateway API CRDs, it is a source of truth, so do not edit Kuma Mesh Gateway CRDs directly.

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