Kubernetes Gateway API

This task describes how to configure Istio to expose a service outside of the service mesh cluster, using the Kubernetes Gateway API. These APIs are an actively developed evolution of the Kubernetes Service and Ingress APIs.

Setup

1. Install the Gateway API CRDs:

   $ kubectl kustomize "github.com/kubernetes-sigs/gateway-api/config/crd?ref=v0.3.0" | kubectl apply -f -
   

2. Install Istio:

   $ istioctl install
   

3. Follow the instructions in the Determining the ingress IP and ports sections of the Ingress Gateways task in order to retrieve the external IP address of your ingress gateway.

Configuring a Gateway

See the Gateway API documentation for information about the APIs.

1. Deploy a test application:

   Zip

   $ kubectl apply -f @samples/httpbin/httpbin.yaml@
   

2. Deploy the Gateway API configuration:

   $ kubectl apply -f - <<EOF
   apiVersion: networking.x-k8s.io/v1alpha1
   kind: GatewayClass
   metadata:
     name: istio
   spec:
     controller: istio.io/gateway-controller
   ---
   apiVersion: networking.x-k8s.io/v1alpha1
   kind: Gateway
   metadata:
     name: gateway
     namespace: istio-system
   spec:
     gatewayClassName: istio
     listeners:
     - hostname: "*"
       port: 80
       protocol: HTTP
       routes:
         namespaces:
           from: All
         selector:
           matchLabels:
             selected: "yes"
         kind: HTTPRoute
   ---
   apiVersion: networking.x-k8s.io/v1alpha1
   kind: HTTPRoute
   metadata:
     name: http
     namespace: default
     labels:
       selected: "yes"
   spec:
     gateways:
       allow: All
     hostnames: ["httpbin.example.com"]
     rules:
     - matches:
       - path:
           type: Prefix
           value: /get
       filters:
       - type: RequestHeaderModifier
         requestHeaderModifier:
           add:
             my-added-header: added-value
       forwardTo:
       - serviceName: httpbin
         port: 8000
   EOF
   

3. Access the httpbin service using curl:

   $ curl -s -I -HHost:httpbin.example.com "http://$INGRESS_HOST:$INGRESS_PORT/get"
   HTTP/1.1 200 OK
   server: istio-envoy
   ...
   

   Note the use of the -H flag to set the Host HTTP header to “httpbin.example.com”. This is needed because the HTTPRoute is configured to handle “httpbin.example.com”, but in your test environment you have no DNS binding for that host and are simply sending your request to the ingress IP.

4. Access any other URL that has not been explicitly exposed. You should see an HTTP 404 error:

   $ curl -s -I -HHost:httpbin.example.com "http://$INGRESS_HOST:$INGRESS_PORT/headers"
   HTTP/1.1 404 Not Found
   ...