Gateway

4 minutes read

Exercise 🔗

Prerequisites

This exercise assumes you’re running on a multipass VM with a 3-node Kubernetes cluster. We’ll use NodePort to access the Gateway API controller.

Make sure you have installed the helm client on your host machine.

Install the Gateway API CRDs and Envoy Gateway controller

We’ll use Envoy Gateway, which is one of the most mature Gateway API implementations

helm install eg oci://docker.io/envoyproxy/gateway-helm --version v1.4.2 -n envoy-gateway-system --create-namespace

Wait for Envoy Gateway to be ready.

kubectl wait --timeout=5m -n envoy-gateway-system deployment/envoy-gateway --for=condition=Available

Create the GatewayClass.

cat <<EOF | kubectl apply -f -
apiVersion: gateway.networking.k8s.io/v1
kind: GatewayClass
metadata:
  name: eg
spec:
  controllerName: gateway.envoyproxy.io/gatewayclass-controller
EOF

Create a pod named ghost based on the ghost:4 image and expose it with a ClusterIP service

ghost application listens on port 2368

Create a Gateway resource
Create an HTTPRoute resource to expose the ghost service
Verify you can access the ghost web interface
Create a self-signed TLS certificate for the ghost application
Update the Gateway to support HTTPS with TLS
Verify HTTPS access through the Gateway API
Clean up all resources

Documentation 🔗

https://kubernetes.io/docs/concepts/services-networking/gateway/

https://gateway-api.sigs.k8s.io/

Solution 🔗

Install the Gateway API CRDs and Envoy Gateway controller

Commands provided in instructions.

Create a pod named ghost based on the ghost:4 image and expose it with a ClusterIP service

kubectl run ghost --image=ghost:4 --port 2368 --expose

Create a Gateway resource

cat <<EOF | kubectl apply -f -
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: ghost
spec:
  gatewayClassName: eg
  listeners:
  - name: http
    port: 80
    protocol: HTTP
EOF

The Gateway will create a LoadBalancer service.

$ kubectl get svc -n envoy-gateway-system -l gateway.envoyproxy.io/owning-gateway-name=ghost
NAME                           TYPE           CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
envoy-default-ghost-c7075eaa   LoadBalancer   10.96.231.63   <pending>     80:31283/TCP   2m38s

The following command gets the value of the NodePort assigned to the HTTP (80) port.

HTTP_NODEPORT=$(kubectl get svc -n envoy-gateway-system -l gateway.envoyproxy.io/owning-gateway-name=ghost -o jsonpath='{.items[0].spec.ports[?(@.port==80)].nodePort}')
echo "Gateway HTTP accessible on NodePort: $HTTP_NODEPORT"

As we’ll use the NodePort access, we need to patch the Service so we can reach the Pods from any node.

kubectl -n envoy-gateway-system patch $(kubectl get svc -n envoy-gateway-system -l gateway.envoyproxy.io/owning-gateway-name=ghost -o name) -p '{"spec":{"externalTrafficPolicy":"Cluster"}}'

Create an HTTPRoute resource to expose the ghost service

We create the following HTTPRoute (this is the Gateway API equivalent of an Ingress resource).

cat <<EOF | kubectl apply -f -
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: ghost
spec:
  parentRefs:
  - name: ghost
  rules:
  - matches:
    - path:
        type: PathPrefix
        value: /
    backendRefs:
    - name: ghost
      port: 2368
EOF

Verify you can access the ghost web interface

# Get node IP
NODE_IP=$(kubectl get nodes -o jsonpath='{.items[0].status.addresses[?(@.type=="InternalIP")].address}')

# Get the NodePort (if not already set from previous step)
HTTP_NODEPORT=$(kubectl -n envoy-gateway-system get svc -l gateway.envoyproxy.io/owning-gateway-name=ghost -o jsonpath='{.items[0].spec.ports[?(@.port==80)].nodePort}')

echo "Ghost application accessible at: http://$NODE_IP:$HTTP_NODEPORT"

# Test HTTP access
curl http://$NODE_IP:$HTTP_NODEPORT/

The ghost web interface should be accessible at http://$NODE_IP:$HTTP_NODEPORT

Create a self-signed TLS certificate for the ghost application

# Generate private key and certificate
openssl req -x509 -nodes -days 365 -newkey rsa:2048 \
  -keyout ghost-tls.key \
  -out ghost-tls.crt \
  -subj "/CN=ghost.local"

# Create Kubernetes Secret
kubectl create secret tls ghost-tls-secret \
  --cert=ghost-tls.crt \
  --key=ghost-tls.key

Update the Gateway to support HTTPS with TLS

# Update Gateway to include HTTPS listener
cat <<EOF | kubectl apply -f -
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: ghost
spec:
  gatewayClassName: eg
  listeners:
  - name: http
    port: 80
    protocol: HTTP
  - name: https
    port: 443
    protocol: HTTPS
    tls:
      mode: Terminate
      certificateRefs:
      - name: ghost-tls-secret
EOF

As we’ll use the NodePort access, we need to patch the Service so we can reach the Pods from any node.

kubectl -n envoy-gateway-system patch $(kubectl get svc -n envoy-gateway-system -l gateway.envoyproxy.io/owning-gateway-name=ghost -o name) -p '{"spec":{"externalTrafficPolicy":"Cluster"}}'

Verify HTTPS access through the Gateway API

# Get the NodePort assigned to HTTPS (port 443)
HTTPS_NODEPORT=$(kubectl -n envoy-gateway-system get svc -l gateway.envoyproxy.io/owning-gateway-name=ghost -o jsonpath='{.items[0].spec.ports[?(@.port==443)].nodePort}')
echo "Gateway HTTPS accessible on NodePort: $HTTPS_NODEPORT"

# Test HTTPS access (with self-signed cert)
curl -k https://$NODE_IP:$HTTPS_NODEPORT/

Clean up all resources, and remove envoy gateway

kubectl delete httproute ghost
kubectl delete gateway ghost
kubectl delete secret ghost-tls-secret
kubectl delete pod ghost
kubectl delete service ghost
rm ghost-tls.key ghost-tls.crt
helm uninstall eg -n envoy-gateway-system