Enable a health check plugin on your gateway proxy to respond with common HTTP codes.

Gloo Gateway includes an HTTP health checking plug-in that you can enable for a gateway proxy listener. This plug-in responds to health check requests directly with either a 200 OK or 503 Service Unavailable message, depending on the current draining state of Envoy.

Before you begin

  1. Follow the Get started guide to install Gloo Gateway.

  2. Follow the Sample app guide to create a gateway proxy with an HTTP listener and deploy the httpbin sample app.

  3. Get the external address of the gateway and save it in an environment variable.

      export INGRESS_GW_ADDRESS=$(kubectl get svc -n gloo-system http -o jsonpath="{.status.loadBalancer.ingress[0]['hostname','ip']}")
echo $INGRESS_GW_ADDRESS  
  
      kubectl port-forward deployment/http -n gloo-system 8080:8080

Configure a health check on a gateway

  1. Create an HTTPListenerPolicy resource to configure a health check path for the HTTP or HTTPS listener on the gateway. You can define any path, such as /check/healthz.

      kubectl apply -f- <<EOF
apiVersion: gateway.kgateway.dev/v1alpha1
kind: HTTPListenerPolicy
metadata:
  name: healthcheck
  namespace: gloo-system
spec:
  targetRefs:
  - group: gateway.networking.k8s.io
    kind: Gateway
    name: http
  healthCheck:
    path: <path>
EOF

  2. To test the health check, drain the Envoy connections by sending an HTTP POST request to the /healthcheck/fail endpoint of the Envoy admin port.

    1. Port-forward the http deployment on port 19000.
        kubectl port-forward deploy/http -n gloo-system 19000 &
    2. Send an HTTP POST request to the /healthcheck/fail endpoint. This causes Envoy connections to begin draining.
        curl -X POST 127.0.0.1:19000/healthcheck/fail

  3. Send a request to the health check path. Because Envoy is in a draining state, the 503 Service Unavailable message is returned.

      curl -i $INGRESS_GW_ADDRESS:8080/<path>
  
      curl -i localhost:8080/<path>

    Example output:

      HTTP/1.1 503 Service Unavailable
x-envoy-upstream-healthchecked-cluster: http.gloo-system
x-envoy-immediate-health-check-fail: true
date: Wed, 16 Jul 2025 16:35:12 GMT
server: envoy
connection: close
content-length: 0

  4. After you finish testing, resume Envoy connections by sending an HTTP POST request to the /healthcheck/ok endpoint of the Envoy admin port.

      curl -X POST 127.0.0.1:19000/healthcheck/ok

  5. Send another request to the health check path. Because Envoy is operating normally, the 200 OK message is returned.

      curl -i $INGRESS_GW_ADDRESS:8080/<path>
  
      curl -i localhost:8080/<path>

    Example output:

      HTTP/1.1 200 OK
x-envoy-upstream-healthchecked-cluster: http.gloo-system
date: Wed, 16 Jul 2025 16:37:13 GMT
server: envoy
content-length: 0

  6. Stop port-forwarding the http deployment.

      lsof -ti:19000 | xargs kill -9

Cleanup

You can remove the resources that you created in this guide.
  kubectl delete HTTPListenerPolicy healthcheck -n gloo-system