Direct responses

Use the directResponse API to directly respond to incoming requests without forwarding them to services. Instead, you return a pre-defined body and HTTP status code to the client.

About direct responses

When you configure a direct response, the gateway proxy intercepts requests to specific routes and directly sends back a predefined response. Common use cases include:

• Static responses: You might have endpoints for which sending back static responses is sufficient.
• Health checks: You might configure health checks for the gateway.
• Redirects: You might redirect users to new locations, such as when an endpoint is now available at a different address.
• Test responses: You can simulate responses from backend services without forwarding the request to the actual service.

Limitation

You cannot configure multiple direct response resources on the same route. If you configure multiple direct responses, only the oldest is applied.

Schema validation

The following rule is applied during schema validation:

• The status field can define a valid HTTP status code in the 200-599 range.

Before you begin

1. Set up an agentgateway proxy.
2. Install the httpbin sample app.

Set up direct responses

1. Create an HTTPRoute resource that routes traffic with the / path.

   kubectl apply -f- <<EOF
   apiVersion: gateway.networking.k8s.io/v1
   kind: HTTPRoute
   metadata:
     name: direct-response
     namespace: agentgateway-system
   spec:
     parentRefs:
       - name: agentgateway-proxy
         namespace: agentgateway-system
     rules:
       - matches:
           - path:
               type: PathPrefix
               value: /
   EOF

2. Create an AgentgatewayPolicy resource with a directResponse configuration. The policy is applied on the HTTPRoute that you created earlier and returns a 200 HTTP response code with a custom message body.

   kubectl apply -f- <<EOF
   apiVersion: agentgateway.dev/v1alpha1
   kind: AgentgatewayPolicy
   metadata:
     name: direct-response
     namespace: agentgateway-system
   spec:
     targetRefs:
       - group: gateway.networking.k8s.io
         kind: HTTPRoute
         name: direct-response
     traffic:
       directResponse:
         status: 200
         body: "Status: Healthy"
   EOF

3. Send a request along the /status/404 path of the httpbin app. Typically, this path returns a 404 HTTP response code. However, because you apply a direct response to this route, the request returns a 200 HTTP response code with a custom message instead as defined in your policy. Verify that you see the 200 HTTP response code with your custom message.
   

   Cloud Provider LoadBalancerPort-forward for local testing

   curl -vi http://$INGRESS_GW_ADDRESS:80/status/404

   curl -vi localhost:8080/status/404

   Example output:

   ...
   < HTTP/1.1 200 OK
   HTTP/1.1 200 OK
   < content-length: 15
   content-length: 15
   < 
   
   * Connection #0 to host localhost left intact
   Status: Healthy% 

Cleanup

You can remove the resources that you created in this guide. Run the following commands.

kubectl delete AgentgatewayPolicy health-response -n agentgateway-system
kubectl delete httproute direct-response -n agentgateway-system