How to configure a direct response - Alibaba Cloud Service Mesh

For a matched request, a service mesh proxy can directly return an HTTP response to the client according to the configured HTTP rule, instead of forwarding the request to the destination service. This topic describes how to configure a direct response.

Prerequisites

The preparations are completed, and the HTTPBin and sleep services are deployed. For more information, see Preparations.

Procedure

Check whether the service configurations take effect.

In the kubeconfig environment for the ACK cluster, run the following command to start a bash session in the sleep environment.
```
kubectl exec -it deploy/sleep -- sh
```

Run the following command to send a request to the HTTPBin service:

curl -I httpbin:8000

Expected output:

HTTP/1.1 200 OK
Server: gunicorn/19.9.0
Date: Mon, 28 Aug 2023 06:15:30 GMT
Connection: keep-alive
Content-Type: text/html; charset=utf-8
Content-Length: 9593
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true

Use the following content to configure a traffic rule for the HTTPBin service and add a direct response configuration. For more information, see Manage virtual services.

apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: httpbin-vs
  namespace: default
spec:
  hosts:
    - httpbin.default.svc.cluster.local
  http:
    - directResponse:
        body:
          string: unknown error
        status: 503

Check whether the direct response configuration takes effect.
1. In the kubeconfig environment for the ACK cluster, run the following command to start a bash session in the sleep environment.
```
kubectl exec -it -n default deploy/sleep -- sh
```
2. Run the following command to send a request to the HTTPBin service:
```
curl -I httpbin:8000
```
  Expected output:
```
HTTP/1.1 503 Service Unavailable
content-length: 13
content-type: text/plain
date: Thu, 10 Aug 2023 09:33:52 GMT
server: istio-envoy
```
3. Run the following command to send a request to the HTTPBin service:
```
curl httpbin:8000
```
  Expected output:
```
unknown error
```
  The output results indicate that the direct response configuration takes effect.