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.
1. Use kubectl to connect to the Container Service for Kubernetes (ACK) cluster based on the information in the kubeconfig file, and run the following command to enable bash for the sleep service:
```
kubectl exec -it deploy/sleep -- sh
```
2. Run the following command to send a request to the HTTPBin service:
```
curl -I httpbin:8000
```
  Expected output:
```
HTTP/1.1 200 OK
server: istio-envoy
date: Thu, 10 Aug 2023 09:32:09 GMT
content-type: text/html; charset=utf-8
content-length: 9593
access-control-allow-origin: *
access-control-allow-credentials: true
x-envoy-upstream-service-time: 2
```
Use the following content to create a virtual 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 configurations take effect.
1. Use kubectl to connect to the ACK cluster based on the information in the kubeconfig file, and run the following command to enable bash for the sleep service:
```
kubectl exec -it 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
```