How to rewrite the Authority and Host headers of a request - Alibaba Cloud Service Mesh

Service Mesh (ASM) allows a service mesh proxy to rewrite the Authority and Host headers of an HTTP request before the request is sent to a specific host. If a request needs to be redirected to another service using a virtual service, you must configure a rule to rewrite the Host and Authority headers so that the destination service accepts the request. This topic describes how to configure a rule to rewrite the Host and Authority headers of a request.

Prerequisites

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

Procedure

Configure a virtual service for the nginx service to forward requests to the httpbin service. Also, configure a rule to rewrite the Host and Authority headers to httpbin:8000.
1. Log on to the ASM console. In the left-side navigation pane, choose Service Mesh > Mesh Management.
2. On the Mesh Management page, click the name of the ASM instance. In the left-side navigation pane, choose Traffic Management Center > VirtualService. On the page that appears, click Create.
3. On the Create page, configure the following parameters, and click Preview. Confirm that the YAML content is correct, click Submit, and then click Create.
  Expand to view the YAML file
```
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: nginx
  namespace: default
spec:
  hosts:
    - nginx.default.svc.cluster.local
  http:
    - rewrite:
        authority: 'httpbin:8000'
      route:
        - destination:
            host: httpbin.default.svc.cluster.local
```
Run the following command to check whether the header rewriting configuration takes effect:
```
kubectl exec -it deploy/sleep -- curl nginx:8000/headers
```
Expected output:
```
{
  "headers": {
    "Accept": "*/*", 
    "Host": "httpbin:8000", 
    "User-Agent": "curl/8.1.2"
  }
}
```
The output shows that requests from the sleep container to the /headers path of the nginx service are forwarded to the /headers path of the httpbin service. The request is sent to http://httpbin:8000/headers. This path returns the headers from the request that it received. You can see that the Host header was rewritten to httpbin:8000.
Important
In Ambient Mesh mode, to rewrite the Authority and Host headers of requests to forward the requests destined for service 1 to service 2, a waypoint proxy must not be deployed for service 2.