我正在使用NGINX服务器作为反向代理。 NGINX服务器接受来自外部客户端的请求（HTTP或HTTPS无关紧要），并将此请求传递给后端服务器。后端服务器向客户端返回“ a” URL，该客户端将具有另一个URL，应使用该URL进行后续的API调用。我希望此返回的URL具有NGIX主机和端口号，而不是后端服务主机和端口号，以便永远不会暴露我的后端服务器详细信息。例如。

1) Client request: 
http://nginx_server:8080

2) Nginx receives this and passes it to the backend running with some functionality at 
http://backend_server:8090

3) The backend server receives this request and passes another URL to the client http://backend_server:8090/allok.

4) The client uses this URL and makes another subsequent API calls.

我想要的是在响应的第4步中，将“ backend_server：port”替换为初始请求中的nginx服务器和端口。对于例如

http://nginx_server:8080/allok

但是，响应返回为

http://backend_server:8090/allok

我的nginx.conf

http {
    server {
        listen       8080;     --> Client request port
        server_name  localhost;

        location / {         
            proxy_pass http://localhost:8090;   ---> Backend server port. The backend 
                                                     service and NGINX will always be on the same 
                                                     machine
            proxy_redirect http://localhost:8090 http://localhost:8080; --> Not sure if this is 
                                               correct. Doesn't seem to do what I want to achieve
           # proxy_set_header Host $host;
        }
  }
}

预先感谢