Nginx默认不传递主机头，您必须告诉它:

Nginx doesn't pass the host header by default, you have to tell it to:

 location @unicorn {
    proxy_set_header Host $http_host; 
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header Client-IP $remote_addr;
    proxy_set_header X-Forwarded-For $remote_addr;
    proxy_pass http://unicorn;
  }

否则，请求发送到的主机将丢失.

Otherwise which host the request was sent to gets lost.