nginx return 调试变量

location / {
        set $upstream_name "10.x.x.x:8711";
        more_set_headers 'Content-Type: text/html; charset=utf-8';
        return 200 "系统已经迁移至 xz.test.com，相关问题请咨询xxx";
        proxy_pass  http://$upstream_name;
    }

　　

location ^~ /pic {
          default_type text/html ;
          return 200  'test test test ';
        }

　　

 location ^~ /pic {
          default_type application/json ;
          return 200  '{"name":"nanjing_wuxu","result":"success"}';
        }

　　

 location ^~ /pic {
          return http://192.168.1.19:8080/aa.jpg;
        }

　　

ocation = /test {
         return 403 ;
        }