这么配置：

    upstream gitlab {
        server <DOMAIN>:80;
    }

    server {
        listen 8088;
        location / {
                client_max_body_size 50m;
                proxy_redirect off;
                proxy_set_header Host $host:$server_port;
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                # 一定注意下一行最后那个/ 可以代理全站，没有/就会出现问题
                proxy_pass http://gitlab/;
                index index.html index.htm;
            }
          access_log /var/log/gitlab-access.log;
        }