网站中图片过大无法正常显示，通常显示一半，就提示502错误了，Nginx 错误日志代理提示：

2021/05/19 16:28:35 [crit] 10976#0: *13 open() "/nginx_dir/proxy_temp/2/00/0000000002" failed (13: Permission denied) while reading upstream, client: 200.130.237.38, server: test.com, request: "GET /uploads/images/20210220/48a18881fa3b45781b512f2376c9bef8.gif HTTP/1.1", upstream: "http://127.0.0.1:3001/uploads/images/20210220/48a18881fa3b45781b512f2376c9bef8.gif", host: "www.test.com", referrer: "https://www.test.com/cat/5"

当前nginx的用户是谁

ps aux | grep "nginx: worker process"

然后查看

ll /nginx_dir/proxy_temp

发现一切正常，尝试调整缓存大小限制，无效。

放弃使用node提供静态文件功能，使用nginx 直接托管上传后的静态文件，nginx配置文件中加入：

location /uploads {
  alias /www/test_com/static/uploads;
}