https://docs.gitlab.com/omnibus/settings/nginx.html#vhost-server-blocknginx报502可能原因是sock文件没有访问权限
将www-data用户添加进gitlab-www组
usermod -aG gitlab-www www-data
注意nginx需要restart，只是reload依然不能访问
https://stackoverflow.com/questions/35327882/what-permissions-does-nginx-need-for-the-gitlab-workhorse-socket