https://xenby.com/b/131-%E6%8E%A8%E8%96%A6-gitlab%E5%AE%89%E8%A3%9D%E8%88%87%E5%9F%BA%E6%9C%AC%E8%A8%AD%E5%AE%9A%E6%95%99%E5%AD%B8
https://gitlab.com/gitlab-org/gitlab-ce/#installation
sudo nano /etc/gitlab/gitlab.rb
可以在裡面找到external_url
sudo gitlab-ctl reconfigure