`sudo gitlab-ctl deploy-page up`. When a user goes to your GitLab URL, they
will be shown an arbitrary `Deploy in progress` page.
To remove the page, you simply run `sudo gitlab-ctl deploy-page down`.
To remove the page, you simply run `sudo gitlab-ctl deploy-page down`.
You can also check the status of the deploy page with `sudo gitlab-ctl deploy-page status`.
As a side note, if you would like to restrict logging into GitLab and restrict
changes to projects, you can [set projects as read-only](https://docs.gitlab.com/ee/administration/troubleshooting/gitlab_rails_cheat_sheet.html#make-a-project-read-only-can-only-be-done-in-the-console)