Prohibit gitlab server search engine indexing

How do I completely prohibit a private gitlab server search engine indexing? I want it to be a blackbox to search engines. Not one bit indexed.

Is there is a definite way to guarantee that?

It was extremely annoying to find that all indexing questions about gitlab were asking for the ability to have it indexed! It makes you feel like you are the only entity in the world running a private gitlab server with private code!

Any help is very much appreciated.

Are you asking about indexing by search engines like Google? IOW, to prevent crawling anything in your GitLab instance?