What is the right way to deal with SECRET_KEY when pushing to github?

Question

Django

There is a project with normal mysql. They write that you need to create a secret_settings.py file and put SECRET_KEY there and then add it to .gitignore, but as I understand it, this is more about closed repositories. I don’t quite understand how an employer can kick my project completely if they can’t just run it without a key. I also know that you can do this through docker and environment variables. The option about environment variables is interesting, tell me who uploads public repositories?