It suprises me how often I see some Dockerfile, Helm, Kubernetes, Ansible etc write .env files to disk in some production-alike environment.

The OS, especially linux - most common for hosting production software - is perfectly capable of setting and providing ENV vars. Almost all common devops and older sysadmin tooling can set ENV vars. Really no need to ever write these to disk.

I think this comes from unaware developers that think a .env file, and runtime logic that reads this file (dotenv libs) in the app are required for this to work. I certainly see this misconception a lot with (junior) developers working on windows.

- you don't need dotenv libraries searching files, parsing them, etc in your apps runtime. Please just leave it to the OS to provide the ENV vars and read those, in your app.

- Yes, also on your development machine. Plenty of tools from direnv to the bazillion "dotenv" runners will do this for you. But even those aren't required, you could just set env vars in .bashrc, /etc/environment (Don't put them there, though) etc.

- Yes, even for windows, plenty of options, even when developers refuse to or cannot use wsl. Various tools, but in the end, just `set foo=bar`.