If you don't mind, I'll keep doing the relatively sane thing: using env variable at the startup of my applications (and, as much as possible, never anywhere els

If you don't mind, I'll keep doing the relatively sane thing: using env variable at the startup of my applications (and, as much as possible, never anywhere else), among other configuration sources (like text files), to create a struct / object / dict / whatever that represents the configuration, and that the rest of my code uses. If you see someone using `os.env["xxx"]` as an escape hatch for a mutable global variable, then, yes, it's probably not a good idea. But it's not configuration anymore, it's runtime state. (Although I suppose no one is going to hit HN front page by writing an article titled "Don't use global mutable state", except to make game programmers giggle ?)