Would it make it much easier? If you really need env var support, you can just wrap this, I suppose. But more conveniently, you can also mount (and load from a config map in the context of kubernetes).
Yes, I think that env vars are superior to a file or CLI args. One advantage is that you can pass secrets without persisting in a file or making them visible to other processes through CLI args.
Env vars are visible in /proc/PID/environ, though? That said, the mode on environ seems to be 600 on my system, so only processes with the same UID can see them.
Does that mean you're restarting your nodes after every change? It'll work, but mightn't it be a bit tricky if lots of people start creating tenants?
Edit: actually, based on the use case cited in the readme, this would be fine. I was thinking more of a website like GitHub that lets people sign up and create tenants.