I'd recommend giving Java system properties a try if you haven't - they're very idiomatic and can be altered at runtime (and from lein config e.g. a specific file) If going the env route, I'd recommend more something more modern like https://github.com/juxt/aero where env is just one of the options. e.g. use the env in production, use this fixed value in dev, etc

Thanks for the suggestions! Since this is a legacy customer product that already uses lein-dotenv (and duct for that matter) I’m not sure I’ll be able to introduce sth like aero.