Each time someone talks about the 12 Factor Application a weird feeling overcomes me … Because I like the concept, but it feels awkward. It feels as if someone with 0 operational experience wrote it. And this devil is in a really small detail.
And that is Part III. Config … For me (and a lot of other folks I’ve talked to about this topic), using environment variables (as in real environment variables) are just one of the worst ideas ever. Environment variables are typically set manually, or from a script that is being executed and there’s little or trace to see fast how a specific config is set.