On: GNU Guix package definitions for Gov.uk software a...

[cheez]

I think I know the answer but any reason why a maintained docker image isn't good enough?

[majewsky → cheez]

Not GP, but an advantage of a NixOS module is that it has a strongly-typed, explicit API for configuration options, whereas a Docker image would require documentation ala "set those 10 env vars" or "give a YAML config file that looks like this".

[hobofan → majewsky]

And even apart from that, it's really hard to make deterministic build processes for docker images without something like Nix.

[pknopf → hobofan]

I'd argue that you don't need that kind of determinism from docker images. It's nice, but we've been just fine without it.