NixOS: installing services from npm, possibly w/ overlays?

Hi there, I’m a NixOS newb so my apologies if I’ve missed something obvious, but I’ve been having trouble figuring out how to run packages from npm on NixOS.

I’ve run into this with a few packages, most recently thelounge (a web IRC client) and Ghost, a blogging platform. Happily thelounge now has an entry in nixpkgs, but the PR for Ghost seemed to run into a dead end. Basically: I have no idea how to go about running these things on my own nixos machine, short of installing them into my home directory and launching them from a tmux session to keep them alive. Which, obviously, defeats the whole point of running NixOS :slight_smile:

I have two questions: first, is there any good information on how to add a package like Ghost to nixpkgs? I haven’t been able to find a complete & coherent guide to using any of the 5 “npm to nix” tools I’ve found (node2nix, npm2nix, yarn2nix, nixfromnpm, npm4nix) that would help me to build a PR to nixpkgs to add something like Ghost. If I did so, would it be rejected on the same grounds that the previous PR was rejected, i.e. too many added lines?

Secondly, what’s the best way to go about installing this sort of thing (npm or otherwise, but npm seems especially tricky) locally, without having to PR it to nixpkgs? I hear people talking about ‘overlays’ sometimes but I haven’t found a guide to making and maintaining one.

Thanks in advance, trying to learn! :bowing_man: