Shellify

Want to quicky get something to build and to have it reproducable and sharable? With nix it is easy to quickly add dependencies to get something to build. It's also easy to work quickly and iteratively. With this tool, once you're done you can save a shell.nix so that you and anybody else can quickly and instantly rebuild with an identical environment with all the same dependencies. Just swap out nix-shell or nix for nix-shellify to create the necessary shell.nix in the local directory. It makes saving a basic working shell.nix almost instant. Take a look at the short examples below to see the workflow.

Prerequisites

This utility assumes nix is installed.

Example usage without flakes

I want to run a program called foo. When I run ./foo it complains I don't have python. So I run nix-shell -p python and try running ./foo again.

Now it complains I don't have asciidoc so I come out of the shell and edit the last command to add asciidoc by running nix-shell -p python asciidoc. Now it works.

I exit my shell and change nix-shell -p python asciidoc to nix-shellify -p python asciidoc. It then creates a shell.nix which I keep next to foo. It looks like this:

{ pkgs ? import <nixpkgs> {} }:

pkgs.mkShell {

  buildInputs = [
    pkgs.asciidoc
    pkgs.python
  ];

}

Now I can just type nix-shell and I have what I need to run foo. I can share and everybody else can run foo too without the same search. They also don't need to run it in a conatainer or VM or to maintain depenencies on their system themself.

Example usage with flakes

I want to run something called foo. When I run ./foo it complains I don't have python. So I run nixshell nixpkgs#python and try running ./foo again.

Now it complains I didn't have asciidoc so I come out of the shell and edit the last command to add asciideoc by running nix shell nixpkgs#python nixpkgs#asciidoc. Now it works.

I exit my shell and change nix shell nixpkgs#python nixpkgs#asciidoc to nix-shellify shell nixpkgs#python nixpkgs#asciidoc. I do this by quickly extending nix to nix-shellify using tab completion. It then creates a flake.nix and shell.nix which I commit in git next to foo. Now I can just type nix develop and I have what I need to run foo. I can share and everybody else can quickly run foo too with the same environment. I can also go on to modify my nix files e.g. to run as an app or run an initialisation command when starting the shell.