nix flakes environment

.envrc

use_flake

README.md

$ nix build
$ docker load <result
Loaded image: refb/devenv:latest

$ docker run -ti refb/devenv sassc
Usage: sassc [options] [INPUT] [OUTPUT]

The cool thing is that I can use the same to just get into a shell with the same environment without docker: $ nix shell

Or automatically by entering the project directory by setting up direnv in my shell:

.envrc (for use with direnv )

use_flake

and then cd into the directory.

You can pin version too. Actually there is a flake.lock being created and you can use git to version the flake origins/custom pkgs etc. Did not went that far in this example.

flake.nix

{
  description = "A basic flake with a shell";
  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
  inputs.flake-utils.url = "github:numtide/flake-utils";

  outputs = { self, nixpkgs, flake-utils }:
    flake-utils.lib.eachDefaultSystem (system: let
      pkgs = nixpkgs.legacyPackages.${system};
      contents = with pkgs; [
        bashInteractive
        protobuf
        sassc
      ];
      shell = pkgs.mkShell {
        buildInputs = contents;
      };
      docker = pkgs.dockerTools.buildImage {
         name = "refb/devenv";
         tag = "latest";
         contents = contents;
         config = {
           Env = with pkgs; [ "PATH=${protobuf}/bin/:${sassc}/bin/" ];
         };
      };
    in rec {
      defaultPackage = docker;
      devShell = shell;
    });
}