Introduction

In the First Nix Post I ended with three questions. I have solved those questions and wanted to post the answers here.

How to make a package available on aarch64-darwin

This turned out to be extremely simple. As a easy test case I wanted to make flameshot available on my macbook. I did so with this pull request.

It turned out I just needed to add platforms.darwin to the listed platforms.

     homepage = "https://github.com/flameshot-org/flameshot";
     maintainers = with maintainers; [ scode oxalica ];
     license = licenses.gpl3Plus;
-    platforms = platforms.linux;
+    platforms = platforms.linux ++ platforms.darwin;

How do I package a project for nix from scratch

This is a bit more nuanced as is extremely dependent on the type of project. After packaging a python, rust, c++, and go application. I think the best advice is to find a similar project already packaged for nix and use that as a starting point.

What are flakes and why should I use them

I won’t be able to state this better than this fantastic series of posts, but my main take aways were:

• Fully reproducable packages due to a flake.lock file
• MUCH faster development shells with direnv due to caching. I have moved most of my shell.nix files to a flake.nix. Below are some samples

Overall I’m very much enjoying using both NixOs and nix-shells for development environments.

Hugo Environment

{
description = "Hugo environment";

  outputs = { self, nixpkgs, ... }:
    let

      # Generate a user-friendly version number.
      version = builtins.substring 0 8 self.lastModifiedDate;

      # System types to support.
      supportedSystems =
        [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ];

      # Helper function to generate an attrset '{ x86_64-linux = f "x86_64-linux"; ... }'.
      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;

      # Nixpkgs instantiated for supported system types.
      nixpkgsFor = forAllSystems (system: import nixpkgs { inherit system; });

    in {

      devShells = forAllSystems (system:
        let pkgs = nixpkgsFor.${system};
        in {
          default = pkgs.mkShell {
            buildInputs = with pkgs; [
              hugo
];
          };
      });

      devShell = forAllSystems (system: self.devShells.${system}.default);
    };
}

Golang Environment

{
description = "golang dev environment";

  outputs = { self, nixpkgs, ... }:
    let

      # Generate a user-friendly version number.
      version = builtins.substring 0 8 self.lastModifiedDate;

      # System types to support.
      supportedSystems =
        [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ];

      # Helper function to generate an attrset '{ x86_64-linux = f "x86_64-linux"; ... }'.
      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;

      # Nixpkgs instantiated for supported system types.
      nixpkgsFor = forAllSystems (system: import nixpkgs { inherit system; });

    in {

      devShells = forAllSystems (system:
        let pkgs = nixpkgsFor.${system};
        in {
          default = pkgs.mkShell {
            buildInputs = with pkgs; [
              go
              gotools
              gopls
              go-outline
              gocode
              gopkgs
              gocode-gomod
              godef
              golint
];
          };
      });

      devShell = forAllSystems (system: self.devShells.${system}.default);
    };
}

Rust Environment

{
description = "rust dev environment";

  outputs = { self, nixpkgs, ... }:
    let

      # Generate a user-friendly version number.
      version = builtins.substring 0 8 self.lastModifiedDate;

      # System types to support.
      supportedSystems =
        [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ];

      # Helper function to generate an attrset '{ x86_64-linux = f "x86_64-linux"; ... }'.
      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;

      # Nixpkgs instantiated for supported system types.
      nixpkgsFor = forAllSystems (system: import nixpkgs { inherit system; });

    in {

      devShells = forAllSystems (system:
        let pkgs = nixpkgsFor.${system};
        in {
          default = pkgs.mkShell {
            buildInputs = with pkgs; [
              rustc
              cargo
              gcc
              rustfmt
              clippy
            ];
          };
      });

      devShell = forAllSystems (system: self.devShells.${system}.default);
    };
}