Repo Layout

hosts/ - Machines/Hardware definitions.
- x1-carbon/ - My laptop
- zfold-5/ - My android Samsung Z Fold 5
- pi4/ - My router, NAS, and other things.
- viture/ - My viture neckband.
modules/ - Modules nixosModules that appear in the flake automatically. Individual files can be imported on imports = [ ... ];
- functions/ - Helper nix functions to accomplish certain tasks. Like (nixGL $program) etc.
secrets/ - age encrypted secrets, made possible by agenix
static/ - static configuration files & folders that are copied to systems.
- ssot/ - Single Source of Truth, stuff like my SSH Keys, etc.
users/ - home-manager configuration per user.
- $username/ - home-manager configuration for a given user
- shared/ - shared home-manager configuration for all users

Building cross compiled NixOS Image for RaspberryPi 4B

When running $nix build .#images.pi, by default nix uses /tmp directory to build the temporary artifacts which can be a problem if you are running on a machine with limited space for /tmp. Compiling kernel requires more than 15GB of space, when your /tmp is a tmpfs you might run into issues. If you have a swap or more memory you can increase the space available to /tmp by running the following command:

sudo mount -o remount,size=32G,nr_inodes=0 /tmp

Using NixGL

NixGL is necessary to set up the GL environment for the user. In order to utilize it as a function in home-manager, you need to write this these your home-manger configuration:

# in flake.nix

outputs = { nixGL, ... }: {
  homeConfigurations = {
    izelnakri = home-manager.lib.homeManagerConfiguration {
      pkgs = x86Pkgs;
      modules = [
        { nixpkgs.overlays = [ nixGL.overlay ]; } # NOTE: This exposes pkgs.nixgl to be used in your modules
        ./users/$USER.nix
      ];
      extraSpecialArgs = { inherit inputs; };
    };
  };
}

# in ./users/izelnakri.nix
{ config, pkgs, inputs, nixosModules, ... }:
let
  nixGL = import ../modules/nix-gl.nix { inherit pkgs; }; # NOTE: loads nixGL function. Example: (nixGL alacritty)
in {
  # either load the package in home.packages or in program.$programName.package:

  home.packages = [
    (nixGL alacritty)
    neovim
  ];

  # or as:

  programs.alacritty = {
    enable = true;
    package = (nixGL alacritty);
  }
}

Tips

Dynamically browse all evaluated options:

nix repl --file '<nixpkgs/nixos>' -I nixos-config=./hosts/izels-pi4/configuration.nix

Run a nix file:

nix eval --file ./entry.nix

Print an expression:

builtins.trace me "return value";

Run a file with an inner module:

echo '{ foo }: foo' > something.nix
echo 'import ./something.nix { foo = "bar"; }' > entry.nix
nix eval --file ./entry.nix

Generate a directory with the specified contents:

$ nix eval --write-to ./out --expr '{ foo = "bar"; subdir.bla = "123"; }'
$ cat ./out/foo
bar
$ cat ./out/subdir/bla
123

Pretty print a nix file:

nix eval --file ./entry.nix | nixfmt
# or
nix eval --file ./entry.nix --json | xq
# retract lambdas and repeated placeholders:
nix eval --file ./entry.nix | sed -r 's/<LAMBDA>/"LOL"/g' | sed -r 's/«repeated»/"REPEATED"/g' | nixfmt
# if the target file is a lambda, you can run it with:
nix eval --expr 'import ./target-file.nix' --impure | sed -r 's/<LAMBDA>/"LOL"/g' | sed -r 's/«repeated»/"REPEATED"/g' | nixfmt

NixGL - home-manager GL support/mess

Add nixGL to registry:

nix registry add nixgl github:guibou/nixGL

nix run --impure nixgl#nixGLDefault -- alacritty

Nix Debugging:

readlink -f `which waybar`
nix-store -q --tree `which hello`
nix-store -q --references `which hello` # runtime dependencies
nix-store -q --referrers `which hello` # all referrers that touches the binary
nix-store -q --tree `which hello` # tree of dependencies
nix-instantiate hello.nix
nix-store -q --references /nix/store/z77vn965a59irqnrrjvbspiyl2rph0jp-hello.drv