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#+title: Useful Nix bits

This pages houses a few configuration snippets that might be useful if you are new to the nix ecosystem. It will be infrequently updated as I come across things that I deem to be interesting to such a reader.

* Importing a NixOS module that is not in nixpkgs

This requires changes in multiple locations. As an example we will use an early version of the mautrix-signal module by Niklas Korz.

1) Add the module source to flake.nix:

   #+begin_src nix flake.nix
     {
       inputs = {
         [...]
           # provides expressions for mautrix-signal
           nixpkgs-mautrix-signal ={
           url = github:niklaskorz/nixpkgs/nixos-23.11-mautrix-signal;
         };
         [...]
       };

       outputs = inputs@{
         self,
           [...]
             nixpkgs-mautrix-signal,
           [...]
       }: let
         [...]
           pkgsmautrix = import nixpkgs-mautrix-signal { inherit system;
                                                         config.allowUnfree = true;
                                                       };
         [...]
       in {
         nixosConfigurations = {
           matrix = nixpkgs.lib.nixosSystem {
             pkgs = pkgsmautrix;
             # this is to import a service module that is not on nixpkgs
             # this way avoids infinite recursion errors
             specialArgs.unstable = nixpkgs-mautrix-signal;
             modules = [
               [...]
             ];
           };
         };
       }
     }

   #+end_src

2) Import the module in the configuration:

   #+begin_src nix configuration.nix

     [...]
       imports = [
       [...]
       (unstable + "/nixos/modules/services/matrix/mautrix-signal.nix")
     ];

     [...]
   #+end_src

* Build a firefox addon


#+begin_src nix configuration.nix
  programs.firefox = {
    [...]
     profiles.default = {
       [...]
       extensions = with pkgs.nur.repos.rycee.firefox-addons; [
         [...]
         (buildFirefoxXpiAddon {
           pname = ":emoji:";
           version = "0.1.3";
           addonId = "gonelf@gmail.com";
           url = "https://addons.mozilla.org/firefox/downloads/file/3365324/emojidots-0.1.3.xpi";
           sha256 = "4f7cc25c478fe52eb82f37c9ff4978dcaa3f95020398c5b184e517f6efa2c201";
           meta = with lib;
             {
               description = "emoji autocomplete anywhere on the internet";
               mozPermissions = [ "https://gist.githubusercontent.com/gonelf/d8ae3ccb7902b501c4a5dd625d4089da/raw/5eeda197ba92f8c8139e846a1225d5640077e06f/emoji_pretty.json" "tabs" "storage"];
               platforms = platforms.all;
             };
         })
   [...]
#+end_src

* Define shell utility as package

#+begin_src nix configuration.nix

  home.packages = with pkgs; [ # or for NixOS environment.systemPackages = with pkgs; [
    [...]
    (pkgs.writeShellApplication {
        name = "pass-fuzzel";
        runtimeInputs = [ pkgs.pass pkgs.fuzzel ];
        text = ''
         shopt -s nullglob globstar

         typeit=0
         if [[ $# -ge 1 && $1 == "--type" ]]; then
           typeit=1
           shift
         fi

         export PASSWORD_STORE_DIR=~/.local/share/password-store
         prefix=''${PASSWORD_STORE_DIR-~/.local/share/password-store}
         password_files=( "$prefix"/**/*.gpg )
         password_files=( "''${password_files[@]#"$prefix"/}" )
         password_files=( "''${password_files[@]%.gpg}" )

         password=$(printf '%s\n' "''${password_files[@]}" | fuzzel --dmenu "$@")

         [[ -n $password ]] || exit

         if [[ $typeit -eq 0 ]]; then
           pass show -c "$password" &>/tmp/pass-fuzzel
         else
           pass show "$password" | { IFS= read -r pass; printf %s "$pass"; } | wtype -
         fi
         notify-send -u critical -a pass -t 1000 "Copied/Typed Password"
       '';
      })

    [...]

#+end_src

* Add program with prebuild binaries to nix store

#+begin_src nix configuration.nix

  home.packages = with pkgs; [ # or for NixOS environment.systemPackages = with pkgs; [
    [...]
     (stdenv.mkDerivation {
      name = "oama";

      src = pkgs.fetchurl {
          name = "oama";
          url = "https://github.com/pdobsan/oama/releases/download/0.13.1/oama-0.13.1-Linux-x86_64-static.tgz";
          sha256 = "sha256-OTdCObVfnMPhgZxVtZqehgUXtKT1iyqozdkPIV+i3Gc=";
      };

      phases = [
        "unpackPhase"
      ];

      unpackPhase = ''
      mkdir -p $out/bin
      tar xvf $src -C $out/
      mv $out/oama-0.13.1-Linux-x86_64-static/oama $out/bin/
      '';

  })

    [...]
  #+end_src

* Patch a utilty for nix paths:
See https://drakerossman.com/blog/how-to-patch-a-package-source-on-nixos