Nix Expressions

tour of Nix

nix eval --exp '(x: y: { a = x + "-" + y; }) "Datenspuren" "2022"'
        

❯ nix repl
Welcome to Nix 2.9.1. Type :? for help.

nix-repl> (x: y: { a = x + "-" + y; }) "Datenspuren" "2022"
{ a = "Datenspuren-2022"; }
        

Nix Derivation

with import <nixpkgs> {}; stdenv.mkDerivation {
   name = "hello";
   src = ./src;
   buildInputs = [ coreutils gcc ];
   configurePhase = ''
     declare -xp
   '';
   buildPhase = ''
     gcc "$src/hello.c" -o ./hello
   '';
   installPhase = ''
     mkdir -p "$out/bin"
     cp ./hello "$out/bin/"
   '';
}

Trivial Builder

with import <nixpkgs> {};
  runCommand "name" {envVariable = true;} ''echo hello > $out''

Nix Store

• nur lesbar
• wird nur vom Nix Package Manager geschrieben

/nix/store/$(cryptographic-hash)-$(package-name)-$(version)/$(package-contents)

❯ ls /nix/store/*hello*
/nix/store/g4dl2djh719933klf04bmmrjdswfpzip-hello-2.10.tar.gz.drv
/nix/store/qpskxiffl94sy3awnwprra2id9r911zr-hello-2.10.drv
/nix/store/dd617z4bscvvv6i0d9d1x2ml96pi04nk-hello-2.10:
    bin share
        
        

Nix Store

Nix Modules

Organisationsstruktur für Betriebssystem-komponenten und Dienste mit Konfigurationsoptionen

search.nixos.org/options

oder

man configuration.nix

Nix Modules

{ config, lib, pkgs, ... }:
with lib;
let
  cfg = config.services.uptimed;
  stateDir = "/var/lib/uptimed";
in
{
  options = {
    services.uptimed = {
      enable = mkOption {
        type = types.bool;
        default = false;
        description = lib.mdDoc ''
          Enable `uptimed`, allowing you to track
          your highest uptimes.
        '';
      };
    };
  };

  config = mkIf cfg.enable {
    environment.systemPackages = [ pkgs.uptimed ];
    users.users.uptimed = {
      description = "Uptimed daemon user";
      home        = stateDir;
      uid         = config.ids.uids.uptimed;
      group       = "uptimed";
    };
    users.groups.uptimed = {};
    systemd.services.uptimed = {
      description = "uptimed service";
      wantedBy    = [ "multi-user.target" ];
      serviceConfig = {
        Restart                 = "on-failure";
        User                    = "uptimed";
        StateDirectory          = [ "uptimed" ];
        ExecStart               = "${pkgs.uptimed}/sbin/uptimed -f -p ${stateDir}/pid";
      };
    };
  };
}
        

Nix Flakes

{
  outputs = { self }: {
    foo = "Datenspuren";
  };
}

{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs";
  };

  outputs = { self, nixpkgs }: {
    packages.x86_64-linux.hello = nixpkgs.legacyPackages.x86_64-linux.hello;
  };
}

Nix Flakes