Kzk's garden

Nix

4 min read

public:: true

  • Install

  • How nix work

    • Nix Store everything in the nix store usually at /nix/store

    • Nix profiles make the package visible to the user, a profile describes an environment normally don with nix-env

      nix-env -i package_name.  ## install a package in the default profile
nix-env --query "*"       ## query packages in the current profile
nix-env -e package_name.  ## remove a package in the current profile
nix-env --rollback.       ## rollback to a previous generation

    • Channels: is a repository with packages for nix

      nix-channel --list
nix-channel --add https://nixos.org/channels/nixpkgs-unstable unstable
nix-channel --update
 
nix-env -iA unstable.simgrid  ## Install simgrid from the unstable

    • packages

      nix-env upgrade simgrid
nix search nixpkgs simgrid

    • Shells: makes visible packages of an specific profile to a new shell (like virtualenv)

      nix-shell

    • echo ‘experimental-features = nix-command flakes’ >> /etc/nix/nix.conf

  • Nix as build tool

    • Nix can be used as a tool to build software in a consistent manner

      {
pkgs ? import (fetchTarball {
  url = "https://github.com/NixOS/nixpkgs/archive/4fe8d07066f6ea82cda2b0c9ae7aee59b2d241b3.tar.gz";
  sha256 = "sha256:06jzngg5jm1f81sc4xfskvvgjy5bblz51xpl788mnps1wrkykfhp";
}) {}
}:
pkgs.stdenv.mkDerivation rec {
pname = "chord";
version = "0.1.0";

src = pkgs.fetchgit {
  url = "https://gitlab.inria.fr/nix-tutorial/chord-tuto-nix-2022";
  rev = "069d2a5bfa4c4024063c25551d5201aeaf921cb3";
  sha256 = "sha256-MlqJOoMSRuYeG+jl8DFgcNnpEyeRgDCK2JlN9pOqBWA=";
};

buildInputs = [
  pkgs.simgrid
  pkgs.boost
  pkgs.cmake
];

configurePhase = ''
  cmake .
'';

buildPhase = ''
  make
'';

installPhase = ''
  mkdir -p $out/bin
  mv chord $out/bin
'';
}

      nix-build chord.nix

  • Build to create a docker image

    • {
pkgs ? import (fetchTarball {
  url = "https://github.com/NixOS/nixpkgs/archive/4fe8d07066f6ea82cda2b0c9ae7aee59b2d241b3.tar.gz";
  sha256 = "sha256:06jzngg5jm1f81sc4xfskvvgjy5bblz51xpl788mnps1wrkykfhp";
}) {}
}:

with pkgs;

let
packages = rec {
  chord-docker = dockerTools.buildImage {
    name = "chord-docker";
    tag = "tuto-nix";
    contents = [ chord ];
    config = {
      Cmd = [ "${chord}/bin/chord" ];
      WorkingDir = "/data";
      Volumes = { "/data" = { }; };
    };
  };
};
in
packages

      nix-build default.nix -A chord-docker

      This will generate a result tarball thar we need to load into docker

      docker load < result

  • Example of how to use nix-shell

    collapsed:: true 
    •  This shell defines a development environment for the Chord project.
{
pkgs ? import (fetchTarball {
  url = "https://github.com/NixOS/nixpkgs/archive/4fe8d07066f6ea82cda2b0c9ae7aee59b2d241b3.tar.gz";
  sha256 = "sha256:06jzngg5jm1f81sc4xfskvvgjy5bblz51xpl788mnps1wrkykfhp";
}) {}
}:
pkgs.mkShell rec {
 buildInputs = with pkgs; [
  cmake
  boost
  simgrid

  # debugging tools
  gdb
  valgrind
 ];
}

      nix-shell shell.nix

  • What is a Flake

    • flake is just lockfiles for your nix configuration
    • since nix uses channels, is not 100% reproducible… you change the channels and your packages may or may not work.
    • with flakes… it will generate a lock files to ensure specific packages were used
    • to autocomplete my nix-darwin configuration I use this .nixd.json
    • {
    "options": {
        "enable": true,
        "target": {
            "args": [
                "--expr",
                "(import <darwin> { configuration = ./darwin-configuration.nix; }).options"
            ],
            "installable": ""
        }
    }
}

  • What is home-manager

    • Home manager is a way to configure all user configuration
    • from which applications are visible to this user
    • to modify $HOME files

  • What is NixOS

    • an linux distribution that everything is configured with nix
    • modify the /etc/nixos/configuration.nix file
    • and execute nixos-rebuild switch
    • if for some reason, something fails, you can rollback to previous versions, and if the kernel crashes, the bootloader shows you all previous configurations to boot from

  • Nix LSP

    • I like to use nixd → https://github.com/nix-community/nixd
    • you can install it with 
      • nix-env -iA nixpkgs.nixd
    • To configure it for your use, need a .nixd.json file that tell how to import

  • Configuration syntax

    • { config, pkgs, ... }:

{
  environment.shells = [ pkgs.zsh ];
  
  homebrew.
  # List packages installed in system profile. To search by name, run:
  # $ nix-env -qaP | grep wget
  environment.systemPackages =
    [ pkgs.neovim
    ];

  # Use a custom configuration.nix location.
  # $ darwin-rebuild switch -I darwin-config=$HOME/.config/nixpkgs/darwin/configuration.nix
  # environment.darwinConfig = "$HOME/.config/nixpkgs/darwin/configuration.nix";

  # Auto upgrade nix package and the daemon service.
  services.nix-daemon.enable = true;
  # nix.package = pkgs.nix;

  # Create /etc/zshrc that loads the nix-darwin environment.
  programs.zsh.enable = true;  # default shell on catalina
  # programs.fish.enable = true;

  # Used for backwards compatibility, please read the changelog before changing.
  # $ darwin-rebuild changelog
  system.stateVersion = 4;
}
    • { config, pkgs, ... }: {} → means!
      • the whole file is a function, with a single parameter
      • this parameter is a set that need to have config and pkgs keys
      • and the function returns a new set
    • with
      • environment.shells = [ pkgs.zsh ]; could be rewritten as environment.shells = with pkgs; [ zsh ];
    • inherith
    • import → imports a module, could be a relative file, or a search in nix path file with < > angular brackets

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