nixdots/guides/installation.md

Installation

This is a full NixOS installation guide, from live cd to a working OS. Once done, you will be left with a complete system, that uses my configuration.

This installation will push to use flakes out of the box, configuration.nix will only be needed to add support for flakes and rebuild.

Live ISO

This assumes you've chosen one of the ISO images with a graphical installer, and followed though with the installation, getting you to a basic NixOS installation.

During this installation, make sure you allow non-free programs, and in the desktop environment selection, pick the option without any DE, we'll get to install that ourselves.

Set up configuration.nix

Out of the box, NixOS only comes with nano editor, so we'll have to use that to edit the configuration.nix for the first time.

sudo nano configuration.nix

In there, change the environment.systemPackages = with pkgs; []; like, and include git and vim.

After that, let's enable flakes, by adding the following anywhere in your configuration.nix:

nix.package = pkgs.nixUnstable;
nix.settings.experimental-features = [ "nix-command" "flakes" ];

Now you can save the changes and rebuild the system:

sudo nixos-rebuild switch

Set up flakes

An interesting things about nix flakes, is that they need to live in a git repository, you won't be able to rebuild otherwise, so let's set up some git settings, so that we can make commits:

git config --global user.email "itsdrike@protonmail.com"
git config --global user.name "ItsDrike"

We could create and manage this repository directly in /etc/nixos, however that's not practical, since we probably want to use our git config and generally just work in a non-root environment when editing the flake. I like using the ~/dots directory.

cp -r /etc/nixos ~/dots
cd ~/dots

Now we have 2 options, the first one I'll show will set up my configuration from this repository. Once done, you will have your system set up in the same way that I do. In the second option, I will go over a basic setup to create your own flake.

Create your own custom flake

Initialize an empty git repository:

git init

Create a very basic ./flake.nix:

{
    description = "ItsDrike's NixOS configuration";

    inputs = {
      # the version here should match your system.stateVersion in configuration.nix
      nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.11";
    };

    outputs = { self, nixpkgs, ...} @ inputs: {
        nixosConfigurations = {
            nixos = nixpkgs.lib.nixosSystem {
                system = "x86_64-linux";
                modules = [ ./configuration.nix ];
            };
        };
    };
}

Let's add things to git!

git add flake.nix
git add configuration.nix
git add hardware-configuration.nix

Now you can rebuild the system to use our flake:

sudo nixos-rebuild switch --flake .

Yay, you're now using NixOS in flakes mode!

Note

If you run the sudo nixos-rebuild switch command, without the --flake . it would look for the flake.nix file in /etc/nixos.

Tip

Notice the nixosConfigurations (plural) key in our flake, suggesting that it can hold multiple configurations. Indeed, it can! You can use a single flake to manage multiple systems.

The name for the configuration just needs to match the hostname of your machine, which by default will be nixos.

Alternatively, you can also pick which configuration to use manually in the rebuild command, like so: nixos-rebuild --flake .#my-configuration, which would pick a config named my-configuration.

You can notice that this also created a flake.lock file, containing the exact versions of all of the packages you're using. Let's add this file to git too: git add flake.lock.

And now we're ready to make our first commit:

git commit -m "Initial commit"

Updating

Over time, you'll want to update the software that's installed on your machine, to do that, we'll first want to update the flake.lock file, which contains the commit sha of the nixpkgs repo that's being used. To do so, you can use this command (while in ~/dots directory):

nix flake update

After which, you'll probably also want to rebuild your system and switch:

nixos-rebuild switch --flake .

Tip

This replaces the legacy (non-flake) regime's command: nixos-rebuild switch --upgrade