Nix Flakes

From: Nix, NixOS, Home Manager.

Flakes are an experimental feature of Nix which allow users to manage their NixOS configuration outside of /etc/nixos/configuration.nix, and add it to something like a Git repository.

A "flake" is a set of files which contains a valid flake.nix entrypoint. Much like how a Node package is a set of files which contains a valid package.json and index.js.

Getting started

Migrating to Flakes on NixOS

1. Enable the experimental feature in your /etc/nixos/configuration.nix

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

Rebuild and switch.

2. Start a new flake (preferably in a Git repository)

nix flake init

# Might want this, too
git init

3. Copy your system and hardware configurations into your new repository

# Assuming you're in the repository
sudo cp /etc/nixos/*.nix .

4. Edit the initial flake.nix to include your previous system configuration as a module

{
  description = "flake for my computer";

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

  outputs = {
    self,
    nixpkgs,
    ...
  } @ inputs: let
    system = "x86_64-linux";
    pkgs = nixpkgs.legacyPackages.${system};
  in {
    nixosConfigurations = {
      <your computer> = nixpkgs.lib.nixosSystem {
        specialArgs = {inherit inputs;};
        modules = [ ./configuration.nix ];
      };
    };
  };
}

Note

Ensure you replace <your computer> with your computer's host name.

5. Check in all the files into your Git repository

# Make sure EVERYTHING gets checked in!
git add .
git commit -m "feat: init flake"

6. Rebuild using the flake instead of your system configuration

sudo nixos-rebuild switch --flake .

Inputs

To add another flake:

inputs = {
    # Both flakes
    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
    nur.url = "github:nix-community/NUR";
};

To add non-flakes:

inputs = {
    toggleterm-manager = {
        url = "github:ryanmsnyder/toggleterm-manager.nvim";
        flake = false;
    };
}

To add private repositories:

inputs = {
    my-private-repo = {
        url = "git+ssh://[email protected]/username/my-private-repo";
        flake = false;
    };
}