Matthias' Nix Configuration Flake

A modular, multi-platform Nix flake managing NixOS, Nix-Darwin, and standalone Home Manager configurations using flake-parts and the dendritic pattern.
Check out the vanilla branch for a more "vanilla" Nix Flake setup.

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Overview

This flake manages system configuration across three platforms:

• NixOS - full system configuration for Linux hosts
• nix-darwin - system configuration for macOS hosts
• Home Manager (standalone) - user environment for non-NixOS Linux hosts
• Dev Shells - reproducible development environments via nix develop
• Packages - standalone applications (e.g. neovim via nixvim) runnable with nix run

Architecture

The flake uses flake-parts with import-tree to automatically load all modules from the modules/ directory. Configuration is split into small, composable modules following the dendritic pattern. Modules are organized by feature, not by target OS, and hosts compose exactly what they need.

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Hosts

NixOS

Host	WM / DE	Shell	Terminal	Notes
beelink	Hyprland	Noctalia	Kitty	Desktop
work	Hyprland	Noctalia	Kitty	Laptop
vm	None	None	Nonve	None

Nix-Darwin

Host	WM	Shell	System	Notes
intel	None	Zsh	x86_64-darwin	MacBook Intel
m1	HyprSpace	Zsh	aarch64-darwin	MacBook Air M1
work	HyprSpace	Zsh	aarch64-darwin	MacBook Air M3

Standalone Home Manager

Host	System	Notes
pacman	x86_64-linux	Any Linux distro with Nix installed

All hosts

Shell	Editors	Terminal
Zsh + p10k	Neovim (nixvim)	Kitty

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Installation

NixOS

# Clone the repo
git clone https://github.com/matthiasbenaets/nix-config ~/.setup
cd ~/.setup

# Switch to a host configuration
sudo nixos-rebuild switch --flake <path/to/flake>#<host>

# Example
sudo nixos-rebuild switch --flake .#beelink

Nix-Darwin

First install Nix if not present:

sh <(curl --proto '=https' --tlsv1.2 -L https://nixos.org/nix/install)

Enable flakes:

mkdir -p ~/.config/nix
echo "experimental-features = nix-command flakes" >> ~/.config/nix/nix.conf

First build (darwin-rebuild not yet in PATH):

nix-env -iA nixpkgs.git
git clone https://github.com/matthiasbenaets/nix-config ~/.setup
cd ~/.setup
nix build .#darwinConfigurations.<host>.system
./result/sw/bin/darwin-rebuild switch --flake ~/.setup#<host>

Subsequent rebuilds:

darwin-rebuild switch --flake ~/.setup#<host>

Standalone Home Manager

First install Nix and Home Manager (and Flatpak):

sh <(curl --proto '=https' --tlsv1.2 -L https://nixos.org/nix/install) --daemon
nix-channel --add https://github.com/nix-community/home-manager/archive/master.tar.gz home-manager
nix-channel --update
nix-shell '<home-manager>' -A install

# Ubuntu for flatpak
echo "kernel.unprivileged_userns_clone=1" | sudo tee /etc/sysctl.d/99-userns.conf \
&& echo "kernel.apparmor_restrict_unprivileged_userns=0" | sudo tee /etc/sysctl.d/99-flatpak.conf \
&& sudo sysctl --system

Get and rebuild:

nix-env -iA nixpkgs.git
git clone https://github.com/matthiasbenaets/nix-config ~/.setup
cd ~/.setup
home-manager switch --extra-experimental-features 'nix-command flakes' --flake ~/.setup#<host>

NixGL is no longer required when running home-manager on a generic Linux host.
However on first rebuild, you might need to run the command below to link the GPU using a service.

sudo /nix/store/<sha>-non-nixos-gpu/bin/non-nixos-gpu-setup

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Adding a New Host

Thanks to the dendritic structure and import-tree, adding a new host is a straightforward process that doesn't require modifying the main flake.nix.

Here's how to add a new NixOS host (the process is similar for nix-darwin and home-manager):

1. Create a Host Directory: Create a new directory for your host under modules/hosts/nixos/. Let's call it my-new-host:

   mkdir modules/hosts/nixos/my-new-host

2. Create a default.nix: Inside the new directory, create a default.nix file. This is where you'll define your host's configuration. You can use an existing host as a template.

3. Define the Host Configuration: In modules/hosts/nixos/my-new-host/default.nix, define the nixosConfiguration for your host. It should look something like this:

   {
     config,
     inputs,
     ...
   }:
   
   let
     host = {
       name = "my-new-host";
       user.name = "your-username";
       state.version = "23.11"; // Or your desired version
       system = "x86_64-linux";
     };
   in
   {
     flake.nixosConfigurations.my-new-host = inputs.nixpkgs.lib.nixosSystem {
       modules = with config.flake.modules.nixos; [
         # Import the modules you need
         base
         my-new-host # a module for host specific configuration
   
         # Example modules:
         audio
         nixvim
         gnome
       ];
     };
   
     # Host-specific module
     flake.modules.nixos.my-new-host = {
       inherit host;
       home-manager.users.${host.user.name} = {
         imports = with config.flake.modules.homeManager; [
           # Home-manager modules
           kitty
         ];
       };
     };
   }

4. Build Your Host: Once you've created the default.nix, you can build your new host configuration:

   sudo nixos-rebuild switch --flake .#my-new-host

This structure allows you to keep your host-specific configurations isolated while re-using the modules defined in the rest of the flake.

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Packages

Standalone packages can be run directly without installing them system-wide.

Package	Description
neovim	Neovim configured via nixvim

# Run directly
nix run .#neovim

# Run from anywhere using the flake URL
nix run github:matthiasbenaets/nix-config#neovim

# Add temporarily to PATH
nix shell .#neovim

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Dev Shells

Pre-configured development environments with all relevant tools available.

Shell	Tools
default	vim, git
neovim	Configured neovim + git
python	Python tooling
nodejs	nodejs, npm with local prefix configured

# Enter a shell
nix develop .#<shell>

# Examples
nix develop .#nodejs
nix develop .#python
nix develop            # enters default shell

Note: Dev shells use nix develop. nix run and nix shell are for packages, not dev shells.

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Maintenance

Garbage Collection

Nix stores all packages in the /nix/store, and over time this can grow quite large. You can remove unused packages (garbage) to free up space.

To remove all packages that are not referenced by any user profile or configuration:

nix-store --gc

To see what would be deleted without actually deleting it:

nix-store --gc --print-dead

You can also free up more space by optimising the nix store:

nix-store --optimise

It's also possible to clean for the current user or system wide:

nix-collect-garbage -d
sudo nix-collect-garbage -d

---

Development Reference

Evaluating Configurations

Use these commands to check if a configuration evaluates without errors:

nix eval <path/to/flake>#nixosConfigurations.<host>.config.system.build.toplevel --show-trace
nix eval <path/to/flake>#darwinConfigurations.<host>.config.system.build.toplevel --show-trace
nix eval <path/to/flake>#homeConfigurations.<host>.activationPackage --show-trace
nix eval <path/to/flake>#<package> --show-trace

Updating Inputs

# Update all inputs
nix flake update

# Update a specific input
nix flake update nixpkgs

Updating Channels

sudo nix-channel --list
sudo nix-channel --remove <name>
sudo nix-channel --add <channel url> <name>
sudo nix-channel --update

Checking Flake Outputs

nix flake show