My NixOS Configuration

This repository contains my personal NixOS configuration, structured using a dendritic pattern powered by flake-parts and import-tree.

This architecture allows for modular evaluation of standard flake outputs, splitting features, overlays, packages, and host configurations into distinct files that are elegantly discovered through import-tree rather than manually maintained arrays of imports.

Project Structure

Every .nix file under modules/ is a flake-parts module picked up automatically by import-tree, so adding a feature only means creating a file (and git add-ing it, since flakes only see tracked files). Each file defines one flake.nixosModules.<name> or flake.homeModules.<name>; hosts then choose which ones to import.

modules/
├── parts.nix                 # flake-parts setup (systems, home-manager flake module)
├── common/                   # reusable across hosts
│   ├── bundles/              # bundle* modules grouping related features (core-system, desktop, dev)
│   ├── nixos/                # NixOS features (one per file, e.g. fonts, sound, noctalia)
│   ├── home/                 # home-manager features (hm*, e.g. hmGit)
│   ├── overlays/             # nixpkgs overlays; default.nix applies all of them
│   └── packages/             # local packages exposed under `packages.<system>`
└── hosts/
    └── nixos-pc/
        ├── default.nix       # nixosConfigurations.nixos-pc: the only place listing imported modules
        ├── configuration.nix # host settings (hostname, locale, nix settings, …)
        ├── hardware.nix      # generated by nixos-generate-config
        ├── user.nix
        ├── features/         # nixosPc* modules specific to this machine (firewall, sudo, suspend, packages, …)
        └── home/hiepnh/      # home-manager config for hiepnh on this host

Naming conventions

Kind	Location	Module name
Common NixOS feature	common/nixos/foo-bar.nix	nixosModules.fooBar
Common home-manager feature	common/home/hm-foo.nix	homeModules.hmFoo
Bundle	common/bundles/foo.nix	nixosModules.bundleFoo / homeModules.bundleFoo
Host-specific module	hosts/<host>/features/foo.nix	nixosModules.<host>Foo (e.g. nixosPcFirewall)

Common modules should not hardcode a user or machine; set those values from the host (e.g. services.fcitx5-lotus.user in hosts/nixos-pc/configuration.nix).

Installing on a New Machine

Some flake inputs (fcitx5-jot, jotty, keywave, unda, wayshadow) are private GitHub repositories fetched over SSH, so the installer needs an SSH key registered on GitHub before it can evaluate the flake. Prebuilt binaries of these packages are served from justanoobcoder.cachix.org, so they are downloaded instead of rebuilt (as long as the cache was pushed after the last rebuild).

The steps below work from the minimal (no desktop) NixOS ISO. GitHub login uses the device flow, so you only need a phone or another device with a browser.

1. Prepare the live environment

Boot the ISO, connect to the network, then become root (nixos-install runs as root, so the SSH key must belong to root):

sudo -i
nix-shell -p gh git

2. Authenticate with GitHub

gh auth login

Answer the prompts:

• Where do you use GitHub? → GitHub.com
• Preferred protocol for Git operations? → SSH
• Generate a new SSH key? → Yes (optionally set a passphrase)
• Title for your SSH key → something identifiable, e.g. nixos-installer
• How would you like to authenticate? → Login with a web browser

gh prints a one-time code. Open https://github.com/login/device on your phone, enter the code and approve. gh then uploads the new public key to your GitHub account.

Verify:

ssh -T git@github.com

3. Partition, format and mount

Partition and mount the target disk under /mnt as usual (see the NixOS manual).

4. Clone the configuration

mkdir -p /mnt/home/hiepnh
git clone git@github.com:justanoobcoder/nixcfg.git /mnt/home/hiepnh/.nixcfg

5. Update the hardware configuration

If the hardware differs from the previous machine, regenerate it and merge the relevant parts (filesystems, kernel modules, etc.) into modules/hosts/nixos-pc/hardware.nix:

nixos-generate-config --root /mnt --show-hardware-config

6. Install

nixos-install --flake /mnt/home/hiepnh/.nixcfg#nixos-pc

Set the root password when prompted, then set the user password:

nixos-enter --root /mnt -c 'passwd hiepnh'

7. Keep the SSH key (optional)

The key generated in step 2 lives in the live environment's RAM and is lost on reboot. Either copy it to the new system:

mkdir -p /mnt/home/hiepnh/.ssh
cp ~/.ssh/id_ed25519* /mnt/home/hiepnh/.ssh/
nixos-enter --root /mnt -c 'chown -R hiepnh:users /home/hiepnh/.ssh /home/hiepnh/.nixcfg && chmod 600 /home/hiepnh/.ssh/id_ed25519'

Or, after rebooting, run gh auth login again as hiepnh to create a new key, and delete the nixos-installer key from https://github.com/settings/keys.

8. Rebuilding afterwards

Run rebuilds as your user (not sudo nixos-rebuild) so private inputs are fetched with your own SSH key:

nixos-rebuild switch --flake ~/.nixcfg#nixos-pc --sudo

Updating the binary cache

After updating the private inputs (or nixpkgs) and rebuilding, push the new builds so the next reinstall can download them:

nix path-info -r /run/current-system | grep -E 'jot|jotty|keywave|unda|wayshadow' | grep -v -- '-source$'
cachix push justanoobcoder <store paths of the main packages>