freetop — NixOS configuration

A NixOS flake for a single host, freetop (HP laptop, Intel, GNOME on Wayland). Home Manager is wired in as a NixOS module, so everything — system and user — is applied by one nixos-rebuild switch.

• NixOS: 26.05
• User: mambuco
• Desktop: GNOME / Wayland, Catppuccin Macchiato
• Shell: fish + starship
• Disk: LUKS2 → btrfs subvolumes, Secure Boot via lanzaboote

Layout

flake.nix                  entry point → nixosConfigurations.freetop
disko.nix                  declarative disk layout, for fresh installs only
hosts/freetop/             the only place that knows it's "freetop"
  default.nix              imports modules + hardware, sets hostName/stateVersion
  hardware-configuration.nix
modules/<name>/default.nix  one folder per system concern (boot, desktop, …)
home/mambuco/<name>/        one folder per user concern (cli, gnome, theme, …)

Every concern is its own folder with a default.nix. A folder gains extra files only when a concern is big enough to section (e.g. home/mambuco/theme/ splits into default.nix + gnome-catppuccin.nix + cursor.nix; home/mambuco/gnome/ splits default.nix + apps.nix).

To add a concern: create modules/<name>/default.nix (or home/mambuco/<name>/default.nix) and add it to the imports list in hosts/freetop/default.nix (or home/mambuco/default.nix).

Everyday use

sudo nixos-rebuild switch --flake /etc/nixos#freetop

Update inputs (Claude/Zed inputs also refresh weekly via a systemd timer):

nix flake update --flake /etc/nixos

Installing on a new machine (disko)

disko.nix describes the whole disk declaratively — partitions, LUKS, the btrfs subvolumes and the swapfile — so a reinstall is a couple of commands instead of manual fdisk/cryptsetup/mkfs. It is not imported by the running system (freetop already has its disks); it is only run by the disko tool at install time. ⚠️ it erases the target disk.

From the NixOS installer ISO:

# 0. get this repo (git clone … or copy it onto the installer)

# 1. point disko.nix at the target disk if it isn't /dev/nvme0n1
lsblk
$EDITOR disko.nix          # set disk.main.device

# 2. partition + format + mount everything under /mnt (prompts for the LUKS
#    passphrase). This is the destructive step.
sudo nix --experimental-features "nix-command flakes" \
  run github:nix-community/disko/latest -- \
  --mode destroy,format,mount ./disko.nix

# 3. generate hardware-configuration.nix for THIS machine (disko already made
#    the filesystems, so keep them out of the generated file)
sudo nixos-generate-config --no-filesystems --root /mnt

# 4. put the flake in place and install
sudo cp -r . /mnt/etc/nixos
sudo nixos-install --flake /mnt/etc/nixos#freetop

# 5. reboot; then enroll Secure Boot keys once (lanzaboote): `sudo sbctl enroll-keys`

What each disko mode does: destroy wipes existing partitions, format writes the new partition table + filesystems, mount mounts them under /mnt ready for nixos-install. Test changes to disko.nix in a VM before trusting them on real hardware — it is destructive by design.

Notes for anyone reusing this

• modules/networking/ sets a personal NextDNS resolver hostname (…dns.nextdns.io) — replace it with your own profile or a public resolver.
• hosts/freetop/hardware-configuration.nix is machine-specific (disk UUIDs, kernel modules). Regenerate it on new hardware (step 3 above).
• SSH/vault secrets are not in this repo. The SSH key lives on disk (~/.ssh/id_ed25519, created manually) and is protected at rest by LUKS.

License

MIT — see LICENSE.