refactor: make nanuqsaurus module-based; keep btrfs install profile

README.md

@@ -1,13 +1,19 @@
 > under heavy development
 
-## Install in place
+## Adopt on an existing NixOS install (recommended)
+
+Use a small local wrapper flake that imports this repo’s profile module and keeps
+your machine’s `hardware-configuration.nix` for mounts/boot:
+
+- `docs/adopt.md`
+
+## Fresh install (wipes disk, uses disko)
 
 ```
-sudo nixos-rebuild switch --flake "git+https://codeberg.org/randogoth/nanuqsaurus.git#nanuqsaurus"
+sudo nix --experimental-features "nix-command flakes" \
-```
+  run github:nix-community/disko/latest#disko-install -- \
-
+  --mode format \
-## Install to a mounted target root (/mnt)
+  --flake "git+https://codeberg.org/randogoth/nanuqsaurus.git#nanuqsaurus-btrfs" \
-
+  --disk main /dev/disk/by-id/<your-disk> \
-```
+  --mount-point /mnt
-sudo nixos-install --root /mnt --flake "git+https://codeberg.org/randogoth/nanuqsaurus.git#nanuqsaurus"
 ```

docs/adopt.md

@@ -0,0 +1,64 @@
+# Adopt Nanuqsaurus on an existing NixOS install (no repartitioning)
+
+This repo intentionally does **not** ship a “one size fits all” `nixosConfiguration` for installed systems.
+Disk layouts, filesystems, initrd modules, and bootloader details are machine-specific and live in your
+local `hardware-configuration.nix`.
+
+The recommended workflow is to create a **small local wrapper flake** that:
+
+- keeps your machine’s `hardware-configuration.nix` as the source of truth for mounts/boot,
+- imports `nanuqsaurus` as a feature/profile module from its URL,
+- keeps your personal changes in your own repo (or `/etc/nixos`).
+
+## 1) Create a wrapper flake in `/etc/nixos`
+
+On the target machine:
+
+1. Ensure you have a `hardware-configuration.nix` (generated by `nixos-generate-config`).
+2. Create `/etc/nixos/flake.nix` like this (adjust `hostName` and `stateVersion`):
+
+```nix
+{
+  description = "Local wrapper for the nanuqsaurus profile";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.11";
+    nanuqsaurus.url = "git+https://codeberg.org/randogoth/nanuqsaurus.git";
+    nanuqsaurus.inputs.nixpkgs.follows = "nixpkgs";
+  };
+
+  outputs =
+    { self, nixpkgs, nanuqsaurus, ... }:
+    {
+      nixosConfigurations.my-host = nixpkgs.lib.nixosSystem {
+        system = "x86_64-linux";
+        modules = [
+          ./hardware-configuration.nix
+          nanuqsaurus.nixosModules.nanuqsaurus
+
+          # Your local overrides/customizations:
+          ({ ... }: {
+            # Optional: change the default admin username ("admin")
+            nanuqsaurus.admin.username = "admin";
+            networking.hostName = "my-host";
+            system.stateVersion = "25.11";
+          })
+        ];
+      };
+    };
+}
+```
+
+## 2) Switch to it
+
+```bash
+sudo nixos-rebuild switch --flake /etc/nixos#my-host
+```
+
+## Updating later
+
+- If you keep `nanuqsaurus.url` pointing at the repo, you can update with:
+  - `nix flake update` (in `/etc/nixos`), then
+  - `sudo nixos-rebuild switch --flake /etc/nixos#my-host`
+
+- Keep all your machine-specific changes in the wrapper flake (additional modules, packages, services, etc.).

docs/install-help.txt

@@ -13,20 +13,28 @@ Pick a stable disk path (prefer /dev/disk/by-id/*) and run:
     --disk main /dev/disk/by-id/<your-disk> \
     --mount-point /mnt
 
+Adopt an existing NixOS install (no repartition)
+-----------------------------------------------
+
+Create a small local wrapper flake that imports this repo as a module and keeps
+your machine’s `hardware-configuration.nix` for mounts/boot.
+
+See: docs/adopt.md (on the custom ISO: `/etc/nixos/docs/adopt.md`)
+
 
 ISO shortcut
 ------------
 
 If you are using the custom ISO from this repo, it embeds the flake at /etc/nixos.
-You can run the wrapper script (defaults: DISK=/dev/vda, TARGET_HOST=nanuqsaurus):
+You can run the wrapper script (defaults: DISK=/dev/vda, TARGET_HOST=nanuqsaurus-btrfs):
 
   sudo /etc/nixos/scripts/install-btrfs.sh
 
 
 Optionally set DISK, TARGET_HOST, and FLAKE:
 
-  sudo DISK=/dev/disk/by-id/<your-disk> TARGET_HOST=nanuqsaurus \
+  sudo DISK=/dev/disk/by-id/<your-disk> TARGET_HOST=nanuqsaurus-btrfs \
-    FLAKE="github:<owner>/<repo>" \
+    FLAKE="git+https://codeberg.org/<owner>/<repo>.git" \
     /etc/nixos/scripts/install-btrfs.sh
 
 

flake.nix

@@ -23,25 +23,24 @@
     inputs@{ self, nixpkgs, ... }:
     let
       lib = nixpkgs.lib;
-      hostFiles = builtins.attrNames (builtins.readDir ./hosts);
-      hostNames = lib.filter (
-        name: lib.hasSuffix ".nix" name && !(lib.hasSuffix "-hardware.nix" name) && name != "iso.nix"
-      ) hostFiles;
-      mkHost =
-        name:
-        lib.nixosSystem {
-          system = "x86_64-linux";
-          specialArgs = { inherit inputs; };
-          modules = [ (./hosts + "/${name}.nix") ];
-        };
     in
     {
-      nixosConfigurations = lib.genAttrs (map (lib.removeSuffix ".nix") hostNames) mkHost // {
+      nixosModules.nanuqsaurus = import ./modules/profile/nanuqsaurus.nix { inherit inputs; };
+
+      nixosConfigurations = {
+        # Live installer ISO (used to bootstrap installs).
         installer = nixpkgs.lib.nixosSystem {
           system = "x86_64-linux";
           specialArgs = { inherit inputs; };
           modules = [ ./hosts/iso.nix ];
         };
+
+        # Fresh-install profile that includes disko partitioning/layout.
+        nanuqsaurus-btrfs = nixpkgs.lib.nixosSystem {
+          system = "x86_64-linux";
+          specialArgs = { inherit inputs; };
+          modules = [ ./hosts/nanuqsaurus-btrfs.nix ];
+        };
       };
 
       packages.x86_64-linux.install-iso = self.nixosConfigurations.installer.config.system.build.isoImage;

hosts/nanuqsaurus-btrfs.nix

@@ -9,23 +9,8 @@
 {
   imports = [
     inputs.disko.nixosModules.disko
-    inputs.lix-module.nixosModules.lixFromNixpkgs
+    (import ../modules/profile/nanuqsaurus.nix { inherit inputs; })
-    inputs.nix-index-database.nixosModules.nix-index
-    inputs.nix-flatpak.nixosModules.nix-flatpak
-    ../modules/system/flatpak.nix
-    ../modules/system/base.nix
     ../modules/system/disko-btrfs.nix
-    ../modules/system/packages.nix
-    ../modules/system/shell.nix
-    ../modules/system/home-manager-skel.nix
-    ../modules/system/fonts.nix
-    ../modules/system/printer.nix
-    ../modules/desktop/desktop-entries.nix
-    ../modules/desktop/file-manager.nix
-    ../modules/desktop/gnome-minimal.nix
-    ../modules/development/flox.nix
-    ../modules/users/admin.nix
-    ./nanuqsaurus-hardware.nix
   ];
 
   networking.hostName = "nanuqsaurus";

hosts/nanuqsaurus.nix

@@ -1,74 +0,0 @@
-{
-  config,
-  pkgs,
-  lib,
-  inputs,
-  ...
-}:
-
-{
-  imports = [
-    inputs.lix-module.nixosModules.lixFromNixpkgs
-    inputs.nix-index-database.nixosModules.nix-index
-    inputs.nix-flatpak.nixosModules.nix-flatpak
-    ../modules/system/flatpak.nix
-    ../modules/system/base.nix
-    ../modules/system/packages.nix
-    ../modules/system/shell.nix
-    ../modules/system/home-manager-skel.nix
-    ../modules/system/fonts.nix
-    ../modules/system/printer.nix
-    ../modules/desktop/desktop-entries.nix
-    ../modules/desktop/file-manager.nix
-    ../modules/desktop/gnome-minimal.nix
-    ../modules/development/flox.nix
-    ../modules/users/admin.nix
-  ];
-
-  networking.hostName = "nanuqsaurus";
-
-  # Minimal defaults for adopting an existing disk layout.
-  # Override these in a site-local host module if your layout differs.
-  boot.initrd.availableKernelModules = lib.mkDefault [ "ahci" "xhci_pci" "virtio_pci" "sr_mod" "virtio_blk" ];
-  nixpkgs.hostPlatform = lib.mkDefault "x86_64-linux";
-
-  fileSystems."/" = lib.mkDefault {
-    device = "/dev/disk/by-partlabel/disk-main-nixos";
-    fsType = "btrfs";
-    options = [
-      "x-initrd.mount"
-      "compress=zstd"
-      "subvol=root"
-    ];
-  };
-
-  fileSystems."/home" = lib.mkDefault {
-    device = "/dev/disk/by-partlabel/disk-main-nixos";
-    fsType = "btrfs";
-    options = [
-      "compress=zstd"
-      "subvol=home"
-    ];
-  };
-
-  fileSystems."/nix" = lib.mkDefault {
-    device = "/dev/disk/by-partlabel/disk-main-nixos";
-    fsType = "btrfs";
-    options = [
-      "x-initrd.mount"
-      "compress=zstd"
-      "subvol=nix"
-    ];
-  };
-
-  fileSystems."/boot" = lib.mkDefault {
-    device = "/dev/disk/by-partlabel/disk-main-ESP";
-    fsType = "vfat";
-    options = [
-      "fmask=0022"
-      "dmask=0022"
-    ];
-  };
-
-  system.stateVersion = "25.11";
-}

modules/profile/nanuqsaurus.nix

@@ -0,0 +1,21 @@
+{ inputs }:
+{ ... }:
+{
+  imports = [
+    inputs.lix-module.nixosModules.lixFromNixpkgs
+    inputs.nix-index-database.nixosModules.nix-index
+    inputs.nix-flatpak.nixosModules.nix-flatpak
+    ../system/flatpak.nix
+    ../system/base.nix
+    ../system/packages.nix
+    ../system/shell.nix
+    ../system/home-manager-skel.nix
+    ../system/fonts.nix
+    ../system/printer.nix
+    ../desktop/desktop-entries.nix
+    ../desktop/file-manager.nix
+    ../desktop/gnome-minimal.nix
+    ../development/flox.nix
+    ../users/admin.nix
+  ];
+}

modules/system/home-manager-skel.nix

@@ -1,8 +1,15 @@
-{ ... }:
+{
+  config,
+  lib,
+  ...
+}:
 
 let
-  flakeText = (builtins.readFile ../../templates/home-flake.nix);
+  adminUser = lib.attrByPath [ "nanuqsaurus" "admin" "username" ] "admin" config;
-  homeText = (builtins.readFile ../../templates/home-home.nix);
+  substitute = text: lib.replaceStrings [ "@ADMIN_USER@" ] [ adminUser ] text;
+
+  flakeText = substitute (builtins.readFile ../../templates/home-flake.nix);
+  homeText = substitute (builtins.readFile ../../templates/home-home.nix);
 in
 {
   environment.etc = {

modules/users/admin.nix

@@ -1,12 +1,29 @@
-{ lib, pkgs, ... }:
-
 {
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+let
+  cfg = config.nanuqsaurus.admin;
+in
+{
+  options.nanuqsaurus.admin = {
+    username = lib.mkOption {
+      type = lib.types.str;
+      default = "admin";
+      description = "Primary admin user account name.";
+    };
+  };
+
+  config = {
     users.groups = {
       docker = { };
       podman = { };
     };
 
-  users.users.admin = {
+    users.users.${cfg.username} = {
       isNormalUser = true;
       extraGroups = [
         "wheel"
@@ -33,9 +50,9 @@
 
     security.sudo.wheelNeedsPassword = lib.mkDefault true;
 
-  # Bootstrap Home Manager for admin on first login (per-user, standalone)
+    # Bootstrap Home Manager for the primary admin user on first login (per-user, standalone)
     systemd.user.services.hm-bootstrap = {
-    description = "One-time Home Manager bootstrap for admin";
+      description = "One-time Home Manager bootstrap";
       unitConfig = {
         ConditionPathExists = "!%h/.config/home-manager/.hm_bootstrap_done";
         After = [ "graphical-session.target" ];
@@ -45,7 +62,11 @@
       serviceConfig = {
         Type = "simple";
         TimeoutStartSec = "30min";
-      Environment = [ "PATH=/run/current-system/sw/bin:/etc/profiles/per-user/%u/bin" ];
+        Environment = [
+          "PATH=/run/current-system/sw/bin:/etc/profiles/per-user/%u/bin"
+          "NANUQSAURUS_ADMIN_USER=${cfg.username}"
+          "NANUQSAURUS_HM_TARGET=${cfg.username}"
+        ];
         StandardOutput = "journal";
         StandardError = "journal";
         ExecStart = pkgs.writeShellScript "hm-bootstrap.sh" (
@@ -54,4 +75,5 @@
       };
       wantedBy = [ "graphical-session.target" ];
     };
+  };
 }

scripts/hm-bootstrap.sh

@@ -2,9 +2,12 @@
 set -euo pipefail
 
 UID="$(id -u)"
+USER_NAME="$(id -un)"
 USER_BUS="/run/user/$UID/bus"
 HM_DIR="$HOME/.config/home-manager"
 SKEL_DIR="/etc/skel/.config/home-manager"
+EXPECTED_USER="${NANUQSAURUS_ADMIN_USER:-}"
+HM_TARGET="${NANUQSAURUS_HM_TARGET:-$USER_NAME}"
 
 # Ensure basic PATH for user units
 export PATH="/run/current-system/sw/bin:${PATH:-}"
@@ -79,6 +82,10 @@ trap 'notify "Bootstrap finished" "Your system is fully hydrated. It is recommen
 
 # ---- Home Manager bootstrap -------------------------------------------------
 
+if [[ -n "$EXPECTED_USER" && "$USER_NAME" != "$EXPECTED_USER" ]]; then
+  exit 0
+fi
+
 mkdir -p "$HM_DIR"
 
 for f in flake.nix home.nix; do
@@ -88,5 +95,5 @@ for f in flake.nix home.nix; do
   install -m 600 "$src" "$dst"
 done
 
-home-manager switch --flake "$HM_DIR#admin"
+home-manager switch --flake "$HM_DIR#$HM_TARGET"
 touch "$HM_DIR/.hm_bootstrap_done"

scripts/install-btrfs.sh

@@ -2,7 +2,7 @@
 set -euo pipefail
 
 # Non-interactive Btrfs installer using disko-install.
-# Defaults: DISK=/dev/vda TARGET_HOST=nanuqsaurus
+# Defaults: DISK=/dev/vda TARGET_HOST=nanuqsaurus-btrfs
 # If FLAKE is unset and /etc/nixos/flake.nix exists, it uses /etc/nixos.
 # Otherwise, set FLAKE to a flake URI like:
 #   - git+https://codeberg.org/<owner>/<repo>.git

templates/home-flake.nix

@@ -1,5 +1,5 @@
 {
-    description = "Home Manager configuration of admin";
+    description = "Home Manager configuration of @ADMIN_USER@";
 
     inputs = {
         nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
@@ -13,7 +13,7 @@
     };
 
     outputs = { nixpkgs, home-manager, nix-flatpak, ... }: {
-        homeConfigurations."admin" = home-manager.lib.homeManagerConfiguration {
+        homeConfigurations."@ADMIN_USER@" = home-manager.lib.homeManagerConfiguration {
         pkgs = nixpkgs.legacyPackages.x86_64-linux;
         modules = [
             nix-flatpak.homeManagerModules.nix-flatpak

templates/home-home.nix

@@ -6,8 +6,8 @@
 }:
 
 {
-  home.username = "admin";
+  home.username = "@ADMIN_USER@";
-  home.homeDirectory = "/home/admin";
+  home.homeDirectory = "/home/@ADMIN_USER@";
   home.stateVersion = "25.05";
 
   nixpkgs.config.allowUnfree = true;
@@ -97,7 +97,7 @@
 
       [no-cd]
       switch:
-          home-manager switch --flake ~/.config/home-manager#$USER
+home-manager switch --flake ~/.config/home-manager#$USER
 
       [no-cd]
       rebuild: