nanuqsaurus/scripts/install-btrfs.sh

#!/usr/bin/env bash
set -euo pipefail

# Automated Btrfs install using the flake in this repo.
# Defaults remain environment-driven for headless use.
# Interactive prompts are shown unless --non-interactive is set.

NON_INTERACTIVE=0
if [[ "${1:-}" == "--non-interactive" ]]; then
  NON_INTERACTIVE=1
  shift
fi

DISK=${DISK:-/dev/vda}           # full-disk target
ROOT_PART=${ROOT_PART:-}         # optional existing root partition
BOOT_PART=${BOOT_PART:-}         # optional existing boot (FAT) partition
HOSTNAME=${HOSTNAME:-nanuqsaurus}
USE_LUKS=${USE_LUKS:-0}          # 1 to encrypt root
SWAP_GB=${SWAP_GB:-0}            # swap size in GB, 0 disables

SCRIPT_DIR=$(cd -- "$(dirname "${BASH_SOURCE[0]}")" && pwd)
REPO_ROOT=$(cd -- "${SCRIPT_DIR}/.." && pwd)

has_cmd() { command -v "$1" >/dev/null 2>&1; }

prompt_select() {
  local title="$1" prompt="$2" choices=("${@:3}")
  if (( NON_INTERACTIVE )); then
    echo "${choices[0]}"
    return
  fi
  if has_cmd dialog; then
    dialog --no-cancel --menu "$prompt" 15 60 6 "${choices[@]}" 2> /tmp/choice
    cat /tmp/choice
  elif has_cmd whiptail; then
    whiptail --notags --menu "$prompt" 15 60 6 "${choices[@]}" 2> /tmp/choice || true
    cat /tmp/choice
  else
    echo "$prompt"
    select c in "${choices[@]}"; do echo "$c"; break; done
  fi
}

prompt_yes_no() {
  local prompt="$1" default="${2:-n}"
  if (( NON_INTERACTIVE )); then
    [[ "$default" =~ ^[Yy]$ ]] && echo "yes" || echo "no"
    return
  fi
  if has_cmd dialog; then
    if dialog --yesno "$prompt" 8 60; then echo "yes"; else echo "no"; fi
  elif has_cmd whiptail; then
    if whiptail --yesno "$prompt" 8 60; then echo "yes"; else echo "no"; fi
  else
    read -rp "$prompt [y/N]: " ans
    [[ "${ans:-$default}" =~ ^[Yy]$ ]] && echo "yes" || echo "no"
  fi
}

prompt_input() {
  local prompt="$1" default="$2"
  if (( NON_INTERACTIVE )); then
    echo "$default"
    return
  fi
  if has_cmd dialog; then
    dialog --inputbox "$prompt" 8 60 "$default" 2>/tmp/input && cat /tmp/input || echo "$default"
  elif has_cmd whiptail; then
    whiptail --inputbox "$prompt" 8 60 "$default" 2>/tmp/input && cat /tmp/input || echo "$default"
  else
    read -rp "$prompt [$default]: " ans
    echo "${ans:-$default}"
  fi
}

ls_disks() {
  lsblk -dpno NAME,SIZE,TYPE | awk '$3=="disk"{print $1" "$2}'
}

if (( ! NON_INTERACTIVE )); then
  mapfile -t disks < <(ls_disks)
  if ((${#disks[@]})); then
    disk_choices=()
    for d in "${disks[@]}"; do
      disk_choices+=("$d" "")
    done
    DISK=$(prompt_select "disk" "Select target disk (will be wiped)" "${disk_choices[@]}")
  fi

  target_mode=$(prompt_select "mode" "Partitioning mode" \
    "full-disk" "Use entire disk (wipes!)" \
    "existing" "Use existing partitions")

  if [[ "$target_mode" == "existing" ]]; then
    ROOT_PART=$(prompt_input "Root partition (will be formatted btrfs)" "${ROOT_PART:-/dev/vda2}")
    BOOT_PART=$(prompt_input "Boot EFI partition (FAT32)" "${BOOT_PART:-/dev/vda1}")
  fi

  USE_LUKS=$(prompt_yes_no "Encrypt root with LUKS?" "n")
  [[ "$USE_LUKS" == "yes" ]] && USE_LUKS=1 || USE_LUKS=0

  SWAP_GB=$(prompt_input "Swap size in GB (0 = none)" "${SWAP_GB}")
fi

echo "[0/8] Summary:"
echo "  Disk: ${DISK}"
if [[ -n "$ROOT_PART" ]]; then
  echo "  Root partition: $ROOT_PART"
  echo "  Boot partition: $BOOT_PART"
else
  echo "  Mode: full disk wipe"
fi
echo "  LUKS: $([ "$USE_LUKS" -eq 1 ] && echo enabled || echo disabled)"
echo "  Swap: ${SWAP_GB}G"
echo "  Hostname: ${HOSTNAME}"

if (( NON_INTERACTIVE )); then
  echo "Proceeding in non-interactive mode."
else
  if [[ "$(prompt_yes_no "Proceed with these settings? This will destroy data." "n")" != "yes" ]]; then
    echo "Aborted."
    exit 1
  fi
fi

part_boot=""
part_root=""
mapper_root=""

echo "[1/8] Partitioning/selection"
if [[ -z "$ROOT_PART" ]]; then
  printf "label: gpt\n,550M,U,boot\n,,L,cryptroot\n" | sfdisk "${DISK}"
  part_boot="${DISK}1"
  part_root="${DISK}2"
else
  part_boot="${BOOT_PART}"
  part_root="${ROOT_PART}"
fi

echo "[2/8] Formatting boot"
mkfs.fat -F 32 "${part_boot}"

echo "[3/8] Preparing root"
if [[ "$USE_LUKS" -eq 1 ]]; then
  pass=${LUKS_PASSPHRASE:-}
  if [[ -z "$pass" && $NON_INTERACTIVE -eq 0 ]]; then
    pass=$(prompt_input "LUKS passphrase" "")
  fi
  if [[ -z "$pass" ]]; then
    echo "LUKS passphrase required for encrypted install"
    exit 1
  fi
  printf "%s" "$pass" | cryptsetup luksFormat "${part_root}" -
  printf "%s" "$pass" | cryptsetup open "${part_root}" cryptroot -
  mapper_root="/dev/mapper/cryptroot"
else
  mapper_root="${part_root}"
fi

mkfs.btrfs -f "${mapper_root}"

echo "[4/8] Creating Btrfs subvolumes"
mkdir -p /mnt
mount "${mapper_root}" /mnt
btrfs subvolume create /mnt/root
btrfs subvolume create /mnt/home
btrfs subvolume create /mnt/nix
umount /mnt

echo "[5/8] Mounting subvolumes"
mount -o compress=zstd,subvol=root "${mapper_root}" /mnt
mkdir -p /mnt/{home,nix,boot}
mount -o compress=zstd,subvol=home "${mapper_root}" /mnt/home
mount -o compress=zstd,subvol=nix "${mapper_root}" /mnt/nix
mount "${part_boot}" /mnt/boot

if [[ "${SWAP_GB}" -gt 0 ]]; then
  echo "[5b/8] Creating swapfile (${SWAP_GB}G)"
  mkdir -p /mnt/swap
  chattr +C /mnt/swap || true
  fallocate -l "${SWAP_GB}G" /mnt/swap/swapfile
  chmod 600 /mnt/swap/swapfile
  mkswap /mnt/swap/swapfile
  swapon /mnt/swap/swapfile
fi

echo "[6/8] Copying flake to /etc/nixos"
if command -v rsync >/dev/null 2>&1; then
  rsync -a --exclude '.git' --exclude 'result' --exclude 'node_modules' "${REPO_ROOT}/" /mnt/etc/nixos/
else
  (cd "${REPO_ROOT}" && tar -cf - --exclude=.git --exclude=result --exclude=node_modules .) | (cd /mnt/etc/nixos && tar -xf -)
fi

echo "[7/8] Generating hardware config"
hardware_file="/mnt/etc/nixos/hosts/${HOSTNAME}-hardware.nix"
mkdir -p /mnt/etc/nixos/hosts
nixos-generate-config --root /mnt --show-hardware-config > "${hardware_file}"

if [[ "$USE_LUKS" -eq 1 || "${SWAP_GB}" -gt 0 ]]; then
  tmpfile=$(mktemp)
  # drop trailing closing brace
  sed '$d' "${hardware_file}" > "${tmpfile}"
  if [[ "$USE_LUKS" -eq 1 ]]; then
    echo "  boot.initrd.luks.devices.cryptroot.device = \"${part_root}\";" >> "${tmpfile}"
  fi
  if [[ "${SWAP_GB}" -gt 0 ]]; then
    echo "  swapDevices = [ { device = \"/swap/swapfile\"; } ];" >> "${tmpfile}"
  fi
  echo "}" >> "${tmpfile}"
  mv "${tmpfile}" "${hardware_file}"
fi

host_file="/mnt/etc/nixos/hosts/${HOSTNAME}.nix"
if [ ! -e "${host_file}" ]; then
  cat > "${host_file}" <<EOF
{ inputs, ... }:

{
  imports = [
    inputs.lix-module.nixosModules.lixFromNixpkgs
    ../modules/system/base.nix
    ../modules/users/admin.nix
    # Uncomment to enable Secure Boot after install:
    # inputs.lanzaboote.nixosModules.lanzaboote
    # ../modules/system/secure-boot.nix
    ./${HOSTNAME}-hardware.nix
  ];

  networking.hostName = "${HOSTNAME}";
}
EOF
fi

echo "[8/8] Installing ${HOSTNAME} via flake"
nixos-install --root /mnt --flake "/mnt/etc/nixos#${HOSTNAME}"

echo "Install complete. You can reboot now."