disko/disko-install

#!/usr/bin/env bash

set -euo pipefail

showUsage() {
  cat <<EOF
Usage: $0 [OPTIONS]
  -f, --flake FLAKE_URI#ATTR  Use the specified flake to install the NixOS configuration.
  --dry-run                   Print the commands that would be run, but do not run them.
  --show-trace                Show the stack trace on error.
  -h, --help                  Show this help message.
  --reference-lock-file FILE  Use the specified lock file as a reference for the Nix store.
  --write-efi-boot-entries    Write EFI boot entries to the NVRAM of the system for the installed system.
                              Specify this option if you plan to boot from this disk on the current machine,
                              but not if you plan to move the disk to another machine.
EOF
}

serialiaseArrayToNix() {
  local -n array=$1
  nixExpr="{ "
  # Iterate over the associative array to populate the Nix attrset string
  for key in "${!array[@]}"; do
    value=${array[$key]}
    nixExpr+="\"${key//\"/\\\"}\" = \"${value//\"/\\\"}\"; "
  done
  nixExpr+="}"

  echo "$nixExpr"
}

readonly libexec_dir="${0%/*}"

nix_args=(
  --extra-experimental-features 'nix-command flakes'
  "--option" "no-write-lock-file" "true"
)
dry_run=
diskoAttr=diskoScript
writeEfiBootEntries=false
declare -A diskMappings

parseArgs() {
  [[ $# -eq 0 ]] && {
    showUsage
    exit 1
  }

  while [[ $# -gt 0 ]]; do
    case "$1" in
    -d | --debug)
      set -x
      ;;
    -f | --flake)
      flake=$2
      shift
      ;;
    -h | --help)
      showUsage
      exit 0
      ;;
    --dry-run)
      dry_run=y
      ;;
    --show-trace)
      nix_args+=("$1")
      ;;
    --write-efi-boot-entries)
      writeEfiBootEntries=true
      ;;
    --mode)
      if [[ $# -lt 2 ]]; then
        echo "Option $1 requires an argument" >&2
        exit 1
      fi
      case $2 in
        format)
          diskoAttr=diskoScript
          ;;
        mount)
          diskoAttr=mountScript
          ;;
        *)
          echo "Invalid mode: $2" >&2
          echo "Valid modes are: format, mount" >&2
          exit 1
          ;;
      esac
      mode=$2
      shift
      ;;
    --option)
      if [[ $# -lt 3 ]]; then
        echo "Option $1 requires an argument" >&2
        exit 1
      fi
      nix_args+=(--option "$2" "$3")
      shift
      shift
      ;;
    --disk)
      if [[ $# -lt 3 ]]; then
        echo "Option $1 requires an argument" >&2
        exit 1
      fi
      # shellcheck disable=SC2034
      diskMappings[$2]=$3
      shift
      shift
      ;;
    *)
      echo "Unknown option: $1" >&2
      showUsage
      exit 1
      ;;
    esac
    shift
  done
}

cleanupMountPoint() {
  mountPoint=$1
  if mountpoint -q "${mountPoint}"; then
    umount -R "${mountPoint}"
  fi
  rmdir "${mountPoint}"
}

main() {
  parseArgs "$@"

  if [[ -z ${flake-} ]]; then
    echo "Please specify the flake-uri with --flake to use for installation." >&2
    exit 1
  fi

  if [[ $flake =~ ^(.*)\#([^\#\"]*)$ ]]; then
    flake="${BASH_REMATCH[1]}"
    flakeAttr="${BASH_REMATCH[2]}"
  fi
  if [[ -z ${flakeAttr-} ]]; then
    echo "Please specify the name of the NixOS configuration to be installed, as a URI fragment in the flake-uri." >&2
    echo 'For example, to use the output nixosConfigurations.foo from the flake.nix, append "#foo" to the flake-uri.' >&2
    exit 1
  fi

  mountPoint=$(mktemp -d)
  chmod 755 "${mountPoint}" # bchachefs wants 755
  escapeMountPoint=$(printf '%q' "$mountPoint")
  # shellcheck disable=SC2064
  trap "cleanupMountPoint ${escapeMountPoint}" EXIT

  IFS=$'\n' mapfile -t artifacts < <(nix-build "${libexec_dir}"/install-cli.nix \
    "${nix_args[@]}" \
    --no-out-link \
    --impure \
    --argstr flake "$flake" \
    --argstr flakeAttr "$flakeAttr" \
    --argstr rootMountPoint "$mountPoint" \
    --arg writeEfiBootEntries "$writeEfiBootEntries" \
    --arg diskMappings "$(serialiaseArrayToNix diskMappings)" \
    -A installToplevel \
    -A "$diskoAttr")
  nixos_system=${artifacts[0]}
  disko_script=${artifacts[1]}

  if [[ -n ${dry_run-} ]]; then
    echo "Would run: $disko_script"
    echo "Would run: nixos-install --system '$nixos_system' --root '$mountPoint'"
    exit 0
  fi

  "$disko_script"
  nixos-install --no-root-password --system "$nixos_system" --root "$mountPoint"
}

main "$@"