make-image

#!/usr/bin/env bash

function do_it () {
  set -xe
  local ALPINE_VERSION
  local __TARGET_HOSTNAME
  local __DEVICE_NAME
  local __ROOT_PASSWORD
  local __TLD
  local __USERNAME
  local __PASSWORD
  local __LOCALE
  local __TIMEZONE
  local __DNS_SERVER
  local __DNS_DOMAIN

  local OUTPUT_IMG

  local IMGID
  local BOOT_PARTUUID
  local ROOT_PARTUUID

  local ROOT_PART_START
  local ROOT_BLOCK_SIZE
  local ROOT_MIN_SIZE

  local PART_END
  local FREE_START

  ALPINE_VERSION="v0.13.2"
  __TARGET_HOSTNAME="${TARGET_HOSTNAME:-raspberrypi}"
  __DEVICE_NAME="${DEVICE_NAME:-sda}"
  __ROOT_PASSWORD="${ROOT_PASSWORD:-raspberry}"
  __TLD="${TLD:-lan}"
  __USERNAME="${USERNAME:-pi}"
  __PASSWORD="${PASSWORD:-raspberry}"
  __LOCALE="${LOCALE:-us-us}"
  __TIMEZONE="${TIMEZONE:-UTC}"
  # shellcheck disable=SC2153
  __DNS_SERVER="${DNS_SERVER}"
  # shellcheck disable=SC2153
  __DNS_DOMAIN="${DNS_DOMAIN}"

  OUTPUT_IMG="/dist/target.img"

  mkdir -p dist /dist

  rm -Rf "${OUTPUT_IMG}"
  truncate -s 2G "${OUTPUT_IMG}"

  fdisk -H 255 -S 63 "${OUTPUT_IMG}" <<-EOF
o
n
p
1

+128MB
t
c
n
p
2


w
EOF

  LOOP_DEV=$(losetup --partscan --show --find "${OUTPUT_IMG}")
  BOOT_DEV="${LOOP_DEV}"p1
  ROOT_DEV="${LOOP_DEV}"p2

  # format partitions
  mkfs.fat -F32 -n ALPINE "${BOOT_DEV}"
  mkfs.ext4 "${ROOT_DEV}"
  mkdir -p /alpine
  mount --make-private "${ROOT_DEV}" /alpine
  mkdir -p /alpine/boot
  mount --make-private "${BOOT_DEV}" /alpine/boot

  IMGID="$(dd if="${OUTPUT_IMG}" skip=440 bs=1 count=4 2>/dev/null | xxd -e | cut -f 2 -d' ')"

  BOOT_PARTUUID="${IMGID}-01"
  ROOT_PARTUUID="${IMGID}-02"

  echo "boot partition uuid: ${BOOT_PARTUUID}"
  echo "root partition uuid: ${ROOT_PARTUUID}"

  apt-get update
  curl https://raw.githubusercontent.com/alpinelinux/alpine-chroot-install/${ALPINE_VERSION}/alpine-chroot-install | sh

  cp -R bootstrap/ /alpine/

  /alpine/enter-chroot /bootstrap/00-environment.sh
  /alpine/enter-chroot /bootstrap/01-kernel.sh "${__DEVICE_NAME}"
  /alpine/enter-chroot /bootstrap/02-system.sh "${__TARGET_HOSTNAME}" "${__ROOT_PASSWORD}" "${__TLD}" "${__DEVICE_NAME}" "${__LOCALE}" "${__TIMEZONE}" "${__DNS_SERVER}" "${__DNS_DOMAIN}"
  /alpine/enter-chroot /bootstrap/03-users.sh "${__USERNAME}" "${__PASSWORD}"
  /alpine/enter-chroot /bootstrap/04-networking.sh "${__TARGET_HOSTNAME}"
  /alpine/enter-chroot /bootstrap/05-services.sh
  /alpine/enter-chroot /bootstrap/06-first-boot.sh "${__DEVICE_NAME}"

  rm -rf /alpine/var/lib/apt/lists/*
  rm -rf /alpine/var/cache/apk/*
  rm -rf /alpine/root/*
  rm -rf /alpine/bootstrap/

  rm -rf /alpine/destroy /alpine/enter-chroot /alpine/etc/resolv.conf /alpine/env.sh
  find /alpine -iname "*-" -delete
  find /alpine -iname "*~" -delete

  umount -lf /alpine

  # shrink image
  ROOT_PART_START=$(parted -ms "${OUTPUT_IMG}" unit B print | tail -n 1 | cut -d ':' -f 2 | tr -d 'B')
  ROOT_BLOCK_SIZE=$(tune2fs -l "${ROOT_DEV}" | grep '^Block size:' | tr -d ' ' | cut -d ':' -f 2)
  ROOT_MIN_SIZE=$(resize2fs -P "${ROOT_DEV}" | cut -d ':' -f 2 | tr -d ' ')

  # shrink fs
  e2fsck -f -p "${ROOT_DEV}"
  resize2fs -p "${ROOT_DEV}" "${ROOT_MIN_SIZE}"

  # shrink partition
  PART_END=$((ROOT_PART_START + (ROOT_MIN_SIZE * ROOT_BLOCK_SIZE)))
  parted ---pretend-input-tty "$OUTPUT_IMG" <<EOF
unit B
resizepart 2 ${PART_END}
yes
quit
EOF

  losetup -d "${LOOP_DEV}"

  # truncate free space
  FREE_START=$(parted -ms "${OUTPUT_IMG}" unit B print free | tail -1 | cut -d ':' -f 2 | tr -d 'B')
  truncate -s "${FREE_START}" "${OUTPUT_IMG}"

  cp ${OUTPUT_IMG} "dist/alpine-rpi-${ALPINE_BRANCH}-${ARCH}.img"
  #gzip -c "$OUTPUT_IMG" > "dist/alpine-rpi-${ALPINE_BRANCH}-${ARCH}.img.gz"

  echo "DONE."
}

do_it "$@"