path: root/.gitlab/ci/build_archiso.sh

#!/usr/bin/env bash
#
# This script is run within a virtual environment to build the available archiso profiles and their available build
# modes and create checksum files for the resulting images.
# The script needs to be run as root and assumes $PWD to be the root of the repository.
#
# Dependencies:
# * all archiso dependencies
# * coreutils
# * gnupg
# * openssl
# * zsync
#
# $1: profile
# $2: buildmode

set -euo pipefail
shopt -s extglob

readonly orig_pwd="${PWD}"
readonly output="${orig_pwd}/output"
readonly tmpdir_base="${orig_pwd}/tmp"
readonly profile="${1}"
readonly buildmode="${2}"
readonly install_dir="arch"

tmpdir=""
tmpdir="$(mktemp --dry-run --directory --tmpdir="${tmpdir_base}")"
gnupg_homedir=""
codesigning_dir=""
codesigning_cert=""
codesigning_key=""
ca_cert=""
ca_key=""
pgp_key_id=""

print_section_start() {
  # gitlab collapsible sections start: https://docs.gitlab.com/ee/ci/jobs/#custom-collapsible-sections
  local _section _title
  _section="${1}"
  _title="${2}"

  printf "\e[0Ksection_start:%(%s)T:%s\r\e[0K%s\n" '-1' "${_section}" "${_title}"
}

print_section_end() {
  # gitlab collapsible sections end: https://docs.gitlab.com/ee/ci/jobs/#custom-collapsible-sections
  local _section
  _section="${1}"

  printf "\e[0Ksection_end:%(%s)T:%s\r\e[0K\n" '-1' "${_section}"
}

cleanup() {
  # clean up temporary directories
  print_section_start "cleanup" "Cleaning up temporary directory"

  if [ -n "${tmpdir_base:-}" ]; then
    rm -fr "${tmpdir_base}"
  fi

  print_section_end "cleanup"
}

create_checksums() {
  # create checksums for files
  # $@: files
  local _file_path _file_name _current_pwd
  _current_pwd="${PWD}"

  print_section_start "checksums" "Creating checksums"

  for _file_path in "$@"; do
    cd "$(dirname "${_file_path}")"
    _file_name="$(basename "${_file_path}")"
    b2sum "${_file_name}" > "${_file_name}.b2"
    md5sum "${_file_name}" > "${_file_name}.md5"
    sha1sum "${_file_name}" > "${_file_name}.sha1"
    sha256sum "${_file_name}" > "${_file_name}.sha256"
    sha512sum "${_file_name}" > "${_file_name}.sha512"
    ls -lah "${_file_name}."{b2,md5,sha{1,256,512}}
    cat "${_file_name}."{b2,md5,sha{1,256,512}}
  done
  cd "${_current_pwd}"

  print_section_end "checksums"
}

create_zsync_delta() {
  # create zsync control files for files
  # $@: files
  local _file

  print_section_start "zsync_delta" "Creating zsync delta"

  for _file in "$@"; do
    if [[ "${buildmode}" == "bootstrap" ]]; then
      # zsyncmake fails on 'too long between blocks' with default block size on bootstrap image
      zsyncmake -v -b 512 -C -u "${_file##*/}" -o "${_file}".zsync "${_file}"
    else
      zsyncmake -v -C -u "${_file##*/}" -o "${_file}".zsync "${_file}"
    fi
  done

  print_section_end "zsync_delta"
}

create_metrics() {
  local _metrics="${output}/metrics.txt"
  # create metrics
  print_section_start "metrics" "Creating metrics"

  {
    # create metrics based on buildmode
    case "${buildmode}" in
      iso)
        printf 'image_size_mebibytes{image="%s"} %s\n' \
          "${profile}" \
          "$(du -m -- "${output}/"*.iso | cut -f1)"
        printf 'package_count{image="%s"} %s\n' \
          "${profile}" \
          "$(sort -u -- "${tmpdir}/iso/"*/pkglist.*.txt | wc -l)"
        if [[ -e "${tmpdir}/efiboot.img" ]]; then
          printf 'eltorito_efi_image_size_mebibytes{image="%s"} %s\n' \
            "${profile}" \
            "$(du -m -- "${tmpdir}/efiboot.img" | cut -f1)"
        fi
        # shellcheck disable=SC2046
        # shellcheck disable=SC2183
        printf 'initramfs_size_mebibytes{image="%s",initramfs="%s"} %s\n' \
          $(du -m -- "${tmpdir}/iso/"*/boot/**/initramfs*.img | \
            awk -v profile="${profile}" \
            'function basename(file) {
              sub(".*/", "", file)
              return file
            }
            { print profile, basename($2), $1 }'
          )
        ;;
      netboot)
        printf 'netboot_size_mebibytes{image="%s"} %s\n' \
          "${profile}" \
          "$(du -m -- "${output}/${install_dir}/" | tail -n1 | cut -f1)"
        printf 'netboot_package_count{image="%s"} %s\n' \
          "${profile}" \
          "$(sort -u -- "${tmpdir}/iso/"*/pkglist.*.txt | wc -l)"
        ;;
      bootstrap)
        printf 'bootstrap_size_mebibytes{image="%s"} %s\n' \
          "${profile}" \
          "$(du -m -- "${output}/"*.tar*(.gz|.xz|.zst) | cut -f1)"
        printf 'bootstrap_package_count{image="%s"} %s\n' \
          "${profile}" \
          "$(sort -u -- "${tmpdir}/"*/bootstrap/root.*/pkglist.*.txt | wc -l)"
        ;;
    esac
  } > "${_metrics}"
  ls -lah "${_metrics}"
  cat "${_metrics}"

  print_section_end "metrics"
}

create_ephemeral_pgp_key() {
  # create an ephemeral PGP key for signing the rootfs image
  print_section_start "ephemeral_pgp_key" "Creating ephemeral PGP key"

  gnupg_homedir="$tmpdir/.gnupg"
  mkdir -p "${gnupg_homedir}"
  chmod 700 "${gnupg_homedir}"

  cat << __EOF__ > "${gnupg_homedir}"/gpg.conf
quiet
batch
no-tty
no-permission-warning
export-options no-export-attributes,export-clean
list-options no-show-keyring
armor
no-emit-version
__EOF__

  gpg --homedir "${gnupg_homedir}" --gen-key <<EOF
%echo Generating ephemeral Arch Linux release engineering key pair...
Key-Type: default
Key-Length: 3072
Key-Usage: sign
Name-Real: Arch Linux Release Engineering
Name-Comment: Ephemeral Signing Key
Name-Email: arch-releng@lists.archlinux.org
Expire-Date: 0
%no-protection
%commit
%echo Done
EOF

  pgp_key_id="$(
    gpg --homedir "${gnupg_homedir}" \
        --list-secret-keys \
        --with-colons \
        | awk -F':' '{if($1 ~ /sec/){ print $5 }}'
  )"

  pgp_sender="Arch Linux Release Engineering (Ephemeral Signing Key) <arch-releng@lists.archlinux.org>"

  print_section_end "ephemeral_pgp_key"
}

create_ephemeral_codesigning_keys() {
  # create ephemeral certificates used for codesigning
  print_section_start "ephemeral_codesigning_key" "Creating ephemeral codesigning keys"

  # The exact steps in creating a CA with Codesigning being signed was taken from
  # https://jamielinux.com/docs/openssl-certificate-authority/introduction.html
  # (slight modifications to the process to not disturb default values of /etc/ssl/openssl.cnf)
  
  codesigning_dir="${tmpdir}/.codesigning/"
  local ca_dir="${codesigning_dir}/ca/"

  local ca_conf="${ca_dir}/certificate_authority.cnf"
  local ca_subj="/C=DE/ST=Berlin/L=Berlin/O=Arch Linux/OU=Release Engineering/CN=archlinux.org"
  ca_cert="${ca_dir}/cacert.pem"
  ca_key="${ca_dir}/private/cakey.pem"

  local codesigning_conf="${codesigning_dir}/code_signing.cnf"
  local codesigning_subj="/C=DE/ST=Berlin/L=Berlin/O=Arch Linux/OU=Release Engineering/CN=archlinux.org"
  codesigning_cert="${codesigning_dir}/codesign.crt"
  codesigning_key="${codesigning_dir}/codesign.key"

  mkdir -p "${ca_dir}/"{private,newcerts,crl}
  mkdir -p "${codesigning_dir}"
  cp -- /etc/ssl/openssl.cnf "${codesigning_conf}"
  cp -- /etc/ssl/openssl.cnf "${ca_conf}"
  touch "${ca_dir}/index.txt"
  echo "1000" > "${ca_dir}/serial"

  # Prepare the ca configuration for the change in directory
  sed -i "s#/etc/ssl#${ca_dir}#g" "${ca_conf}"

  # Create the Certificate Authority
  openssl req \
      -newkey rsa:4096 \
      -sha256 \
      -nodes \
      -x509 \
      -new \
      -sha256 \
      -keyout "${ca_key}" \
      -config "${ca_conf}" \
      -subj "${ca_subj}" \
      -out "${ca_cert}"

  cat << EOF >> "${ca_conf}"

[ v3_intermediate_ca ]
# Extensions for a typical intermediate CA ('man x509v3_config').
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer
basicConstraints = critical, CA:true, pathlen:0
keyUsage = critical, digitalSignature, cRLSign, keyCertSign

EOF

  cat << EOF >> "${codesigning_conf}"

[codesigning]
keyUsage=digitalSignature
extendedKeyUsage=codeSigning, clientAuth, emailProtection

EOF

  openssl req \
      -newkey rsa:4096 \
      -keyout "${codesigning_key}" \
      -nodes \
      -sha256 \
      -out "${codesigning_cert}.csr" \
      -config "${codesigning_conf}" \
      -subj "${codesigning_subj}" \
      -extensions codesigning

  # Sign the code signing certificate with the CA
  openssl ca \
      -batch \
      -config "${ca_conf}" \
      -extensions v3_intermediate_ca \
      -days 3650 \
      -notext \
      -md sha256 \
      -in "${codesigning_cert}.csr" \
      -out "${codesigning_cert}"

  print_section_end "ephemeral_codesigning_key"
}

run_mkarchiso() {
  # run mkarchiso
  create_ephemeral_pgp_key
  create_ephemeral_codesigning_keys

  print_section_start "mkarchiso" "Running mkarchiso"
  mkdir -p "${output}/" "${tmpdir}/"
  GNUPGHOME="${gnupg_homedir}" ./archiso/mkarchiso \
      -D "${install_dir}" \
      -c "${codesigning_cert} ${codesigning_key} ${ca_cert}" \
      -g "${pgp_key_id}" \
      -G "${pgp_sender}" \
      -o "${output}/" \
      -w "${tmpdir}/" \
      -m "${buildmode}" \
      -v "configs/${profile}"

  print_section_end "mkarchiso"

  if [[ "${buildmode}" =~ "iso" ]]; then
    create_zsync_delta "${output}/"*.iso
    create_checksums "${output}/"*.iso
  fi
  if [[ "${buildmode}" == "bootstrap" ]]; then
    create_zsync_delta "${output}/"*.tar*(.gz|.xz|.zst)
    create_checksums "${output}/"*.tar*(.gz|.xz|.zst)
  fi
  create_metrics

  print_section_start "ownership" "Setting ownership on output"

  if [[ -n "${SUDO_UID:-}" ]] && [[ -n "${SUDO_GID:-}" ]]; then
    chown -Rv "${SUDO_UID}:${SUDO_GID}" -- "${output}"
  fi
  print_section_end "ownership"
}

trap cleanup EXIT

run_mkarchiso