MailSend/scripts/prepare-dovecot.sh

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

project_dir="${MAILHUB_PROJECT_DIR:-$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd -P)}"
data_dir="${MAILHUB_DATA_DIR:-${project_dir}/data}"

fail() {
  echo "Dovecot preparation failed: $*" >&2
  exit 1
}

command -v openssl >/dev/null 2>&1 || fail "openssl is required."
[[ ! -L "${data_dir}" ]] || fail "data directory must not be a symbolic link."
mkdir -p "${data_dir}"
data_dir="$(cd "${data_dir}" && pwd -P)"
secret_file="${MAILHUB_DOVECOT_SECRET_FILE:-${data_dir}/secrets/dovecot_auth_secret}"
maildir_root="${MAILHUB_MAILDIR_ROOT:-${data_dir}/maildir}"
host_uid="$(id -u)"

if [[ "$(uname -s)" == "Linux" && "${host_uid}" != "0" && "${host_uid}" != "1000" ]]; then
  fail "Linux preparation must run as root or host uid 1000 so the rootless containers can read and write their bind mounts."
fi

case "${secret_file}" in
  "${data_dir}"/*) ;;
  *) fail "secret file must stay inside the MailHub data directory." ;;
esac
case "${maildir_root}" in
  "${data_dir}"/*) ;;
  *) fail "Maildir root must stay inside the MailHub data directory." ;;
esac

[[ ! -L "${secret_file}" ]] || fail "secret file must not be a symbolic link."
[[ ! -L "${maildir_root}" ]] || fail "Maildir root must not be a symbolic link."
mkdir -p "$(dirname "${secret_file}")" "${maildir_root}"

if [[ ! -f "${secret_file}" ]]; then
  umask 077
  temporary_secret="$(mktemp "$(dirname "${secret_file}")/.dovecot-auth.XXXXXX")"
  trap 'rm -f -- "${temporary_secret:-}"' EXIT
  openssl rand -hex 32 >"${temporary_secret}"
  chmod 0600 "${temporary_secret}"
  mv "${temporary_secret}" "${secret_file}"
  trap - EXIT
fi

[[ -f "${secret_file}" ]] || fail "secret path must be a regular file."
secret="$(tr -d '\r\n' <"${secret_file}")"
[[ "${secret}" =~ ^[0-9a-fA-F]+$ ]] || fail "secret must contain only hexadecimal characters."
(( ${#secret} >= 64 && ${#secret} <= 512 )) || fail "secret must contain 64-512 hexadecimal characters."

if [[ "${host_uid}" == "0" ]]; then
  # Both the Node application and Dovecot's rootless mail processes use
  # uid/gid 1000. Compose file-backed secrets preserve host ownership on Linux.
  chown 1000:1000 "${secret_file}" "${maildir_root}"
fi
chmod 0700 "${maildir_root}"
chmod 0400 "${secret_file}"

echo "Dovecot storage and authentication secret are ready."