else
      echo "No directory at ${ZTUNNEL_DIR}"
      return
    fi
  fi
  if [[ "${BUILD_ZTUNNEL_REPO:-}" == "" ]]; then
    return
  fi

  if ! which cargo; then
    echo "the rust toolchain (cargo, etc) is required for building ztunnel"
    return 1
  fi

  pushd "${BUILD_ZTUNNEL_REPO}"
  cargo build --profile="${BUILD_ZTUNNEL_PROFILE:-dev}" ${BUILD_ZTUNNEL_TARGET:+--target=${BUILD_ZTUNNEL_TARGET}}