code: func (wfe *WebFrontEndImpl) BuildID(ctx context.Context, logEvent *web.RequestEvent, response http.ResponseWriter, request *http.Request) {
  	response.Header().Set("Content-Type", "text/plain")
  	response.WriteHeader(http.StatusOK)
  	detailsString := fmt.Sprintf("Boulder=(%s %s)", core.GetBuildID(), core.GetBuildTime())
  	if _, err := fmt.Fprintln(response, detailsString); err != nil {
  		wfe.log.Warningf("Could not write response: %s", err)
  	}
  }
docs: // BuildID tells the requestor what build we're running.