In our environment processes run in isolated process namespaces and cannot send signals to each other.
We need to implement correct log rotation for envoy, and possible solution is to expose /reopen_logs admin handler which triggers AccessLogManager's reopen() similar to SIGUSR1 handler.

Implementation might be pretty straightforward:

Http::Code AdminImpl::handlerReopenLogs(absl::string_view, Http::HeaderMap&,
                                          Buffer::Instance& response, AdminStream&) {
  server_.accessLogManager().reopen();
  response.add("OK\n");
  return Http::Code::OK;
}