Systemd can listen for us and hand over the FD upon service start. This makes the service more restartable as requests aren't lost during the downtime. Restarts during sending are still a problem though as I think the sending stream would get interrupted and upon start not resumed.
https://github.com/coreos/go-systemd
https://github.com/coreos/go-systemd/tree/master/examples/activation/httpserver