# Ntfy relay

The ntfy relay runs on `notify-host-1` and fans alert payloads out to the
phones and the desktop notifier.

- Topic namespaces are per host, so a host can only publish into its own.
- Retention is twelve hours; anything older is dropped on the sweep.
- The access log lives at `/var/log/ntfy/access.log` and rotates weekly.
- SMTP fallback is disabled on purpose: a failed push is a signal, not
  something to paper over with an email.
- The relay is fronted by the proxy on 443 with mutual TLS for publishers.

Publishing is a plain POST with the topic in the path. The relay stamps a
monotonic sequence number so a subscriber can detect a gap after a
reconnect, and the gap detection is what the shelf watchdog polls.