'stun' has been removed from metric names and replaced with a protocol
label. This refactor is preparation work for HTTPS & ICMP support.
Updates tailscale/corp#22114
Signed-off-by: Jordan Whited <jordan@tailscale.com>
stunstamp timestamping includes userspace and SO_TIMESTAMPING kernel
timestamping where available. Measurements are written locally to a
sqlite DB, exposed over an HTTP API, and written to prometheus
via remote-write protocol.
Updates tailscale/corp#20344
Signed-off-by: Jordan Whited <jordan@tailscale.com>
