ensure online status and route changes are propagated (#1564)

hscontrol/derp/server/derp_server.go

@@ -18,6 +18,7 @@ import (
 	"tailscale.com/net/stun"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/key"
+	"tailscale.com/types/logger"
 )
 
 // fastStartHeader is the header (with value "1") that signals to the HTTP
@@ -33,13 +34,19 @@ type DERPServer struct {
 	tailscaleDERP *derp.Server
 }
 
+func derpLogf() logger.Logf {
+	return func(format string, args ...any) {
+		log.Debug().Caller().Msgf(format, args...)
+	}
+}
+
 func NewDERPServer(
 	serverURL string,
 	derpKey key.NodePrivate,
 	cfg *types.DERPConfig,
 ) (*DERPServer, error) {
 	log.Trace().Caller().Msg("Creating new embedded DERP server")
-	server := derp.NewServer(derpKey, log.Debug().Msgf) // nolint // zerolinter complains
+	server := derp.NewServer(derpKey, derpLogf()) // nolint // zerolinter complains
 
 	return &DERPServer{
 		serverURL:     serverURL,