move signal server start to server start (#1894)

* move signal server start to server start

* fix test

pkg/service/server.go

@@ -227,6 +227,10 @@ func (s *LivekitServer) Start() error {
 		go s.promServer.Serve(promLn)
 	}
 
+	if err := s.signalServer.Start(); err != nil {
+		return err
+	}
+
 	httpGroup := &errgroup.Group{}
 	for _, ln := range listeners {
 		l := ln

pkg/service/signal.go

@@ -28,6 +28,7 @@ type SessionHandler func(
 
 type SignalServer struct {
 	server rpc.TypedSignalServer
+	nodeID livekit.NodeID
 }
 
 func NewSignalServer(
@@ -47,12 +48,7 @@ func NewSignalServer(
 	if err != nil {
 		return nil, err
 	}
-	logger.Debugw("starting relay signal server", "topic", nodeID)
-	if err := s.RegisterRelaySignalTopic(nodeID); err != nil {
-		return nil, err
-	}
-
-	return &SignalServer{s}, nil
+	return &SignalServer{s, nodeID}, nil
 }
 
 func NewDefaultSignalServer(
@@ -101,6 +97,11 @@ func NewDefaultSignalServer(
 	return NewSignalServer(livekit.NodeID(currentNode.Id), currentNode.Region, bus, config, sessionHandler)
 }
 
+func (s *SignalServer) Start() error {
+	logger.Debugw("starting relay signal server", "topic", s.nodeID)
+	return s.server.RegisterRelaySignalTopic(s.nodeID)
+}
+
 func (r *SignalServer) Stop() {
 	r.server.Kill()
 }

pkg/service/signal_test.go

@@ -44,7 +44,7 @@ func TestSignal(t *testing.T) {
 	client, err := routing.NewSignalClient(livekit.NodeID("node0"), bus, cfg)
 	require.NoError(t, err)
 
-	_, err = NewSignalServer(livekit.NodeID("node1"), "region", bus, cfg, func(
+	server, err := NewSignalServer(livekit.NodeID("node1"), "region", bus, cfg, func(
 		ctx context.Context,
 		roomName livekit.RoomName,
 		pi routing.ParticipantInit,
@@ -62,6 +62,9 @@ func TestSignal(t *testing.T) {
 	})
 	require.NoError(t, err)
 
+	err = server.Start()
+	require.NoError(t, err)
+
 	_, reqSink, resSource, err := client.StartParticipantSignal(
 		context.Background(),
 		livekit.RoomName("room1"),