terminal: separate basic and full LND client setup

In the upcoming actions migration, we will need to fetch LND's macaroons
prior creating litd's stores, and therefore we need to connect to LND
prior to creating the stores.

To avoid having to wait for LND to fully sync before creating the stores
(and, by extension, Litd's RPC servers), we separate the basic LND
client setup from the full LND client setup. Only the full setup
requires a fully synced LND.

Author: ViktorT-11

terminal.go

@@ -695,11 +695,16 @@ func (g *LightningTerminal) start(ctx context.Context) error {
 		}
 	}
 
-	// Set up all the LND clients required by LiT.
-	err = g.setUpLNDClients(ctx, lndQuit)
+	// Since we are now connected to LND, we can now set up a basic LND
+	// client. Note this doesn't require LND to be synced, but can still be
+	// used to fetch info from LND such as its macaroons. Therefore, it's ok
+	// set it up prior to setting up the stores and starting the other RPC
+	// servers, as the setup will be fast.
+	err = g.setupBasicLNDClient(ctx, lndQuit)
 	if err != nil {
 		g.statusMgr.SetErrored(
-			subservers.LND, "could not set up LND clients: %v", err,
+			subservers.LND,
+			"could not to set up a basic LND client: %v", err,
 		)
 
 		return fmt.Errorf("could not start LND")
@@ -776,6 +781,18 @@ func (g *LightningTerminal) start(ctx context.Context) error {
 		return fmt.Errorf("could not register RPC servers: %v", err)
 	}
 
+	// Set up a full LND client. With this, we now have all LND clients
+	// needed for LiT to be fully started.
+	err = g.setupFullNDClient(ctx, lndQuit)
+	if err != nil {
+		g.statusMgr.SetErrored(
+			subservers.LND,
+			"could not to set up a full LND client: %v", err,
+		)
+
+		return fmt.Errorf("could not start LND")
+	}
+
 	// Mark that lnd is now completely running after connecting the
 	// lnd clients.
 	g.statusMgr.SetRunning(subservers.LND)
@@ -826,13 +843,35 @@ func (g *LightningTerminal) basicLNDClient() (lnrpc.LightningClient, error) {
 	return g.basicClient, nil
 }
 
-// setUpLNDClients sets up the various LND clients required by LiT.
-func (g *LightningTerminal) setUpLNDClients(ctx context.Context,
+// checkRunning checks if we should continue running for the duration of the
+// defaultStartupTimeout, or else returns an error indicating why a shut-down is
+// needed.
+func (g *LightningTerminal) checkRunning(ctx context.Context,
+	lndQuit chan struct{}) error {
+
+	select {
+	case err := <-g.errQueue.ChanOut():
+		return fmt.Errorf("error from subsystem: %v", err)
+
+	case <-lndQuit:
+		return fmt.Errorf("LND has stopped")
+
+	case <-ctx.Done():
+		return ctx.Err()
+
+	case <-time.After(g.cfg.LndConnectInterval):
+		return nil
+	}
+}
+
+// setupBasicLNDClient sets up a basic LND client that can be used to connect to
+// LND without requiring LND to be fully synced. Since this client is only a
+// basic client, not all of LNDs functionality is available through it.
+func (g *LightningTerminal) setupBasicLNDClient(ctx context.Context,
 	lndQuit chan struct{}) error {
 
 	var (
 		err           error
-		insecure      bool
 		clientOptions []lndclient.BasicClientOption
 	)
 
@@ -847,36 +886,13 @@ func (g *LightningTerminal) setUpLNDClients(ctx context.Context,
 	// If we're in integrated mode, we can retrieve the macaroon string
 	// from lnd directly, rather than grabbing it from disk.
 	if g.cfg.LndMode == ModeIntegrated {
-		// Set to true in integrated mode, since we will not require tls
-		// when communicating with lnd via a bufconn.
-		insecure = true
 		clientOptions = append(clientOptions, lndclient.Insecure())
 	}
 
-	// checkRunning checks if we should continue running for the duration of
-	// the defaultStartupTimeout, or else returns an error indicating why
-	// a shut-down is needed.
-	checkRunning := func() error {
-		select {
-		case err := <-g.errQueue.ChanOut():
-			return fmt.Errorf("error from subsystem: %v", err)
-
-		case <-lndQuit:
-			return fmt.Errorf("LND has stopped")
-
-		case <-ctx.Done():
-			return ctx.Err()
-
-		case <-time.After(g.cfg.LndConnectInterval):
-			return nil
-		}
-	}
-
 	// The main RPC listener of lnd might need some time to start, it could
 	// be that we run into a connection refused a few times. We use the
 	// basic client connection to find out if the RPC server is started yet
-	// because that doesn't do anything else than just connect. We'll check
-	// if lnd is also ready to be used in the next step.
+	// because that doesn't do anything else than just connect.
 	log.Infof("Connecting basic lnd client")
 
 	for {
@@ -898,7 +914,7 @@ func (g *LightningTerminal) setUpLNDClients(ctx context.Context,
 			"Error when setting up basic LND Client: %v", err,
 		)
 
-		err = checkRunning()
+		err = g.checkRunning(ctx, lndQuit)
 		if err != nil {
 			return err
 		}
@@ -921,12 +937,34 @@ func (g *LightningTerminal) setUpLNDClients(ctx context.Context,
 		g.cfg.statelessInitMode = macService.StatelessInit
 	}
 
-	// Now we know that the connection itself is ready. But we also need to
-	// wait for two things: The chain notifier to be ready and the lnd
-	// wallet being fully synced to its chain backend. The chain notifier
-	// will always be ready first so if we instruct the lndclient to wait
-	// for the wallet sync, we should be fully ready to start all our
-	// subservers. This will just block until lnd signals readiness.
+	return nil
+}
+
+// setupFullNDClient connects a up a full LND client to LND. Note that the setup
+// of this client will block until LND is fully synced and unlocked.
+func (g *LightningTerminal) setupFullNDClient(ctx context.Context,
+	lndQuit chan struct{}) error {
+
+	var (
+		err      error
+		insecure bool
+	)
+
+	host, network, tlsPath, macPath, macData := g.cfg.lndConnectParams()
+
+	if g.cfg.LndMode == ModeIntegrated {
+		// Ssince we will not require tls when communicating with lnd
+		// via a bufconn in integrated mode, we set the insecure flag
+		// to true.
+		insecure = true
+	}
+
+	// When setting up a full LND client, we we need to wait for two things:
+	// The chain notifier to be ready and the lnd wallet being fully synced
+	// to its chain backend. The chain notifier will always be ready first
+	// so if we instruct the lndclient to wait for the wallet sync, we
+	// should be fully ready to start all our subservers. This will just
+	// block until lnd signals readiness.
 	log.Infof("Connecting full lnd client")
 	for {
 		g.lndClient, err = lndclient.NewLndServices(
@@ -959,7 +997,7 @@ func (g *LightningTerminal) setUpLNDClients(ctx context.Context,
 			err,
 		)
 
-		err = checkRunning()
+		err = g.checkRunning(ctx, lndQuit)
 		if err != nil {
 			return err
 		}