subservers: fail LiT startup when integrated sub-server boot fails

* Treat integrated sub-servers as fatal to startup and return an error
if any fail to start.
* Propagate integrated sub-server startup errors to LiT so it stops
launching and records the failure status.
* Update docs to reflect integrated sub-servers are now critical to
startup.

Author: ffranr

subservers/interface.go

@@ -14,9 +14,8 @@ import (
 
 // SubServer defines an interface that should be implemented by any sub-server
 // that the subServer manager should manage. A sub-server can be run in either
-// integrated or remote mode. A sub-server is considered non-fatal to LiT
-// meaning that if a sub-server fails to start, LiT can safely continue with its
-// operations and other sub-servers can too.
+// integrated or remote mode. Integrated sub-servers are treated as critical to
+// LiT startup, meaning a failure to start any of them will abort the process.
 type SubServer interface {
 	macaroons.MacaroonValidator
 

subservers/manager.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"io/ioutil"
+	"strings"
 	"sync"
 	"time"
 
@@ -104,13 +105,16 @@ func (s *Manager) GetServer(name string) (SubServer, bool) {
 }
 
 // StartIntegratedServers starts all the manager's sub-servers that should be
-// started in integrated mode.
+// started in integrated mode. An error is returned if any integrated sub-server
+// fails to start.
 func (s *Manager) StartIntegratedServers(lndClient lnrpc.LightningClient,
-	lndGrpc *lndclient.GrpcLndServices, withMacaroonService bool) {
+	lndGrpc *lndclient.GrpcLndServices, withMacaroonService bool) error {
 
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
+	var errs []string
+
 	for _, ss := range s.servers {
 		if ss.Remote() {
 			continue
@@ -126,11 +130,19 @@ func (s *Manager) StartIntegratedServers(lndClient lnrpc.LightningClient,
 		)
 		if err != nil {
 			s.statusServer.SetErrored(ss.Name(), err.Error())
+			errs = append(errs, fmt.Sprintf("%s: %v", ss.Name(), err))
 			continue
 		}
 
 		s.statusServer.SetRunning(ss.Name())
 	}
+
+	if len(errs) > 0 {
+		return fmt.Errorf("failed starting integrated sub-server(s): %s",
+			strings.Join(errs, "; "))
+	}
+
+	return nil
 }
 
 // ConnectRemoteSubServers creates connections to all the manager's sub-servers

terminal.go

@@ -768,9 +768,18 @@ func (g *LightningTerminal) start(ctx context.Context) error {
 	// Both connection types are ready now, let's start our sub-servers if
 	// they should be started locally as an integrated service.
 	createDefaultMacaroons := !g.cfg.statelessInitMode
-	g.subServerMgr.StartIntegratedServers(
+	err = g.subServerMgr.StartIntegratedServers(
 		g.basicClient, g.lndClient, createDefaultMacaroons,
 	)
+	if err != nil {
+		g.statusMgr.SetErrored(
+			subservers.LIT,
+			"could not start integrated sub-servers: %v", err,
+		)
+
+		return fmt.Errorf("could not start integrated sub-servers: %v",
+			err)
+	}
 
 	err = g.startInternalSubServers(ctx, !g.cfg.statelessInitMode)
 	if err != nil {