multi: make watchtower client/server DBs remote compatible

The final database that needs to be made remote compatible is the
watchtower server and client database.
They are handled a bit differently because both of them are not always
active, only when specifically turned on in the config.

lncfg/db.go

@@ -10,9 +10,11 @@ import (
 )
 
 const (
-	channelDBName    = "channel.db"
-	macaroonDBName   = "macaroons.db"
-	decayedLogDbName = "sphinxreplay.db"
+	channelDBName     = "channel.db"
+	macaroonDBName    = "macaroons.db"
+	decayedLogDbName  = "sphinxreplay.db"
+	towerClientDBName = "wtclient.db"
+	towerServerDBName = "watchtower.db"
 
 	BoltBackend                = "bolt"
 	EtcdBackend                = "etcd"
@@ -28,6 +30,14 @@ const (
 	// NSDecayedLogDB is the namespace name that we use for the sphinx
 	// replay a.k.a. decayed log DB.
 	NSDecayedLogDB = "decayedlogdb"
+
+	// NSTowerClientDB is the namespace name that we use for the watchtower
+	// client DB.
+	NSTowerClientDB = "towerclientdb"
+
+	// NSTowerServerDB is the namespace name that we use for the watchtower
+	// server DB.
+	NSTowerServerDB = "towerserverdb"
 )
 
 // DB holds database configuration for LND.
@@ -117,6 +127,14 @@ type DatabaseBackends struct {
 	// data.
 	DecayedLogDB kvdb.Backend
 
+	// TowerClientDB points to a database backend that stores the watchtower
+	// client data. This might be nil if the watchtower client is disabled.
+	TowerClientDB kvdb.Backend
+
+	// TowerServerDB points to a database backend that stores the watchtower
+	// server data. This might be nil if the watchtower server is disabled.
+	TowerServerDB kvdb.Backend
+
 	// Remote indicates whether the database backends are remote, possibly
 	// replicated instances or local bbolt backed databases.
 	Remote bool
@@ -128,7 +146,8 @@ type DatabaseBackends struct {
 
 // GetBackends returns a set of kvdb.Backends as set in the DB config.
 func (db *DB) GetBackends(ctx context.Context, chanDBPath,
-	walletDBPath string) (*DatabaseBackends, error) {
+	walletDBPath, towerServerDBPath string, towerClientEnabled,
+	towerServerEnabled bool) (*DatabaseBackends, error) {
 
 	// We keep track of all the kvdb backends we actually open and return a
 	// reference to their close function so they can be cleaned up properly
@@ -159,13 +178,15 @@ func (db *DB) GetBackends(ctx context.Context, chanDBPath,
 
 		returnEarly = false
 		return &DatabaseBackends{
-			GraphDB:      etcdBackend,
-			ChanStateDB:  etcdBackend,
-			HeightHintDB: etcdBackend,
-			MacaroonDB:   etcdBackend,
-			DecayedLogDB: etcdBackend,
-			Remote:       true,
-			CloseFuncs:   closeFuncs,
+			GraphDB:       etcdBackend,
+			ChanStateDB:   etcdBackend,
+			HeightHintDB:  etcdBackend,
+			MacaroonDB:    etcdBackend,
+			DecayedLogDB:  etcdBackend,
+			TowerClientDB: etcdBackend,
+			TowerServerDB: etcdBackend,
+			Remote:        true,
+			CloseFuncs:    closeFuncs,
 		}, nil
 	}
 
@@ -209,14 +230,58 @@ func (db *DB) GetBackends(ctx context.Context, chanDBPath,
 	}
 	closeFuncs[NSDecayedLogDB] = decayedLogBackend.Close
 
+	// The tower client is optional and might not be enabled by the user. We
+	// handle it being nil properly in the main server.
+	var towerClientBackend kvdb.Backend
+	if towerClientEnabled {
+		towerClientBackend, err = kvdb.GetBoltBackend(
+			&kvdb.BoltBackendConfig{
+				DBPath:            chanDBPath,
+				DBFileName:        towerClientDBName,
+				DBTimeout:         db.Bolt.DBTimeout,
+				NoFreelistSync:    !db.Bolt.SyncFreelist,
+				AutoCompact:       db.Bolt.AutoCompact,
+				AutoCompactMinAge: db.Bolt.AutoCompactMinAge,
+			},
+		)
+		if err != nil {
+			return nil, fmt.Errorf("error opening tower client "+
+				"DB: %v", err)
+		}
+		closeFuncs[NSTowerClientDB] = towerClientBackend.Close
+	}
+
+	// The tower server is optional and might not be enabled by the user. We
+	// handle it being nil properly in the main server.
+	var towerServerBackend kvdb.Backend
+	if towerServerEnabled {
+		towerServerBackend, err = kvdb.GetBoltBackend(
+			&kvdb.BoltBackendConfig{
+				DBPath:            towerServerDBPath,
+				DBFileName:        towerServerDBName,
+				DBTimeout:         db.Bolt.DBTimeout,
+				NoFreelistSync:    !db.Bolt.SyncFreelist,
+				AutoCompact:       db.Bolt.AutoCompact,
+				AutoCompactMinAge: db.Bolt.AutoCompactMinAge,
+			},
+		)
+		if err != nil {
+			return nil, fmt.Errorf("error opening tower server "+
+				"DB: %v", err)
+		}
+		closeFuncs[NSTowerServerDB] = towerServerBackend.Close
+	}
+
 	returnEarly = false
 	return &DatabaseBackends{
-		GraphDB:      boltBackend,
-		ChanStateDB:  boltBackend,
-		HeightHintDB: boltBackend,
-		MacaroonDB:   macaroonBackend,
-		DecayedLogDB: decayedLogBackend,
-		CloseFuncs:   closeFuncs,
+		GraphDB:       boltBackend,
+		ChanStateDB:   boltBackend,
+		HeightHintDB:  boltBackend,
+		MacaroonDB:    macaroonBackend,
+		DecayedLogDB:  decayedLogBackend,
+		TowerClientDB: towerClientBackend,
+		TowerServerDB: towerServerBackend,
+		CloseFuncs:    closeFuncs,
 	}, nil
 }