multi: add default watchtower config to main LND config

In this commit, a `DefaultWatchtowerCfg` function is added which is used
to construct a default `lncfg.Watchtower` struct. This is then used to
populate the default watchtower config in the main LND config struct.

config.go

@@ -638,9 +638,7 @@ func DefaultConfig() Config {
 			ChannelCacheSize: channeldb.DefaultChannelCacheSize,
 		},
 		Prometheus: lncfg.DefaultPrometheus(),
-		Watchtower: &lncfg.Watchtower{
-			TowerDir: defaultTowerDir,
-		},
+		Watchtower: lncfg.DefaultWatchtowerCfg(defaultTowerDir),
 		HealthChecks: &lncfg.HealthCheckConfig{
 			ChainCheck: &lncfg.CheckConfig{
 				Interval: defaultChainInterval,

lncfg/watchtower.go

@@ -13,3 +13,14 @@ type Watchtower struct {
 
 	watchtower.Conf
 }
+
+// DefaultWatchtowerCfg creates a Watchtower with some default values filled
+// out.
+func DefaultWatchtowerCfg(defaultTowerDir string) *Watchtower {
+	conf := watchtower.DefaultConf()
+
+	return &Watchtower{
+		TowerDir: defaultTowerDir,
+		Conf:     *conf,
+	}
+}

watchtower/conf.go

@@ -23,6 +23,14 @@ type Conf struct {
 	WriteTimeout time.Duration `long:"writetimeout" description:"Duration the watchtower server will wait for messages to be written before hanging up on client connections"`
 }
 
+// DefaultConf returns a Conf with some default values filled in.
+func DefaultConf() *Conf {
+	return &Conf{
+		ReadTimeout:  DefaultReadTimeout,
+		WriteTimeout: DefaultWriteTimeout,
+	}
+}
+
 // Apply completes the passed Config struct by applying any parsed Conf options.
 // If the corresponding values parsed by Conf are already set in the Config,
 // those fields will be not be modified.