lnd: use first key in keychain.KeyFamilyNodeKey as our nodeID

In this commit, we update lnd to now access the deterministic
keychain.KeyRing struct in order to obtain our identity public key.
With this change, if the user recovers their wallet with the same seed,
then they’ll have access to the same prior node identity. This change
also makes it easy for us to support node key rotation in the future by
bumping up our requested index.

lnd.go

@@ -37,6 +37,7 @@ import (
 	flags "github.com/jessevdk/go-flags"
 	"github.com/lightningnetwork/lnd/autopilot"
 	"github.com/lightningnetwork/lnd/channeldb"
+	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lnrpc"
 	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/lnwallet/btcwallet"
@@ -237,7 +238,13 @@ func lndMain() error {
 	primaryChain := registeredChains.PrimaryChain()
 	registeredChains.RegisterChain(primaryChain, activeChainControl)
 
-	idPrivKey, err := activeChainControl.wallet.GetIdentitykey()
+	// TODO(roasbeef): add rotation
+	idPrivKey, err := activeChainControl.wallet.DerivePrivKey(keychain.KeyDescriptor{
+		KeyLocator: keychain.KeyLocator{
+			Family: keychain.KeyFamilyNodeKey,
+			Index:  0,
+		},
+	})
 	if err != nil {
 		return err
 	}
@@ -252,8 +259,9 @@ func lndMain() error {
 
 	// Set up the core server which will listen for incoming peer
 	// connections.
-	server, err := newServer(cfg.Listeners, chanDB, activeChainControl,
+	server, err := newServer(
-		idPrivKey)
+		cfg.Listeners, chanDB, activeChainControl, idPrivKey,
+	)
 	if err != nil {
 		srvrLog.Errorf("unable to create server: %v\n", err)
 		return err

mock.go

@@ -203,8 +203,7 @@ func (*mockWalletController) FetchInputInfo(
 	}
 	return txOut, nil
 }
-func (*mockWalletController) ConfirmedBalance(confs int32,
+func (*mockWalletController) ConfirmedBalance(confs int32) (btcutil.Amount, error) {
-	witness bool) (btcutil.Amount, error) {
 	return 0, nil
 }
 

pilot.go

@@ -146,7 +146,7 @@ func initAutoPilot(svr *server, cfg *autoPilotConfig) (*autopilot.Agent, error)
 		Heuristic:      prefAttachment,
 		ChanController: &chanController{svr},
 		WalletBalance: func() (btcutil.Amount, error) {
-			return svr.cc.wallet.ConfirmedBalance(1, true)
+			return svr.cc.wallet.ConfirmedBalance(1)
 		},
 		Graph: autopilot.ChannelGraphFromDatabase(svr.chanDB.ChannelGraph()),
 	}