db: skip SQL migration when no kvdb files exist

Avoid creating legacy bbolt database files when the kvdb-to-SQL
programmatic migration runs on a node that never had LiT kvdb state.

Note that we only skip the creating the database file if there is no
single bbolt database file. If for example there's only 1 existing
bbolt database file, we will still create the new bbolt database file
for the other 2 bbolt databases, as we for example need to pass the
accounts & session databases to the firewalldb migration, and we'd want
to avoid having the migrations become more complex by having to handle
the case where the other databases are missing.

db/migsets/programmatic_migrations.go

@@ -6,12 +6,14 @@ import (
 	"encoding/binary"
 	"errors"
 	"fmt"
+	"path/filepath"
 	"time"
 
 	"github.com/golang-migrate/migrate/v4"
 	"github.com/golang-migrate/migrate/v4/database"
 	"github.com/lightninglabs/lightning-terminal/accounts"
 	"github.com/lightninglabs/lightning-terminal/db/sqlcmig6"
+	"github.com/lightninglabs/lightning-terminal/db/tombstone"
 	"github.com/lightninglabs/lightning-terminal/firewalldb"
 	"github.com/lightninglabs/lightning-terminal/session"
 	"github.com/lightningnetwork/lnd/clock"
@@ -88,6 +90,40 @@ func kvdbToSqlProgrammaticMigration(ctx context.Context,
 	_ *sqldb.BaseDB, clock clock.Clock, q *sqlcmig6.Queries) error {
 
 	start := time.Now()
+
+	accountsActive, err := tombstone.KVDBFileExists(
+		filepath.Join(accountsDir, accounts.DBFilename),
+	)
+	if err != nil {
+		return fmt.Errorf("unable to inspect accounts kvdb: %w", err)
+	}
+
+	sessionsActive, err := tombstone.KVDBFileExists(
+		filepath.Join(networkDir, session.DBFilename),
+	)
+	if err != nil {
+		return fmt.Errorf("unable to inspect session kvdb: %w", err)
+	}
+
+	firewallActive, err := tombstone.KVDBFileExists(
+		filepath.Join(networkDir, firewalldb.DBFilename),
+	)
+	if err != nil {
+		return fmt.Errorf("unable to inspect rules kvdb: %w", err)
+	}
+
+	if !accountsActive && !sessionsActive && !firewallActive {
+		log.Infof("Skipping KVDB to SQL migration for all stores: " +
+			"no legacy database files exist")
+
+		return nil
+	}
+
+	if basicClient == nil {
+		return errors.New("lightning client is required for " +
+			"migration but was nil")
+	}
+
 	log.Infof("Starting KVDB to SQL migration for all stores")
 
 	accountStore, err := accounts.NewBoltStoreForMigration(

db/migsets/programmatic_migrations_test.go

@@ -0,0 +1,152 @@
+package migsets
+
+import (
+	"context"
+	"net"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/lightninglabs/lightning-terminal/accounts"
+	"github.com/lightninglabs/lightning-terminal/db"
+	"github.com/lightninglabs/lightning-terminal/db/sqlcmig6"
+	"github.com/lightninglabs/lightning-terminal/firewalldb"
+	"github.com/lightninglabs/lightning-terminal/session"
+	"github.com/lightningnetwork/lnd/clock"
+	"github.com/lightningnetwork/lnd/lnrpc"
+	"github.com/lightningnetwork/lnd/sqldb/v2"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+	"google.golang.org/grpc/test/bufconn"
+)
+
+// TestKVDBToSQLProgrammaticMigrationSkipsMissingStores verifies that the kvdb
+// to SQL migration does not create missing legacy kvdb files while scanning for
+// stores to migrate.
+func TestKVDBToSQLProgrammaticMigrationSkipsMissingStores(t *testing.T) {
+	t.Parallel()
+
+	accountsDir := t.TempDir()
+	networkDir := t.TempDir()
+
+	sqlStore := sqldb.NewTestSqliteDB(t, db.MakeTestMigrationSets())
+	queries := sqlcmig6.NewForType(
+		sqlStore.BaseDB, sqlStore.BackendType,
+	)
+
+	err := kvdbToSqlProgrammaticMigration(
+		context.Background(), nil, accountsDir, networkDir,
+		sqlStore.BaseDB, clock.NewDefaultClock(), queries,
+	)
+	require.NoError(t, err)
+
+	requireNoFile(t, filepath.Join(accountsDir, accounts.DBFilename))
+	requireNoFile(t, filepath.Join(networkDir, session.DBFilename))
+	requireNoFile(t, filepath.Join(networkDir, firewalldb.DBFilename))
+}
+
+// TestKVDBToSQLProgrammaticMigrationRunsWithOneBBoltDBFiles verifies that the
+// migration still runs when only the accounts kvdb exists, creates the missing
+// legacy files, and migrates the existing account data to SQL.
+func TestKVDBToSQLProgrammaticMigrationRunsWithOneBBoltDBFiles(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+	testClock := clock.NewDefaultClock()
+	accountsDir := t.TempDir()
+	networkDir := t.TempDir()
+
+	accountStore, err := accounts.NewBoltStore(
+		accountsDir, accounts.DBFilename, testClock,
+	)
+	require.NoError(t, err)
+
+	_, err = accountStore.NewAccount(ctx, 1234, time.Time{}, "acct-1")
+	require.NoError(t, err)
+	require.NoError(t, accountStore.Close())
+
+	sqlStore := sqldb.NewTestSqliteDB(t, db.MakeTestMigrationSets())
+	queries := sqlcmig6.NewForType(
+		sqlStore.BaseDB, sqlStore.BackendType,
+	)
+
+	lndClient := newTestLightningClient(t)
+
+	err = kvdbToSqlProgrammaticMigration(
+		ctx, lndClient, accountsDir, networkDir,
+		sqlStore.BaseDB, testClock, queries,
+	)
+	require.NoError(t, err)
+
+	requireFileExists(t, filepath.Join(accountsDir, accounts.DBFilename))
+	requireFileExists(t, filepath.Join(networkDir, session.DBFilename))
+	requireFileExists(t, filepath.Join(networkDir, firewalldb.DBFilename))
+
+	dbAccounts, err := queries.ListAllAccounts(ctx)
+	require.NoError(t, err)
+	require.Len(t, dbAccounts, 1)
+
+	dbSessions, err := queries.ListSessions(ctx)
+	require.NoError(t, err)
+	require.Empty(t, dbSessions)
+}
+
+func requireNoFile(t *testing.T, path string) {
+	t.Helper()
+
+	_, err := os.Stat(path)
+	require.ErrorIs(t, err, os.ErrNotExist)
+}
+
+func requireFileExists(t *testing.T, path string) {
+	t.Helper()
+
+	_, err := os.Stat(path)
+	require.NoError(t, err)
+}
+
+func newTestLightningClient(t *testing.T) lnrpc.LightningClient {
+	t.Helper()
+
+	lis := bufconn.Listen(1024 * 1024)
+	server := grpc.NewServer()
+	lnrpc.RegisterLightningServer(server, &testLightningServer{})
+
+	go func() {
+		_ = server.Serve(lis)
+	}()
+
+	t.Cleanup(func() {
+		server.Stop()
+		require.NoError(t, lis.Close())
+	})
+
+	conn, err := grpc.DialContext(
+		context.Background(), "passthrough:///bufnet",
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+		grpc.WithContextDialer(
+			func(context.Context, string) (net.Conn, error) {
+				return lis.Dial()
+			},
+		),
+	)
+	require.NoError(t, err)
+
+	t.Cleanup(func() {
+		require.NoError(t, conn.Close())
+	})
+
+	return lnrpc.NewLightningClient(conn)
+}
+
+type testLightningServer struct {
+	lnrpc.UnimplementedLightningServer
+}
+
+func (t *testLightningServer) ListMacaroonIDs(context.Context,
+	*lnrpc.ListMacaroonIDsRequest) (*lnrpc.ListMacaroonIDsResponse, error) {
+
+	return &lnrpc.ListMacaroonIDsResponse{}, nil
+}