print lightning log to local file

cmd/tidb-lightning/main.go

@@ -28,6 +28,8 @@ import (
 
 func main() {
 	cfg := config.Must(config.LoadGlobalConfig(os.Args[1:], nil))
+	fmt.Fprintf(os.Stdout, "Verbose debug logs will be written to %s.\n\n", cfg.App.Config.File)
+
 	app := lightning.New(cfg)
 
 	sc := make(chan os.Signal, 1)
@@ -63,6 +65,7 @@ func main() {
 	err := app.GoServe()
 	if err != nil {
 		logger.Error("failed to start HTTP server", zap.Error(err))
+		fmt.Fprintln(os.Stderr, "failed to start HTTP server:", err)
 		return
 	}
 
@@ -72,9 +75,12 @@ func main() {
 		err = app.RunOnce()
 	}
 	if err != nil {
-		logger.Error("tidb lightning encountered error", zap.Error(err))
+		logger.Error("tidb lightning encountered error stack info", zap.Error(err))
+		logger.Error("tidb lightning encountered error", log.ShortError(err))
+		fmt.Fprintln(os.Stderr, "tidb lightning encountered error: ", err)
 	} else {
 		logger.Info("tidb lightning exit")
+		fmt.Fprintln(os.Stdout, "tidb lightning exit")
 	}
 
 	syncErr := logger.Sync()

lightning/config/global.go

@@ -18,6 +18,8 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"path/filepath"
+	"time"
 
 	"github.com/BurntSushi/toml"
 	"github.com/pingcap/errors"
@@ -116,6 +118,10 @@ func Must(cfg *GlobalConfig, err error) *GlobalConfig {
 	return cfg
 }
 
+func timestampLogFileName() string {
+	return filepath.Join(os.TempDir(), time.Now().Format("lightning.log.2006-01-02T15.04.05Z0700"))
+}
+
 // LoadGlobalConfig reads the arguments and fills in the GlobalConfig.
 func LoadGlobalConfig(args []string, extraFlags func(*flag.FlagSet)) (*GlobalConfig, error) {
 	cfg := NewGlobalConfig()
@@ -130,7 +136,7 @@ func LoadGlobalConfig(args []string, extraFlags func(*flag.FlagSet)) (*GlobalCon
 	printVersion := fs.Bool("V", false, "print version of lightning")
 
 	logLevel := fs.String("L", "", `log level: info, debug, warn, error, fatal (default "info")`)
-	logFilePath := fs.String("log-file", "", "log file path")
+	logFilePath := fs.String("log-file", timestampLogFileName(), "log file path")
 	tidbHost := fs.String("tidb-host", "", "TiDB server host")
 	tidbPort := fs.Int("tidb-port", 0, "TiDB server port (default 4000)")
 	tidbUser := fs.String("tidb-user", "", "TiDB user name to connect")

lightning/restore/restore.go

@@ -599,6 +599,7 @@ func (rc *RestoreController) restoreTables(ctx context.Context) error {
 				tableLogTask := task.tr.logger.Begin(zap.InfoLevel, "restore table")
 				web.BroadcastTableCheckpoint(task.tr.tableName, task.cp)
 				err := task.tr.restoreTable(ctx2, rc, task.cp)
+				err = errors.Annotatef(err, "restore table %s failed", task.tr.tableName)
 				tableLogTask.End(zap.ErrorLevel, err)
 				web.BroadcastError(task.tr.tableName, err)
 				metric.RecordTableCount("completed", err)
@@ -1246,7 +1247,7 @@ func (rc *RestoreController) cleanCheckpoints(ctx context.Context) error {
 		err = rc.checkpointsDB.RemoveCheckpoint(ctx, "all")
 	}
 	task.End(zap.ErrorLevel, err)
-	return errors.Trace(err)
+	return errors.Annotate(err, "clean checkpoints")
 }
 
 type chunkRestore struct {