etcdserver: remove temp files in snap dir when etcdServer starting

When etcd exits abnormally, tmp files will remain in snap dir, so clean up tmp files in snap dir when etcdserver starting.

Fixes #12837

server/etcdserver/server.go

@@ -26,6 +26,7 @@ import (
 	"path"
 	"regexp"
 	"strconv"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -338,6 +339,17 @@ func NewServer(cfg config.ServerConfig) (srv *EtcdServer, err error) {
 			zap.Error(err),
 		)
 	}
+
+	if err = fileutil.RemoveMatchFile(cfg.Logger, cfg.SnapDir(), func(fileName string) bool {
+		return strings.HasPrefix(fileName, "tmp")
+	}); err != nil {
+		cfg.Logger.Error(
+			"failed to remove temp file(s) in snapshot directory",
+			zap.String("path", cfg.SnapDir()),
+			zap.Error(err),
+		)
+	}
+
 	ss := snap.New(cfg.Logger, cfg.SnapDir())
 
 	bepath := cfg.BackendPath()