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

client/pkg/fileutil/fileutil.go

@@ -135,3 +135,35 @@ func CheckDirPermission(dir string, perm os.FileMode) error {
 	}
 	return nil
 }
+
+// RemoveMatchFile deletes file if matchFunc is true on an existing dir
+// Returns error if the dir does not exist or remove file fail
+func RemoveMatchFile(lg *zap.Logger, dir string, matchFunc func(fileName string) bool) error {
+	if lg == nil {
+		lg = zap.NewNop()
+	}
+	if !Exist(dir) {
+		return fmt.Errorf("directory %s does not exist", dir)
+	}
+	fileNames, err := ReadDir(dir)
+	if err != nil {
+		return err
+	}
+	var removeFailedFiles []string
+	for _, fileName := range fileNames {
+		if matchFunc(fileName) {
+			file := filepath.Join(dir, fileName)
+			if err = os.Remove(file); err != nil {
+				removeFailedFiles = append(removeFailedFiles, fileName)
+				lg.Error("remove file failed",
+					zap.String("file", file),
+					zap.Error(err))
+				continue
+			}
+		}
+	}
+	if len(removeFailedFiles) != 0 {
+		return fmt.Errorf("remove file(s) %v error", removeFailedFiles)
+	}
+	return nil
+}

client/pkg/fileutil/fileutil_test.go

@@ -26,6 +26,8 @@ import (
 	"strings"
 	"testing"
 	"time"
+
+	"go.uber.org/zap/zaptest"
 )
 
 func TestIsDirWriteable(t *testing.T) {
@@ -192,3 +194,44 @@ func TestDirPermission(t *testing.T) {
 		t.Errorf("expected error, got nil")
 	}
 }
+
+func TestRemoveMatchFile(t *testing.T) {
+	tmpdir := t.TempDir()
+	defer os.RemoveAll(tmpdir)
+	f, err := ioutil.TempFile(tmpdir, "tmp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+	f, err = ioutil.TempFile(tmpdir, "foo.tmp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+
+	err = RemoveMatchFile(zaptest.NewLogger(t), tmpdir, func(fileName string) bool {
+		return strings.HasPrefix(fileName, "tmp")
+	})
+	if err != nil {
+		t.Errorf("expected nil, got error")
+	}
+	fnames, err := ReadDir(tmpdir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(fnames) != 1 {
+		t.Errorf("expected exist 1 files, got %d", len(fnames))
+	}
+
+	f, err = ioutil.TempFile(tmpdir, "tmp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = RemoveMatchFile(zaptest.NewLogger(t), tmpdir, func(fileName string) bool {
+		return strings.HasPrefix(fileName, "tmp")
+	})
+	if err == nil {
+		t.Errorf("expected error, got nil")
+	}
+	f.Close()
+}

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()