initialize directory while creating checkpoint file store

pkg/kubelet/dockershim/checkpoint_store.go

@@ -57,15 +57,19 @@ type FileStore struct {
 	path string
 }
 
+func NewFileStore(path string) (CheckpointStore, error) {
+	if err := ensurePath(path); err != nil {
+		return nil, err
+	}
+	return &FileStore{path: path}, nil
+}
+
 func (fstore *FileStore) Write(key string, data []byte) error {
 	if err := validateKey(key); err != nil {
 		return err
 	}
-	if _, err := os.Stat(fstore.path); err != nil {
-		// if directory already exists, proceed
-		if err = os.MkdirAll(fstore.path, 0755); err != nil && !os.IsExist(err) {
-			return err
-		}
+	if err := ensurePath(fstore.path); err != nil {
+		return err
 	}
 	tmpfile := filepath.Join(fstore.path, fmt.Sprintf("%s%s%s", tmpPrefix, key, tmpSuffix))
 	if err := ioutil.WriteFile(tmpfile, data, 0644); err != nil {
@@ -113,6 +117,15 @@ func (fstore *FileStore) getCheckpointPath(key string) string {
 	return filepath.Join(fstore.path, key)
 }
 
+// ensurePath creates input directory if it does not exist
+func ensurePath(path string) error {
+	if _, err := os.Stat(path); err != nil {
+		// MkdirAll returns nil if directory already exists
+		return os.MkdirAll(path, 0755)
+	}
+	return nil
+}
+
 func validateKey(key string) error {
 	if len(key) <= keyMaxLength && keyRegex.MatchString(key) {
 		return nil

pkg/kubelet/dockershim/checkpoint_store_test.go

@@ -30,7 +30,8 @@ func TestFileStore(t *testing.T) {
 	path, err := ioutil.TempDir("", "FileStore")
 	assert.NoError(t, err)
 	defer cleanUpTestPath(t, path)
-	store := &FileStore{path: path}
+	store, err := NewFileStore(path)
+	assert.NoError(t, err)
 
 	Checkpoints := []struct {
 		key       string

pkg/kubelet/dockershim/docker_checkpoint.go

@@ -84,8 +84,12 @@ type PersistentCheckpointHandler struct {
 	store CheckpointStore
 }
 
-func NewPersistentCheckpointHandler() CheckpointHandler {
-	return &PersistentCheckpointHandler{store: &FileStore{path: filepath.Join(dockershimRootDir, sandboxCheckpointDir)}}
+func NewPersistentCheckpointHandler() (CheckpointHandler, error) {
+	fstore, err := NewFileStore(filepath.Join(dockershimRootDir, sandboxCheckpointDir))
+	if err != nil {
+		return nil, err
+	}
+	return &PersistentCheckpointHandler{store: fstore}, nil
 }
 
 func (handler *PersistentCheckpointHandler) CreateCheckpoint(podSandboxID string, checkpoint *PodSandboxCheckpoint) error {

pkg/kubelet/dockershim/docker_service.go

@@ -147,6 +147,10 @@ var internalLabelKeys []string = []string{containerTypeLabelKey, containerLogPat
 func NewDockerService(client dockertools.DockerInterface, seccompProfileRoot string, podSandboxImage string, streamingConfig *streaming.Config,
 	pluginSettings *NetworkPluginSettings, cgroupsName string, kubeCgroupDriver string, execHandler dockertools.ExecHandler) (DockerService, error) {
 	c := dockertools.NewInstrumentedDockerInterface(client)
+	checkpointHandler, err := NewPersistentCheckpointHandler()
+	if err != nil {
+		return nil, err
+	}
 	ds := &dockerService{
 		seccompProfileRoot: seccompProfileRoot,
 		client:             c,
@@ -157,7 +161,7 @@ func NewDockerService(client dockertools.DockerInterface, seccompProfileRoot str
 			execHandler: execHandler,
 		},
 		containerManager:  cm.NewContainerManager(cgroupsName, client),
-		checkpointHandler: NewPersistentCheckpointHandler(),
+		checkpointHandler: checkpointHandler,
 	}
 	if streamingConfig != nil {
 		var err error