util/cachepersister: check and return CacheEntryNotFound error in Get()

pkg/util/cachepersister.go

@@ -23,13 +23,19 @@ import (
 )
 
 const (
-	//PluginFolder defines location of plugins
+	// PluginFolder defines location of plugins
 	PluginFolder = "/var/lib/kubelet/plugins"
 )
 
-// ForAllFunc stores metadata with identifier
+// ForAllFunc is a unary predicate for visiting all cache entries
+// matching the `pattern' in CachePersister's ForAll function.
 type ForAllFunc func(identifier string) error
 
+// CacheEntryNotFound is an error type for "Not Found" cache errors
+type CacheEntryNotFound struct {
+	error
+}
+
 // CachePersister interface implemented for store
 type CachePersister interface {
 	Create(identifier string, data interface{}) error

pkg/util/k8scmcache.go

@@ -159,6 +159,10 @@ func (k8scm *K8sCMCache) Create(identifier string, data interface{}) error {
 func (k8scm *K8sCMCache) Get(identifier string, data interface{}) error {
 	cm, err := k8scm.getMetadataCM(identifier)
 	if err != nil {
+		if apierrs.IsNotFound(err) {
+			return &CacheEntryNotFound{err}
+		}
+
 		return err
 	}
 	err = json.Unmarshal([]byte(cm.Data[cmDataKey]), data)

pkg/util/nodecache.go

@@ -130,6 +130,10 @@ func (nc *NodeCache) Get(identifier string, data interface{}) error {
 	// #nosec
 	fp, err := os.Open(file)
 	if err != nil {
+		if os.IsNotExist(errors.Cause(err)) {
+			return &CacheEntryNotFound{err}
+		}
+
 		return errors.Wrapf(err, "node-cache: open error for %s", file)
 	}