Merge pull request #4949 from koba1t/fix/add_check_kustomization_is_empty

add check that kustomization is empty

api/types/kustomization.go

@@ -7,6 +7,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"reflect"
 
 	"sigs.k8s.io/kustomize/kyaml/errors"
 	"sigs.k8s.io/kustomize/kyaml/filesys"
@@ -300,6 +301,20 @@ func (k *Kustomization) FixKustomizationPreMarshalling(fSys filesys.FileSystem)
 	return nil
 }
 
+func (k *Kustomization) CheckEmpty() error {
+	// generate empty Kustomization
+	emptyKustomization := &Kustomization{}
+
+	// k.TypeMeta is metadata. It Isn't related to whether empty or not.
+	emptyKustomization.TypeMeta = k.TypeMeta
+
+	if reflect.DeepEqual(k, emptyKustomization) {
+		return fmt.Errorf("kustomization.yaml is empty")
+	}
+
+	return nil
+}
+
 func (k *Kustomization) EnforceFields() []string {
 	var errs []string
 	if k.Kind != "" && k.Kind != KustomizationKind && k.Kind != ComponentKind {