feat: Support StorageClass relationships

Signed-off-by: Justin Toh <tohjustin@hotmail.com>

README.md

@@ -96,6 +96,7 @@ List of supported relationships used for discovering dependent objects:
   - [Pod References](https://kubernetes.io/docs/reference/kubernetes-api/workload-resources/pod-v1/)
   - [Service References](https://kubernetes.io/docs/reference/kubernetes-api/service-resources/service-v1/)
   - [ServiceAccount References](https://kubernetes.io/docs/reference/kubernetes-api/authentication-resources/service-account-v1/)
+  - [StorageClass References](https://kubernetes.io/docs/reference/kubernetes-api/config-and-storage-resources/storage-class-v1/)
 - Helm
   - [Release References](https://helm.sh/docs/intro/using_helm/#three-big-concepts) & [Storage References](https://helm.sh/docs/topics/advanced/#storage-backends)
 

internal/graph/graph.go

@@ -450,6 +450,13 @@ func ResolveDependents(m meta.RESTMapper, objects []unstructuredv1.Unstructured,
 				klog.V(4).Infof("Failed to get relationships for csinode named \"%s\": %s: %s", node.Name, err)
 				continue
 			}
+		// Populate dependents based on StorageClass relationships
+		case node.Group == "storage.k8s.io" && node.Kind == "StorageClass":
+			rmap, err = getStorageClassRelationships(node)
+			if err != nil {
+				klog.V(4).Infof("Failed to get relationships for storageclass named \"%s\": %s: %s", node.Name, err)
+				continue
+			}
 		default:
 			continue
 		}

internal/graph/kubernetes.go

@@ -1,6 +1,8 @@
 package graph
 
 import (
+	"strings"
+
 	admissionregistrationv1 "k8s.io/api/admissionregistration/v1"
 	corev1 "k8s.io/api/core/v1"
 	extensionsv1beta1 "k8s.io/api/extensions/v1beta1"
@@ -60,6 +62,9 @@ const (
 	// Kubernetes ServiceAccount relationships.
 	RelationshipServiceAccountSecret          Relationship = "ServiceAccountSecret"
 	RelationshipServiceAccountImagePullSecret Relationship = "ServiceAccountImagePullSecret"
+
+	// Kubernetes StorageClass relationships.
+	RelationshipStorageClassProvisioner Relationship = "StorageClassProvisioner"
 )
 
 // getClusterRoleRelationships returns a map of relationships that this
@@ -549,6 +554,28 @@ func getServiceAccountRelationships(n *Node) (*RelationshipMap, error) {
 	return &result, nil
 }
 
+// getStorageClassRelationships returns a map of relationships that this
+// StorageClass has with other objects, based on what was referenced in its
+// manifest.
+func getStorageClassRelationships(n *Node) (*RelationshipMap, error) {
+	var sc storagev1.StorageClass
+	err := runtime.DefaultUnstructuredConverter.FromUnstructured(n.UnstructuredContent(), &sc)
+	if err != nil {
+		return nil, err
+	}
+
+	var ref ObjectReference
+	result := newRelationshipMap()
+
+	// RelationshipStorageClassProvisioner (external provisioners only)
+	if p := sc.Provisioner; len(p) > 0 && !strings.HasPrefix(p, "kubernetes.io/") {
+		ref = ObjectReference{Group: "storage.k8s.io", Kind: "CSIDriver", Name: p}
+		result.AddDependencyByKey(ref.Key(), RelationshipStorageClassProvisioner)
+	}
+
+	return &result, nil
+}
+
 // getValidatingWebhookConfigurationRelationships returns a map of relationships
 // that this ValidatingWebhookConfiguration has with other objects, based on
 // what was referenced in its manifest.