Using apimachinery to manipulate the lists

pkg/cache/cache_test.go

@@ -182,6 +182,7 @@ func CacheTest(createCacheFunc func(config *rest.Config, opts cache.Options) (ca
 				It("should support filtering by labels from multiple namespaces", func() {
 					By("creating another pod with the same label but different namespace")
 					anotherPod := createPod("test-pod-2", testNamespaceOne, kcorev1.RestartPolicyAlways)
+					defer deletePod(anotherPod)
 
 					By("listing pods with a particular label")
 					// NB: each pod has a "test-label": <pod-name>
@@ -195,8 +196,6 @@ func CacheTest(createCacheFunc func(config *rest.Config, opts cache.Options) (ca
 					for _, actual := range out.Items {
 						Expect(actual.Labels["test-label"]).To(Equal("test-pod-2"))
 					}
-
-					deletePod(anotherPod)
 				})
 
 				It("should be able to list objects by namespace", func() {
@@ -313,6 +312,7 @@ func CacheTest(createCacheFunc func(config *rest.Config, opts cache.Options) (ca
 				It("should support filtering by labels from multiple namespaces", func() {
 					By("creating another pod with the same label but different namespace")
 					anotherPod := createPod("test-pod-2", testNamespaceOne, kcorev1.RestartPolicyAlways)
+					defer deletePod(anotherPod)
 
 					By("listing pods with a particular label")
 					// NB: each pod has a "test-label": <pod-name>
@@ -333,7 +333,6 @@ func CacheTest(createCacheFunc func(config *rest.Config, opts cache.Options) (ca
 						Expect(actual.GetLabels()["test-label"]).To(Equal("test-pod-2"))
 					}
 
-					deletePod(anotherPod)
 				})
 
 				It("should be able to list objects by namespace", func() {

pkg/cache/multi_namespace_cache.go

@@ -18,11 +18,12 @@ package cache
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"time"
 
 	corev1 "k8s.io/api/core/v1"
+	apimeta "k8s.io/apimachinery/pkg/api/meta"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
@@ -133,6 +134,24 @@ func (c *multiNamespaceCache) Get(ctx context.Context, key client.ObjectKey, obj
 	return cache.Get(ctx, key, obj)
 }
 
+func (c *multiNamespaceCache) getNewObj(list runtime.Object) (runtime.Object, error) {
+	// Get all the objects in the namespaces we are watching.
+	gvk, err := apiutil.GVKForObject(list, c.Scheme)
+	if err != nil {
+		return nil, err
+	}
+	if _, ok := list.(*unstructured.UnstructuredList); ok {
+		obj := &unstructured.UnstructuredList{}
+		obj.SetGroupVersionKind(gvk)
+		return obj, nil
+	}
+	listObj, err := c.Scheme.New(gvk)
+	if err != nil {
+		return nil, err
+	}
+	return listObj, nil
+}
+
 // List multi namespace cache will get all the objects in the namespaces that the cache is watching if asked for all namespaces.
 func (c *multiNamespaceCache) List(ctx context.Context, list runtime.Object, opts ...client.ListOptionFunc) error {
 	listOpts := client.ListOptions{}
@@ -145,28 +164,40 @@ func (c *multiNamespaceCache) List(ctx context.Context, list runtime.Object, opt
 		return cache.List(ctx, list, opts...)
 	}
 
-	// Get all the objects in the namespaces we are watching.
-	gvk, err := apiutil.GVKForObject(list, c.Scheme)
+	listAccessor, ok := list.(metav1.ListInterface)
+	if !ok {
+		return fmt.Errorf("object: %T must be a list type", list)
+	}
+
+	allItems, err := apimeta.ExtractList(list)
 	if err != nil {
 		return err
 	}
-	allItems := &unstructured.UnstructuredList{}
+	var resourceVersion string
 	for _, cache := range c.namespaceToCache {
-		items := &unstructured.UnstructuredList{}
-		items.SetGroupVersionKind(gvk)
-		err := cache.List(ctx, items, opts...)
+		listObj, err := c.getNewObj(list)
+		if err != nil {
+			return err
+		}
+		err = cache.List(ctx, listObj, opts...)
+		if err != nil {
+			return err
+		}
+		items, err := apimeta.ExtractList(listObj)
 		if err != nil {
 			return err
 		}
-		allItems.Items = append(allItems.Items, items.Items...)
+		accessor, ok := listObj.(metav1.ListInterface)
+		if !ok {
+			return fmt.Errorf("object: %T must be a list type", list)
+		}
+		allItems = append(allItems, items...)
 		// The last list call should have the most correct resource version.
-		allItems.Object = items.Object
-	}
-	data, err := allItems.MarshalJSON()
-	if err != nil {
-		return err
+		resourceVersion = accessor.GetResourceVersion()
 	}
-	return json.Unmarshal(data, list)
+	listAccessor.SetResourceVersion(resourceVersion)
+
+	return apimeta.SetList(list, allItems)
 }
 
 // multiNamespaceInformer knows how to handle interacting with the underlying informer across multiple namespaces