Fix non-cache client list

This fixes the non-cache client list, which had a null pointer
dereference (opts.Namespace), incorrect resource handling (need the
resource for the items, not the list itself), and incorrect handling of
nil list options (the underlying metav1.ListOptions needs to always be
non-nil, even if empty).

Author: DirectXMan12

pkg/client/client.go

@@ -142,8 +142,12 @@ func (c *client) List(ctx context.Context, opts *ListOptions, obj runtime.Object
 	if err != nil {
 		return err
 	}
+	namespace := ""
+	if opts != nil {
+		namespace = opts.Namespace
+	}
 	return r.Get().
-		NamespaceIfScoped(opts.Namespace, r.isNamespaced()).
+		NamespaceIfScoped(namespace, r.isNamespaced()).
 		Resource(r.resource()).
 		Body(obj).
 		VersionedParams(opts.AsListOptions(), c.paramCodec).

pkg/client/client_cache.go

@@ -18,6 +18,7 @@ package client
 
 import (
 	"reflect"
+	"strings"
 	"sync"
 
 	"k8s.io/apimachinery/pkg/api/meta"
@@ -49,11 +50,18 @@ type clientCache struct {
 }
 
 // newResource maps obj to a Kubernetes Resource and constructs a client for that Resource.
+// If the object is a list, the resource represents the item's type instead.
 func (c *clientCache) newResource(obj runtime.Object) (*resourceMeta, error) {
 	gvk, err := apiutil.GVKForObject(obj, c.scheme)
 	if err != nil {
 		return nil, err
 	}
+
+	if strings.HasSuffix(gvk.Kind, "List") && meta.IsListType(obj) {
+		// if this was a list, treat it as a request for the item's resource
+		gvk.Kind = gvk.Kind[:len(gvk.Kind)-4]
+	}
+
 	client, err := apiutil.RESTClientForGVK(gvk, c.config, c.codecs)
 	if err != nil {
 		return nil, err
@@ -65,7 +73,8 @@ func (c *clientCache) newResource(obj runtime.Object) (*resourceMeta, error) {
 	return &resourceMeta{Interface: client, mapping: mapping, gvk: gvk}, nil
 }
 
-// getResource returns a raw rest.Client for the given object type.
+// getResource returns the resource meta information for the given type of object.
+// If the object is a list, the resource represents the item's type instead.
 func (c *clientCache) getResource(obj runtime.Object) (*resourceMeta, error) {
 	typ := reflect.TypeOf(obj)
 

pkg/client/client_test.go

@@ -18,9 +18,7 @@ package client_test
 
 import (
 	"context"
-
 	"fmt"
-
 	"sync/atomic"
 
 	. "github.com/onsi/ginkgo"
@@ -353,7 +351,26 @@ var _ = Describe("Client", func() {
 
 	Describe("List", func() {
 		It("should fetch collection of objects", func() {
+			By("creating an initial object")
+			dep, err := clientset.AppsV1().Deployments(ns).Create(dep)
+			Expect(err).NotTo(HaveOccurred())
+
+			cl, err := client.New(cfg, client.Options{})
+			Expect(err).NotTo(HaveOccurred())
 
+			By("listing all objects of that type in the cluster")
+			deps := &appsv1.DeploymentList{}
+			Expect(cl.List(context.Background(), nil, deps)).NotTo(HaveOccurred())
+
+			Expect(deps.Items).NotTo(BeEmpty())
+			hasDep := false
+			for _, item := range deps.Items {
+				if item.Name == dep.Name && item.Namespace == dep.Namespace {
+					hasDep = true
+					break
+				}
+			}
+			Expect(hasDep).To(BeTrue())
 		})
 
 		It("should return an empty list if there are no matching objects", func() {

pkg/client/interfaces.go

@@ -127,10 +127,14 @@ func (o *ListOptions) SetFieldSelector(selRaw string) error {
 // This may mutate the Raw field.
 func (o *ListOptions) AsListOptions() *metav1.ListOptions {
 	if o == nil {
-		return nil
+		return &metav1.ListOptions{}
+	}
+	if o.LabelSelector != nil {
+		o.Raw.LabelSelector = o.LabelSelector.String()
+	}
+	if o.FieldSelector != nil {
+		o.Raw.FieldSelector = o.FieldSelector.String()
 	}
-	o.Raw.LabelSelector = o.LabelSelector.String()
-	o.Raw.FieldSelector = o.FieldSelector.String()
 	return o.Raw
 }