fall back to direct client if split client GET returns 404

Cf. bluek8s#267

To ensure this, remove the direct export of the client from the shared pkg, and instead require calling shared.Get, shared.Create, etc.

For the most part those functions will call the split client, but Get will have the desired special behavior.

pkg/controller/kubedirectorcluster/cluster.go

@@ -85,7 +85,7 @@ func (r *ReconcileKubeDirectorCluster) syncCluster(
 			if (updateErr == nil) && finalizersChanged {
 				// See https://github.com/bluek8s/kubedirector/issues/194
 				// Migrate Client().Update() calls back to Patch() calls.
-				updateErr = shared.Client().Update(context.TODO(), cr)
+				updateErr = shared.Update(context.TODO(), cr)
 			}
 			// Bail out if we're done.
 			if updateErr == nil {

pkg/controller/kubedirectorcluster/kubedirectorcluster_controller.go

@@ -98,7 +98,7 @@ func (r *ReconcileKubeDirectorCluster) Reconcile(request reconcile.Request) (rec
 
 	// Fetch the KubeDirectorCluster instance.
 	cr := &kdv1.KubeDirectorCluster{}
-	err := shared.Client().Get(context.TODO(), request.NamespacedName, cr)
+	err := shared.Get(context.TODO(), request.NamespacedName, cr)
 	if err != nil {
 		// If the resource is not found, that means all of the finalizers have
 		// been removed, and the kubedirectorcluster resource has been deleted,

pkg/controller/kubedirectorconfig/config.go

@@ -77,7 +77,7 @@ func (r *ReconcileKubeDirectorConfig) syncConfig(
 			if statusChanged {
 				cr.Status.GenerationUID = uuid.New().String()
 				StatusGens.WriteStatusGen(cr.UID, cr.Status.GenerationUID)
-				updateErr = shared.Client().Status().Update(context.TODO(), cr)
+				updateErr = shared.StatusUpdate(context.TODO(), cr)
 				// If this succeeded, no need to do it again on next iteration
 				// if we're just cycling because of a failure to update the
 				// finalizer.
@@ -90,7 +90,7 @@ func (r *ReconcileKubeDirectorConfig) syncConfig(
 			if (updateErr == nil) && finalizersChanged {
 				// See https://github.com/bluek8s/kubedirector/issues/194
 				// Migrate Client().Update() calls back to Patch() calls.
-				updateErr = shared.Client().Update(context.TODO(), cr)
+				updateErr = shared.Update(context.TODO(), cr)
 			}
 			// Bail out if we're done.
 			if updateErr == nil {

pkg/controller/kubedirectorconfig/kubedirectorconfig_controller.go

@@ -100,7 +100,7 @@ func (r *ReconcileKubeDirectorConfig) Reconcile(request reconcile.Request) (reco
 
 	// Fetch the KubeDirectorConfig instance.
 	cr := &kdv1.KubeDirectorConfig{}
-	err := shared.Client().Get(context.TODO(), request.NamespacedName, cr)
+	err := shared.Get(context.TODO(), request.NamespacedName, cr)
 	if err != nil {
 		if errors.IsNotFound(err) {
 			// Request object not found, could have been deleted after

pkg/executor/cluster.go

@@ -32,7 +32,7 @@ func UpdateClusterStatus(
 	// emptystring, and remove any MemberStatus where Pod is emptystring.
 	compact(&(cr.Status.Roles))
 
-	return shared.Client().Status().Update(context.TODO(), cr)
+	return shared.StatusUpdate(context.TODO(), cr)
 }
 
 // compact edits the input slice of role statuses so that any elements that

pkg/executor/service.go

@@ -67,7 +67,7 @@ func CreateHeadlessService(
 	} else {
 		service.ObjectMeta.Name = cr.Status.ClusterService
 	}
-	err := shared.Client().Create(context.TODO(), service)
+	err := shared.Create(context.TODO(), service)
 
 	return service, err
 }
@@ -132,7 +132,7 @@ func CreatePodService(
 		}
 		service.Spec.Ports = append(service.Spec.Ports, servicePort)
 	}
-	createErr := shared.Client().Create(context.TODO(), service)
+	createErr := shared.Create(context.TODO(), service)
 	return service, createErr
 }
 
@@ -223,7 +223,7 @@ func DeletePodService(
 		},
 	}
 
-	return shared.Client().Delete(context.TODO(), toDelete)
+	return shared.Delete(context.TODO(), toDelete)
 }
 
 // UpdateService updates a service
@@ -233,7 +233,7 @@ func UpdateService(
 	service *corev1.Service,
 ) error {
 
-	err := shared.Client().Update(context.TODO(), service)
+	err := shared.Update(context.TODO(), service)
 	if err == nil {
 		return nil
 	}
@@ -254,7 +254,7 @@ func UpdateService(
 	// If there was a resourceVersion conflict then fetch a more
 	// recent version of the object and attempt to update that.
 	currentService := &corev1.Service{}
-	err = shared.Client().Get(
+	err = shared.Get(
 		context.TODO(),
 		types.NamespacedName{
 			Namespace: service.Namespace,
@@ -275,7 +275,7 @@ func UpdateService(
 	}
 
 	currentService.Spec.Type = service.Spec.Type
-	err = shared.Client().Update(context.TODO(), currentService)
+	err = shared.Update(context.TODO(), currentService)
 	if err != nil {
 		shared.LogErrorf(
 			reqLogger,

pkg/executor/statefulset.go

@@ -54,7 +54,7 @@ func CreateStatefulSet(
 	if err != nil {
 		return nil, err
 	}
-	return statefulSet, shared.Client().Create(context.TODO(), statefulSet)
+	return statefulSet, shared.Create(context.TODO(), statefulSet)
 }
 
 // UpdateStatefulSetReplicas modifies an existing statefulset in k8s to have
@@ -67,7 +67,7 @@ func UpdateStatefulSetReplicas(
 ) error {
 
 	*statefulSet.Spec.Replicas = replicas
-	err := shared.Client().Update(context.TODO(), statefulSet)
+	err := shared.Update(context.TODO(), statefulSet)
 	if err == nil {
 		return nil
 	}
@@ -93,7 +93,7 @@ func UpdateStatefulSetReplicas(
 		Name:      statefulSet.Name,
 	}
 	*statefulSet = appsv1.StatefulSet{}
-	err = shared.Client().Get(context.TODO(), name, statefulSet)
+	err = shared.Get(context.TODO(), name, statefulSet)
 	if err != nil {
 		shared.LogError(
 			reqLogger,
@@ -106,7 +106,7 @@ func UpdateStatefulSetReplicas(
 	}
 
 	*statefulSet.Spec.Replicas = replicas
-	err = shared.Client().Update(context.TODO(), statefulSet)
+	err = shared.Update(context.TODO(), statefulSet)
 	if err != nil {
 		shared.LogError(
 			reqLogger,
@@ -157,7 +157,7 @@ func DeleteStatefulSet(
 			Namespace: namespace,
 		},
 	}
-	return shared.Client().Delete(context.TODO(), toDelete)
+	return shared.Delete(context.TODO(), toDelete)
 }
 
 // getStatefulset composes the spec for creating a statefulset in k8s, based

pkg/executor/volume.go

@@ -39,5 +39,5 @@ func DeletePVC(
 			Namespace: namespace,
 		},
 	}
-	return shared.Client().Delete(context.TODO(), toDelete)
+	return shared.Delete(context.TODO(), toDelete)
 }

pkg/observer/observer.go

@@ -38,7 +38,7 @@ func GetCluster(
 ) (*kdv1.KubeDirectorCluster, error) {
 
 	result := &kdv1.KubeDirectorCluster{}
-	err := shared.Client().Get(
+	err := shared.Get(
 		context.TODO(),
 		types.NamespacedName{Namespace: namespace, Name: clusterName},
 		result,
@@ -54,7 +54,7 @@ func GetStatefulSet(
 ) (*appsv1.StatefulSet, error) {
 
 	result := &appsv1.StatefulSet{}
-	err := shared.Client().Get(
+	err := shared.Get(
 		context.TODO(),
 		types.NamespacedName{Namespace: namespace, Name: statefulSetName},
 		result,
@@ -69,7 +69,7 @@ func GetService(
 ) (*corev1.Service, error) {
 
 	result := &corev1.Service{}
-	err := shared.Client().Get(
+	err := shared.Get(
 		context.TODO(),
 		types.NamespacedName{Namespace: namespace, Name: serviceName},
 		result,
@@ -84,7 +84,7 @@ func GetPod(
 ) (*corev1.Pod, error) {
 
 	result := &corev1.Pod{}
-	err := shared.Client().Get(
+	err := shared.Get(
 		context.TODO(),
 		types.NamespacedName{Namespace: namespace, Name: podName},
 		result,
@@ -100,7 +100,7 @@ func GetPVC(
 ) (*corev1.PersistentVolumeClaim, error) {
 
 	result := &corev1.PersistentVolumeClaim{}
-	err := shared.Client().Get(
+	err := shared.Get(
 		context.TODO(),
 		types.NamespacedName{Namespace: namespace, Name: pvcName},
 		result,
@@ -116,7 +116,7 @@ func GetApp(
 ) (*kdv1.KubeDirectorApp, error) {
 
 	result := &kdv1.KubeDirectorApp{}
-	err := shared.Client().Get(
+	err := shared.Get(
 		context.TODO(),
 		types.NamespacedName{Namespace: namespace, Name: appName},
 		result,
@@ -136,7 +136,7 @@ func GetValidatorWebhook(
 		return nil, err
 	}
 	result := &v1beta1.MutatingWebhookConfiguration{}
-	err = shared.Client().Get(
+	err = shared.Get(
 		context.TODO(),
 		types.NamespacedName{Namespace: kdNamespace, Name: validator},
 		result,
@@ -151,7 +151,7 @@ func GetSecret(
 ) (*corev1.Secret, error) {
 
 	result := &corev1.Secret{}
-	err := shared.Client().Get(
+	err := shared.Get(
 		context.TODO(),
 		types.NamespacedName{Namespace: namespace, Name: secretName},
 		result,
@@ -169,7 +169,7 @@ func GetDeployment(
 		return nil, err
 	}
 	result := &appsv1.Deployment{}
-	err = shared.Client().Get(
+	err = shared.Get(
 		context.TODO(),
 		types.NamespacedName{Namespace: kdNamespace, Name: deploymentName},
 		result,
@@ -210,7 +210,7 @@ func GetKDConfig(
 	}
 
 	result := &kdv1.KubeDirectorConfig{}
-	err = shared.Client().Get(
+	err = shared.Get(
 		context.TODO(),
 		types.NamespacedName{Namespace: kdNamespace, Name: kdConfigName},
 		result,
@@ -224,7 +224,7 @@ func GetStorageClass(
 ) (*storagev1.StorageClass, error) {
 
 	result := &storagev1.StorageClass{}
-	err := shared.Client().Get(
+	err := shared.Get(
 		context.TODO(),
 		types.NamespacedName{Name: storageClassName},
 		result,
@@ -238,7 +238,7 @@ func GetDefaultStorageClass() (*storagev1.StorageClass, error) {
 
 	// Namespace does not matter for this query; leave blank.
 	result := &storagev1.StorageClassList{}
-	err := shared.Client().List(context.TODO(), &client.ListOptions{}, result)
+	err := shared.List(context.TODO(), &client.ListOptions{}, result)
 	if err != nil {
 		return nil, err
 	}

pkg/shared/client.go

@@ -15,10 +15,14 @@
 package shared
 
 import (
+	"context"
 	"os"
 
 	"github.com/operator-framework/operator-sdk/pkg/k8sutil"
 	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/kubernetes/scheme"
 	typedcorev1 "k8s.io/client-go/kubernetes/typed/core/v1"
@@ -33,9 +37,13 @@ var (
 	// config is a config to talk to the apiserver.
 	config *rest.Config
 
-	// client is a k8s client to perform K8s CRUD operations.
+	// client is a k8s client to perform K8s CRUD operations. Will be set to
+	// the split client (caching reads) after manager startup.
 	client k8sClient.Client
 
+	// directClient is always a non-caching client.
+	directClient k8sClient.Client
+
 	// clientSet is a REST API client that will be used for actions not
 	//     supported through the operator SDK.
 	clientSet kubernetes.Interface
@@ -51,6 +59,7 @@ func init() {
 
 	config = getConfigFromServiceAccount()
 	client = getClient(config)
+	directClient = getClient(config)
 	clientSet = getClientSet(config)
 	eventRecorder = getEventRecorder()
 }
@@ -116,11 +125,6 @@ func Config() *rest.Config {
 	return config
 }
 
-// Client getter ...
-func Client() k8sClient.Client {
-	return client
-}
-
 // SetClient setter ...
 func SetClient(c k8sClient.Client) {
 	client = c
@@ -130,3 +134,77 @@ func SetClient(c k8sClient.Client) {
 func ClientSet() kubernetes.Interface {
 	return clientSet
 }
+
+// Create uses the split client. Should write back directly to K8s, but we'll
+// use the split client in case it ever wants to use the knowledge that we
+// are changing the object.
+func Create(
+	ctx context.Context,
+	obj runtime.Object,
+) error {
+
+	return client.Create(ctx, obj)
+}
+
+// Get will first try a GET through the split client. If this returns 404,
+// it will try the direct client.
+// Cf. https://github.com/bluek8s/kubedirector/issues/267
+func Get(
+	ctx context.Context,
+	key types.NamespacedName,
+	obj runtime.Object,
+) error {
+
+	getErr := client.Get(ctx, key, obj)
+	if (getErr == nil) || (!errors.IsNotFound(getErr)) {
+		return getErr
+	}
+	return directClient.Get(ctx, key, obj)
+}
+
+// List uses the split client. Currently we don't have usecases where we
+// would need to fall back to the direct client if the list has zero items,
+// and it would be somewhat involved to examine the list object here to
+// determine the zero-items case.
+func List(
+	ctx context.Context,
+	opts *k8sClient.ListOptions,
+	list runtime.Object,
+) error {
+
+	return client.List(ctx, opts, list)
+}
+
+// Update uses the split client. Should write back directly to K8s, but we'll
+// use the split client in case it ever wants to use the knowledge that we
+// are changing the object.
+func Update(
+	ctx context.Context,
+	obj runtime.Object,
+) error {
+
+	return client.Update(ctx, obj)
+}
+
+// StatusUpdate uses the split client. Should write back directly to K8s, but
+// we'll use the split client in case it ever wants to use the knowledge that
+// we are changing the object.
+func StatusUpdate(
+	ctx context.Context,
+	obj runtime.Object,
+) error {
+
+	return client.Status().Update(ctx, obj)
+}
+
+// Delete uses the split client. Should write back directly to K8s, but
+// we'll use the split client in case it ever wants to use the knowledge that
+// we are deleting the object.
+func Delete(
+	ctx context.Context,
+	obj runtime.Object,
+	opts ...k8sClient.DeleteOptionFunc,
+) error {
+
+	return client.Delete(ctx, obj, opts...)
+}