⚠️ Allow setting NewClientFunc w/o re-implementing ClientBuilder

When introducing the ClientBuilder we lost the ability to easily
overwrite the NewClientFunc, this re-adds it.

pkg/cluster/client_builder.go

@@ -29,6 +29,9 @@ type ClientBuilder interface {
 	// for this client. This function can be called multiple times, it should append to an internal slice.
 	WithUncached(objs ...client.Object) ClientBuilder
 
+	// WithNewClientFunc can be used to override the default NewClientFunc.
+	WithNewClientFunc(NewClientFunc) ClientBuilder
+
 	// Build returns a new client.
 	Build(cache cache.Cache, config *rest.Config, options client.Options) (client.Client, error)
 }
@@ -39,16 +42,34 @@ func NewClientBuilder() ClientBuilder {
 }
 
 type newClientBuilder struct {
-	uncached []client.Object
+	uncached      []client.Object
+	newClientFunc NewClientFunc
 }
 
 func (n *newClientBuilder) WithUncached(objs ...client.Object) ClientBuilder {
 	n.uncached = append(n.uncached, objs...)
 	return n
 }
 
+func (n *newClientBuilder) WithNewClientFunc(f NewClientFunc) ClientBuilder {
+	n.newClientFunc = f
+	return n
+}
+
 func (n *newClientBuilder) Build(cache cache.Cache, config *rest.Config, options client.Options) (client.Client, error) {
-	// Create the Client for Write operations.
+	if n.newClientFunc == nil {
+		n.newClientFunc = DefaultNewClientFunc
+	}
+
+	return n.newClientFunc(cache, config, options, n.uncached...)
+}
+
+// NewClientFunc is the signature of the func that is called to construct a new client.
+type NewClientFunc func(cache cache.Cache, config *rest.Config, options client.Options, uncachedObjects ...client.Object) (client.Client, error)
+
+// DefaultNewClientFunc is the default NewClientFunc for the Builder. It's Reader interface
+// is cache-backed.
+func DefaultNewClientFunc(cache cache.Cache, config *rest.Config, options client.Options, uncachedObjects ...client.Object) (client.Client, error) {
 	c, err := client.New(config, options)
 	if err != nil {
 		return nil, err
@@ -57,6 +78,6 @@ func (n *newClientBuilder) Build(cache cache.Cache, config *rest.Config, options
 	return client.NewDelegatingClient(client.NewDelegatingClientInput{
 		CacheReader:     cache,
 		Client:          c,
-		UncachedObjects: n.uncached,
+		UncachedObjects: uncachedObjects,
 	})
 }

pkg/cluster/client_builder_test.go

@@ -0,0 +1,56 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cluster
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/client-go/rest"
+
+	"sigs.k8s.io/controller-runtime/pkg/cache"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+)
+
+type recordingNewClientFunc struct {
+	uncachedObjects []client.Object
+	hasBeenCalled   bool
+}
+
+func (r *recordingNewClientFunc) Func(cache cache.Cache, config *rest.Config, options client.Options, uncachedObjects ...client.Object) (client.Client, error) {
+	r.uncachedObjects = uncachedObjects
+	r.hasBeenCalled = true
+	return nil, nil
+}
+
+var _ = Describe("cluster.ClientBuilder", func() {
+	It("should set new client func", func() {
+		recorder := &recordingNewClientFunc{}
+		_, err := NewClientBuilder().WithNewClientFunc(recorder.Func).Build(nil, nil, client.Options{})
+		Expect(err).NotTo(HaveOccurred())
+		Expect(recorder.hasBeenCalled).To(BeTrue())
+	})
+
+	It("should set uncached objects", func() {
+		recorder := &recordingNewClientFunc{}
+		_, err := NewClientBuilder().WithUncached(&corev1.Pod{}).WithNewClientFunc(recorder.Func).Build(nil, nil, client.Options{})
+		Expect(err).NotTo(HaveOccurred())
+		Expect(recorder.hasBeenCalled).To(BeTrue())
+		Expect(recorder.uncachedObjects).To(Equal([]client.Object{&corev1.Pod{}}))
+	})
+})

pkg/cluster/cluster_test.go

@@ -43,6 +43,10 @@ func (e *fakeClientBuilder) WithUncached(objs ...client.Object) ClientBuilder {
 	return e
 }
 
+func (e *fakeClientBuilder) WithNewClientFunc(f NewClientFunc) ClientBuilder {
+	return e
+}
+
 func (e *fakeClientBuilder) Build(cache cache.Cache, config *rest.Config, options client.Options) (client.Client, error) {
 	return nil, e.err
 }

pkg/manager/manager_test.go

@@ -63,6 +63,10 @@ func (e *fakeClientBuilder) WithUncached(objs ...client.Object) ClientBuilder {
 	return e
 }
 
+func (e *fakeClientBuilder) WithNewClientFunc(f cluster.NewClientFunc) ClientBuilder {
+	return e
+}
+
 func (e *fakeClientBuilder) Build(cache cache.Cache, config *rest.Config, options client.Options) (client.Client, error) {
 	return nil, e.err
 }