✨ Add client.StrategicMergeFrom

pkg/client/client_test.go

@@ -3240,7 +3240,7 @@ var _ = Describe("DelegatingClient", func() {
 })
 
 var _ = Describe("Patch", func() {
-	Describe("CreateMergePatch", func() {
+	Describe("MergeFrom", func() {
 		var cm *corev1.ConfigMap
 
 		BeforeEach(func() {
@@ -3303,6 +3303,98 @@ var _ = Describe("Patch", func() {
 			Expect(data).To(Equal([]byte(fmt.Sprintf(`{"metadata":{"annotations":{"%s":"%s"},"resourceVersion":"%s"}}`, annotationKey, annotationValue, cm.ResourceVersion))))
 		})
 	})
+
+	Describe("StrategicMergeFrom", func() {
+		var dep *appsv1.Deployment
+
+		BeforeEach(func() {
+			dep = &appsv1.Deployment{
+				ObjectMeta: metav1.ObjectMeta{
+					Namespace:       metav1.NamespaceDefault,
+					Name:            "dep",
+					ResourceVersion: "10",
+				},
+				Spec: appsv1.DeploymentSpec{
+					Template: corev1.PodTemplateSpec{
+						Spec: corev1.PodSpec{Containers: []corev1.Container{{
+							Name:  "main",
+							Image: "foo:v1",
+						}, {
+							Name:  "sidecar",
+							Image: "bar:v1",
+						}}},
+					},
+				},
+			}
+		})
+
+		It("creates a strategic merge patch with the modifications applied during the mutation", func() {
+			By("creating a strategic merge patch")
+			patch := client.StrategicMergeFrom(dep.DeepCopy())
+
+			By("returning a patch with type StrategicMergePatchType")
+			Expect(patch.Type()).To(Equal(types.StrategicMergePatchType))
+
+			By("updating the main container's image")
+			for i, c := range dep.Spec.Template.Spec.Containers {
+				if c.Name == "main" {
+					c.Image = "foo:v2"
+				}
+				dep.Spec.Template.Spec.Containers[i] = c
+			}
+
+			By("computing the patch data")
+			data, err := patch.Data(dep)
+
+			By("returning no error")
+			Expect(err).NotTo(HaveOccurred())
+
+			By("returning a patch with data only containing the image change")
+			Expect(data).To(Equal([]byte(`{"spec":{"template":{"spec":{"$setElementOrder/containers":[{"name":"main"},` +
+				`{"name":"sidecar"}],"containers":[{"image":"foo:v2","name":"main"}]}}}}`)))
+		})
+
+		It("creates a strategic merge patch with the modifications applied during the mutation, using optimistic locking", func() {
+			By("creating a strategic merge patch")
+			patch := client.StrategicMergeFromWithOptions(dep.DeepCopy(), client.MergeFromWithOptimisticLock{})
+
+			By("returning a patch with type StrategicMergePatchType")
+			Expect(patch.Type()).To(Equal(types.StrategicMergePatchType))
+
+			By("updating the main container's image")
+			for i, c := range dep.Spec.Template.Spec.Containers {
+				if c.Name == "main" {
+					c.Image = "foo:v2"
+				}
+				dep.Spec.Template.Spec.Containers[i] = c
+			}
+
+			By("computing the patch data")
+			data, err := patch.Data(dep)
+
+			By("returning no error")
+			Expect(err).NotTo(HaveOccurred())
+
+			By("returning a patch with data containing the image change and the resourceVersion change")
+			Expect(data).To(Equal([]byte(fmt.Sprintf(`{"metadata":{"resourceVersion":"%s"},`+
+				`"spec":{"template":{"spec":{"$setElementOrder/containers":[{"name":"main"},{"name":"sidecar"}],"containers":[{"image":"foo:v2","name":"main"}]}}}}`,
+				dep.ResourceVersion))))
+		})
+
+		It("fails if the resourceVersion was changed", func() {
+			By("creating a strategic merge patch")
+			patch := client.StrategicMergeFromWithOptions(dep.DeepCopy(), client.MergeFromWithOptimisticLock{})
+
+			By("updating the resourceVersion")
+			dep.SetResourceVersion("42")
+
+			By("computing the patch data")
+			_, err := patch.Data(dep)
+
+			By("returning no error")
+			Expect(err).To(MatchError(ContainSubstring("precondition failed")))
+		})
+	})
 })
 
 var _ = Describe("IgnoreNotFound", func() {

pkg/client/patch.go

@@ -25,6 +25,8 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/json"
+	"k8s.io/apimachinery/pkg/util/mergepatch"
+	"k8s.io/apimachinery/pkg/util/strategicpatch"
 )
 
 var (
@@ -184,3 +186,72 @@ func (p applyPatch) Data(obj runtime.Object) ([]byte, error) {
 	// client-go does, more-or-less).
 	return json.Marshal(obj)
 }
+
+type strategicMergeFromPatch struct {
+	from runtime.Object
+	opts MergeFromOptions
+}
+
+// Type implements patch.
+func (s *strategicMergeFromPatch) Type() types.PatchType {
+	return types.StrategicMergePatchType
+}
+
+// Data implements Patch.
+func (s *strategicMergeFromPatch) Data(obj runtime.Object) ([]byte, error) {
+	originalJSON, err := json.Marshal(s.from)
+	if err != nil {
+		return nil, err
+	}
+
+	modifiedJSON, err := json.Marshal(obj)
+	if err != nil {
+		return nil, err
+	}
+
+	preconditions := []mergepatch.PreconditionFunc{
+		mergepatch.RequireMetadataKeyUnchanged("resourceVersion"),
+	}
+
+	data, err := strategicpatch.CreateTwoWayMergePatch(originalJSON, modifiedJSON, obj, preconditions...)
+	if err != nil {
+		return nil, err
+	}
+
+	if s.opts.OptimisticLock {
+		dataMap := map[string]interface{}{}
+		if err := json.Unmarshal(data, &dataMap); err != nil {
+			return nil, err
+		}
+		fromMeta, ok := s.from.(metav1.Object)
+		if !ok {
+			return nil, fmt.Errorf("cannot use OptimisticLock, from object %q is not a valid metav1.Object", s.from)
+		}
+		resourceVersion := fromMeta.GetResourceVersion()
+		if len(resourceVersion) == 0 {
+			return nil, fmt.Errorf("cannot use OptimisticLock, from object %q does not have any resource version we can use", s.from)
+		}
+		u := &unstructured.Unstructured{Object: dataMap}
+		u.SetResourceVersion(resourceVersion)
+		data, err = json.Marshal(u)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return data, nil
+}
+
+// StrategicMergeFrom creates a Patch that patches using the strategic-merge-patch strategy with the given object as base.
+func StrategicMergeFrom(obj runtime.Object) Patch {
+	return &strategicMergeFromPatch{from: obj}
+}
+
+// StrategicMergeFromWithOptions creates a Patch that patches using the strategic-merge-patch strategy with the given object as base.
+func StrategicMergeFromWithOptions(obj runtime.Object, opts ...MergeFromOption) Patch {
+	options := &MergeFromOptions{}
+	for _, opt := range opts {
+		opt.ApplyToMergeFrom(options)
+	}
+	return &strategicMergeFromPatch{from: obj, opts: *options}
+}