Make MergeFrom use strategic merge patch

If you're using Kubernetes, you probably want a strategic merge patch
anyway.  You can always to a merge patch with the manual patch type.

Author: DirectXMan12

pkg/client/client_test.go

@@ -2262,7 +2262,7 @@ var _ = Describe("Patch", func() {
 			patch := client.MergeFrom(cm.DeepCopy())
 
 			By("returning a patch with type MergePatch")
-			Expect(patch.Type()).To(Equal(types.MergePatchType))
+			Expect(patch.Type()).To(Equal(types.StrategicMergePatchType))
 
 			By("retrieving modifying the config map")
 			metav1.SetMetaDataAnnotation(&cm.ObjectMeta, annotationKey, annotationValue)

pkg/client/patch.go

@@ -17,10 +17,10 @@ limitations under the License.
 package client
 
 import (
-	jsonpatch "github.com/evanphx/json-patch"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/json"
+	"k8s.io/apimachinery/pkg/util/strategicpatch"
 )
 
 type patch struct {
@@ -47,9 +47,9 @@ type mergeFromPatch struct {
 	from runtime.Object
 }
 
-// Type implements patch.
+// Type implements Patch.
 func (s *mergeFromPatch) Type() types.PatchType {
-	return types.MergePatchType
+	return types.StrategicMergePatchType
 }
 
 // Data implements Patch.
@@ -64,10 +64,11 @@ func (s *mergeFromPatch) Data(obj runtime.Object) ([]byte, error) {
 		return nil, err
 	}
 
-	return jsonpatch.CreateMergePatch(originalJSON, modifiedJSON)
+	return strategicpatch.CreateTwoWayMergePatch(originalJSON, modifiedJSON, obj)
 }
 
-// MergeFrom creates a Patch that patches using the merge-patch strategy with the given object as base.
+// MergeFrom creates a Patch that patches using the strategic
+// merge-patch strategy with the given object as base.
 func MergeFrom(obj runtime.Object) Patch {
 	return &mergeFromPatch{obj}
 }