Use object in cluster for basis for three way merge instead of new object

This change modifies the merge strategy to use the object in the
basis for the patch rather than the modified object. This allows
the three way merge to detect changes in the new object.
Signed-off-by: bryanl <bryanliles@gmail.com>

pkg/cluster/merger.go

@@ -124,7 +124,7 @@ func (p *defaultObjectMerger) Merge(namespace string, obj *unstructured.Unstruct
 		}
 	}
 
-	modified, err := runtime.Encode(encoder, info.Object)
+	modified, err := runtime.Encode(encoder, obj)
 	if err != nil {
 		return nil, errors.Wrap(err, "encode modified object")
 	}
@@ -257,7 +257,8 @@ func (p *patcher) patchSimple(obj runtime.Object, modified []byte, source, names
 		if p.openapiSchema != nil {
 			if schema = p.openapiSchema.LookupResource(p.mapping.GroupVersionKind); schema != nil {
 				lookupPatchMeta = strategicpatch.PatchMetaFromOpenAPI{Schema: schema}
-				if openapiPatch, err := strategicpatch.CreateThreeWayMergePatch(original, modified, current, lookupPatchMeta, p.overwrite); err != nil {
+				openapiPatch, err := strategicpatch.CreateThreeWayMergePatch(original, modified, current, lookupPatchMeta, p.overwrite)
+				if err != nil {
 					fmt.Fprintf(errOut, "warning: error calculating patch from openapi spec: %v\n", err)
 				} else {
 					patchType = types.StrategicMergePatchType

pkg/cluster/merger_test.go

@@ -77,6 +77,8 @@ func Test_merger_merge(t *testing.T) {
 		},
 	}
 
+	isPatched := false
+
 	tf.UnstructuredClient = &fake.RESTClient{
 		NegotiatedSerializer: unstructuredSerializer,
 		Client: fake.CreateHTTPClient(func(req *http.Request) (*http.Response, error) {
@@ -88,6 +90,8 @@ func Test_merger_merge(t *testing.T) {
 				_, err := convertToObject(req.Body)
 				require.NoError(t, err)
 
+				isPatched = true
+
 				return &http.Response{StatusCode: 200, Header: defaultHeader(), Body: objBody(codec, clusterService)}, nil
 			default:
 				t.Fatalf("unexpected request using unstructured client: %#v\n%#v", req.URL, req)
@@ -148,6 +152,8 @@ func Test_merger_merge(t *testing.T) {
 
 	_, err := om.Merge("testing", obj)
 	require.NoError(t, err)
+
+	require.True(t, isPatched)
 }
 
 type fakeObjectMerger struct {