pkg/resource: add AdditiveMergePatchApplyOption

Signed-off-by: Dr. Stefan Schimanski <[email protected]>

go.mod

@@ -5,6 +5,7 @@ go 1.20
 require (
 	dario.cat/mergo v1.0.0
 	github.com/bufbuild/buf v1.26.1
+	github.com/evanphx/json-patch v5.6.0+incompatible
 	github.com/go-logr/logr v1.2.4
 	github.com/google/go-cmp v0.5.9
 	github.com/spf13/afero v1.9.5

go.sum

@@ -96,6 +96,7 @@ github.com/envoyproxy/go-control-plane v0.9.7/go.mod h1:cwu0lG7PUMfa9snN8LXBig5y
 github.com/envoyproxy/go-control-plane v0.9.9-0.20201210154907-fd9021fe5dad/go.mod h1:cXg6YxExXjJnVBQHBLXeUAgxn2UodCpnH306RInaBQk=
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
 github.com/evanphx/json-patch v5.6.0+incompatible h1:jBYDEEiFBPxA0v50tFdvOzQQTCvpL6mnFh5mB2/l16U=
+github.com/evanphx/json-patch v5.6.0+incompatible/go.mod h1:50XU6AFN0ol/bzJsmQLiYLvXMP4fmwYFNcr97nuDLSk=
 github.com/evanphx/json-patch/v5 v5.6.0 h1:b91NhWfaz02IuVxO9faSllyAtNXHMPkC5J8sJCLunww=
 github.com/evanphx/json-patch/v5 v5.6.0/go.mod h1:G79N1coSVB93tBe7j6PhzjmR3/2VvlbKOFpnXhI9Bw4=
 github.com/fatih/color v1.15.0 h1:kOqh6YHBtK8aywxGerMG2Eq3H6Qgoqeo13Bk2Mv/nBs=

pkg/resource/api.go

@@ -18,14 +18,19 @@ package resource
 
 import (
 	"context"
+	"encoding/json"
 
+	jsonpatch "github.com/evanphx/json-patch"
 	kerrors "k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/types"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
 	"github.com/crossplane/crossplane-runtime/pkg/errors"
 	"github.com/crossplane/crossplane-runtime/pkg/meta"
+	resourceunstructured "github.com/crossplane/crossplane-runtime/pkg/resource/unstructured"
 )
 
 // Error strings.
@@ -54,7 +59,7 @@ func NewAPIPatchingApplicator(c client.Client) *APIPatchingApplicator {
 // Apply changes to the supplied object. The object will be created if it does
 // not exist, or patched if it does. If the object does exist, it will only be
 // patched if the passed object has the same or an empty resource version.
-func (a *APIPatchingApplicator) Apply(ctx context.Context, obj client.Object, ao ...ApplyOption) error { //nolint:gocyclo // the logic here is crucial and deserves to stay in one method
+func (a *APIPatchingApplicator) Apply(ctx context.Context, obj client.Object, ao ...ApplyOption) error {
 	if obj.GetName() == "" && obj.GetGenerateName() != "" {
 		return a.client.Create(ctx, obj)
 	}
@@ -102,6 +107,41 @@ func groupResource(c client.Client, o client.Object) (schema.GroupResource, erro
 	return m.Resource.GroupResource(), nil
 }
 
+// AdditiveMergePatchApplyOption returns an ApplyOption that makes
+// the Apply additive in the sense of a merge patch without null values. This is
+// the old behavior of the APIPatchingApplicator.
+//
+// This only works with a desired object of type *unstructured.Unstructured.
+//
+// Deprecated: replace with Server Side Apply.
+func AdditiveMergePatchApplyOption(_ context.Context, current, desired runtime.Object) error {
+	u, ok := desired.(*unstructured.Unstructured)
+	if !ok {
+		uw, ok := desired.(resourceunstructured.Wrapper)
+		if !ok {
+			return errors.New("desired object is not an unstructured.Unstructured")
+		}
+		u = uw.GetUnstructured()
+	}
+	currentBytes, err := json.Marshal(current)
+	if err != nil {
+		return errors.Wrapf(err, "cannot marshal current %s", HumanReadableReference(nil, current))
+	}
+	desiredBytes, err := json.Marshal(u)
+	if err != nil {
+		return errors.Wrapf(err, "cannot marshal desired %s", HumanReadableReference(nil, desired))
+	}
+	mergedBytes, err := jsonpatch.MergePatch(currentBytes, desiredBytes)
+	if err != nil {
+		return errors.Wrapf(err, "cannot merge patch to %s", HumanReadableReference(nil, desired))
+	}
+	u.Object = nil
+	if err = json.Unmarshal(mergedBytes, &u.Object); err != nil {
+		return errors.Wrapf(err, "cannot unmarshal merged patch to %s", HumanReadableReference(nil, desired))
+	}
+	return nil
+}
+
 // An APIUpdatingApplicator applies changes to an object by either creating or
 // updating it in a Kubernetes API server.
 type APIUpdatingApplicator struct {

pkg/resource/api_test.go

@@ -18,15 +18,19 @@ package resource
 
 import (
 	"context"
+	"encoding/json"
 	"testing"
 
+	jsonpatch "github.com/evanphx/json-patch"
 	"github.com/google/go-cmp/cmp"
 	kerrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/yaml"
 
 	"github.com/crossplane/crossplane-runtime/pkg/errors"
 	"github.com/crossplane/crossplane-runtime/pkg/resource/fake"
@@ -54,6 +58,14 @@ func TestAPIPatchingApplicator(t *testing.T) {
 	fakeRESTMapper := meta.NewDefaultRESTMapper([]schema.GroupVersion{gvk.GroupVersion()})
 	fakeRESTMapper.AddSpecific(gvk, gvr, singular, meta.RESTScopeRoot)
 
+	// for additive merge patch option test
+	currentYAML := `
+metadata:
+  resourceVersion: "42"
+a: old
+b: old
+`
+
 	type args struct {
 		ctx context.Context
 		o   client.Object
@@ -221,6 +233,63 @@ func TestAPIPatchingApplicator(t *testing.T) {
 				err: kerrors.NewConflict(schema.GroupResource{Group: "example.com", Resource: "things"}, current.GetName(), errors.New(errOptimisticLock)),
 			},
 		},
+		"AdditiveMergePatch": {
+			reason: "No error with the old additive behaviour if desired",
+			c: &test.MockClient{
+				MockGet: test.NewMockGetFn(nil, func(o client.Object) error {
+					o.(*unstructured.Unstructured).Object = map[string]interface{}{}
+					return yaml.Unmarshal([]byte(currentYAML), &o.(*unstructured.Unstructured).Object)
+				}),
+				MockPatch: func(_ context.Context, o client.Object, patch client.Patch, _ ...client.PatchOption) error {
+					bs, err := patch.Data(o)
+					if err != nil {
+						return err
+					}
+					currentJSON, err := yaml.YAMLToJSON([]byte(currentYAML))
+					if err != nil {
+						return err
+					}
+					patched, err := jsonpatch.MergePatch(currentJSON, bs)
+					if err != nil {
+						return err
+					}
+					o.(*unstructured.Unstructured).Object = map[string]interface{}{}
+					if err := json.Unmarshal(patched, &o.(*unstructured.Unstructured).Object); err != nil {
+						return err
+					}
+					o.SetResourceVersion("43")
+					return nil
+				},
+				MockGroupVersionKindFor: test.NewMockGroupVersionKindForFn(nil, gvk),
+				MockRESTMapper:          test.NewMockRESTMapperFn(fakeRESTMapper),
+			},
+			args: args{
+				o: &unstructured.Unstructured{
+					Object: map[string]interface{}{
+						"kind": "Thing",
+						"metadata": map[string]interface{}{
+							"resourceVersion": "42",
+						},
+						"b": "changed",
+						"c": "added",
+					},
+				},
+				ao: []ApplyOption{AdditiveMergePatchApplyOption},
+			},
+			want: want{
+				o: &unstructured.Unstructured{
+					Object: map[string]interface{}{
+						"kind": "Thing",
+						"metadata": map[string]interface{}{
+							"resourceVersion": "43",
+						},
+						"a": "old",
+						"b": "changed",
+						"c": "added",
+					},
+				},
+			},
+		},
 	}
 
 	for name, tc := range cases {