pkg/resource: make patching applicator consistent and deprecate update applicator

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

Author: sttts

pkg/resource/api.go

@@ -24,6 +24,7 @@ import (
 	kerrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/types"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
@@ -142,14 +143,34 @@ func (a *APIPatchingApplicator) Apply(ctx context.Context, o client.Object, ao .
 		return errors.Wrap(err, "cannot get object")
 	}
 
+	if d := desired.(metav1.Object); d.GetResourceVersion() != "" && d.GetResourceVersion() != o.GetResourceVersion() {
+		gvr, err := groupResource(a.client, o)
+		if err != nil {
+			return err
+		}
+		return kerrors.NewConflict(gvr, o.GetName(), errors.New("resource version does not match"))
+	}
+
 	for _, fn := range ao {
 		if err := fn(ctx, o, desired); err != nil {
 			return err
 		}
 	}
 
 	// TODO(negz): Allow callers to override the kind of patch used.
-	return errors.Wrap(a.client.Patch(ctx, o, &patch{desired}), "cannot patch object")
+	return errors.Wrap(a.client.Patch(ctx, desired.(client.Object), client.MergeFromWithOptions(o, client.MergeFromWithOptimisticLock{})), "cannot patch object")
+}
+
+func groupResource(c client.Client, o runtime.Object) (schema.GroupResource, error) {
+	gvk, err := c.GroupVersionKindFor(o)
+	if err != nil {
+		return schema.GroupResource{}, errors.Wrapf(err, "cannot determine group version kind of %T", o)
+	}
+	m, err := c.RESTMapper().RESTMapping(gvk.GroupKind(), gvk.Version)
+	if err != nil {
+		return schema.GroupResource{}, errors.Wrapf(err, "cannot determine group resource of %v", gvk)
+	}
+	return m.Resource.GroupResource(), nil
 }
 
 type patch struct{ from runtime.Object }
@@ -165,6 +186,9 @@ type APIUpdatingApplicator struct {
 
 // NewAPIUpdatingApplicator returns an Applicator that applies changes to an
 // object by either creating or updating it in a Kubernetes API server.
+//
+// Deprecated: Use NewAPIPatchingApplicator instead. The updating applicator
+// can lead to data-loss if the Golang types in this process are not up-to-date.
 func NewAPIUpdatingApplicator(c client.Client) *APIUpdatingApplicator {
 	return &APIUpdatingApplicator{client: c}
 }

pkg/resource/resource.go

@@ -231,7 +231,8 @@ func IsConditionTrue(c xpv1.Condition) bool {
 	return c.Status == corev1.ConditionTrue
 }
 
-// An Applicator applies changes to an object.
+// An Applicator applies changes to an object. The passed object is expected to
+// be complete, i.e. not partial.
 type Applicator interface {
 	Apply(context.Context, client.Object, ...ApplyOption) error
 }