⚠️ introduce PatchResponseFromRaw and drop PatchResponse

Author: Mengqi Yu

example/mutatingwebhook.go

@@ -18,6 +18,7 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"net/http"
 
 	corev1 "k8s.io/api/core/v1"
@@ -44,13 +45,18 @@ func (a *podAnnotator) Handle(ctx context.Context, req types.Request) types.Resp
 	if err != nil {
 		return admission.ErrorResponse(http.StatusBadRequest, err)
 	}
-	copy := pod.DeepCopy()
 
-	err = a.mutatePodsFn(ctx, copy)
+	err = a.mutatePodsFn(ctx, pod)
 	if err != nil {
 		return admission.ErrorResponse(http.StatusInternalServerError, err)
 	}
-	return admission.PatchResponse(pod, copy)
+
+	marshaledPod, err := json.Marshal(pod)
+	if err != nil {
+		return admission.ErrorResponse(http.StatusInternalServerError, err)
+	}
+
+	return admission.PatchResponseFromRaw(req.AdmissionRequest.Object.Raw, marshaledPod)
 }
 
 // mutatePodsFn add an annotation to the given pod

pkg/patch/doc.go

@@ -19,10 +19,10 @@ package admission
 import (
 	"net/http"
 
+	"github.com/appscode/jsonpatch"
+
 	admissionv1beta1 "k8s.io/api/admission/v1beta1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-	"k8s.io/apimachinery/pkg/runtime"
-	"sigs.k8s.io/controller-runtime/pkg/patch"
 	"sigs.k8s.io/controller-runtime/pkg/webhook/admission/types"
 )
 
@@ -54,9 +54,11 @@ func ValidationResponse(allowed bool, reason string) types.Response {
 	return resp
 }
 
-// PatchResponse returns a new response with json patch.
-func PatchResponse(original, current runtime.Object) types.Response {
-	patches, err := patch.NewJSONPatch(original, current)
+// PatchResponseFromRaw takes 2 byte arrays and returns a new response with json patch.
+// The original object should be passed in as raw bytes to avoid the roundtripping problem
+// described in https://github.com/kubernetes-sigs/kubebuilder/issues/510.
+func PatchResponseFromRaw(original, current []byte) types.Response {
+	patches, err := jsonpatch.CreatePatch(original, current)
 	if err != nil {
 		return ErrorResponse(http.StatusInternalServerError, err)
 	}

pkg/patch/patch.go

@@ -25,7 +25,6 @@ import (
 	. "github.com/onsi/gomega"
 
 	admissionv1beta1 "k8s.io/api/admission/v1beta1"
-	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"sigs.k8s.io/controller-runtime/pkg/webhook/admission/types"
 )
@@ -72,7 +71,7 @@ var _ = Describe("admission webhook response", func() {
 					PatchType: func() *admissionv1beta1.PatchType { pt := admissionv1beta1.PatchTypeJSONPatch; return &pt }(),
 				},
 			}
-			resp := PatchResponse(&corev1.Pod{}, &corev1.Pod{})
+			resp := PatchResponseFromRaw([]byte(`{}`), []byte(`{}`))
 			Expect(resp).To(Equal(expected))
 		})
 	})