🐛 skip mutation handler when received deletion verb

pkg/webhook/admission/defaulter.go

@@ -21,6 +21,8 @@ import (
 	"encoding/json"
 	"net/http"
 
+	admissionv1 "k8s.io/api/admission/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 )
 
@@ -56,6 +58,17 @@ func (h *mutatingHandler) Handle(ctx context.Context, req Request) Response {
 		panic("defaulter should never be nil")
 	}
 
+	// always skip when a DELETE operation received in mutation handler
+	// describe in https://github.com/kubernetes-sigs/controller-runtime/issues/1762
+	if req.Operation == admissionv1.Delete {
+		return Response{AdmissionResponse: admissionv1.AdmissionResponse{
+			Allowed: true,
+			Result: &metav1.Status{
+				Code: http.StatusOK,
+			},
+		}}
+	}
+
 	// Get the object in the request
 	obj := h.defaulter.DeepCopyObject().(Defaulter)
 	if err := h.decoder.Decode(req, obj); err != nil {

pkg/webhook/admission/defaulter_test.go

@@ -0,0 +1,68 @@
+package admission
+
+import (
+	"context"
+	"net/http"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	admissionv1 "k8s.io/api/admission/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+)
+
+var _ = Describe("Defaulter Handler", func() {
+
+	It("should return ok if received delete verb in defaulter handler", func() {
+		obj := &TestDefaulter{}
+		handler := DefaultingWebhookFor(obj)
+
+		resp := handler.Handle(context.TODO(), Request{
+			AdmissionRequest: admissionv1.AdmissionRequest{
+				Operation: admissionv1.Delete,
+				OldObject: runtime.RawExtension{
+					Raw: []byte("{}"),
+				},
+			},
+		})
+		Expect(resp.Allowed).Should(BeTrue())
+		Expect(resp.Result.Code).Should(Equal(int32(http.StatusOK)))
+	})
+
+})
+
+// TestDefaulter.
+var _ runtime.Object = &TestDefaulter{}
+
+type TestDefaulter struct {
+	Replica int `json:"replica,omitempty"`
+}
+
+var testDefaulterGVK = schema.GroupVersionKind{Group: "foo.test.org", Version: "v1", Kind: "TestDefaulter"}
+
+func (d *TestDefaulter) GetObjectKind() schema.ObjectKind { return d }
+func (d *TestDefaulter) DeepCopyObject() runtime.Object {
+	return &TestDefaulter{
+		Replica: d.Replica,
+	}
+}
+
+func (d *TestDefaulter) GroupVersionKind() schema.GroupVersionKind {
+	return testDefaulterGVK
+}
+
+func (d *TestDefaulter) SetGroupVersionKind(gvk schema.GroupVersionKind) {}
+
+var _ runtime.Object = &TestDefaulterList{}
+
+type TestDefaulterList struct{}
+
+func (*TestDefaulterList) GetObjectKind() schema.ObjectKind { return nil }
+func (*TestDefaulterList) DeepCopyObject() runtime.Object   { return nil }
+
+func (d *TestDefaulter) Default() {
+	if d.Replica < 2 {
+		d.Replica = 2
+	}
+}