fixup! Extract out multi-handler support, remove builder

Author: DirectXMan12

pkg/webhook/admission/webhook.go

@@ -19,11 +19,17 @@ package admission
 import (
 	"context"
 	"net/http"
+	"errors"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"sigs.k8s.io/controller-runtime/pkg/runtime/inject"
 	"github.com/appscode/jsonpatch"
 	admissionv1beta1 "k8s.io/api/admission/v1beta1"
+	"k8s.io/apimachinery/pkg/util/json"
+)
+
+var (
+	unableToEncodeResponse = errors.New("unable to encode response")
 )
 
 // Request defines the input for an admission handler.
@@ -43,12 +49,44 @@ type Response struct {
 	// Patches are the JSON patches for mutating webhooks.
 	// Using this instead of setting Response.Patch to minimize
 	// overhead of serialization and deserialization.
+	// Patches set here will override any patches in the response,
+	// so leave this empty if you want to set the patch response directly.
 	Patches []jsonpatch.JsonPatchOperation
 	// AdmissionResponse is the raw admission response.
 	// The Patch field in it will be overwritten by the listed patches.
 	admissionv1beta1.AdmissionResponse
 }
 
+// Complete populates any fields that are yet to be set in
+// the underlying AdmissionResponse, It mutates the response.
+func (r *Response) Complete(req Request) error {
+	r.UID = req.UID
+
+	// ensure that we have a valid status code
+	if r.Result == nil {
+		r.Result = &metav1.Status{}
+	}
+	if r.Result.Code == 0 {
+		r.Result.Code = http.StatusOK
+	}
+	// TODO(directxman12): do we need to populate this further, and/or
+	// is code actually necessary (the same webhook doesn't use it)
+
+	if len(r.Patches) == 0 {
+		return nil
+	}
+
+	var err error
+	r.Patch, err = json.Marshal(r.Patches)
+	if err != nil {
+		return err
+	}
+	patchType := admissionv1beta1.PatchTypeJSONPatch
+	r.PatchType = &patchType
+
+	return nil
+}
+
 // Handler can handle an AdmissionRequest.
 type Handler interface {
 	Handle(context.Context, Request) Response
@@ -77,17 +115,10 @@ type Webhook struct {
 // deny the request if anyone denies.
 func (w *Webhook) Handle(ctx context.Context, req Request) Response {
 	resp := w.Handler.Handle(ctx, req)
-	resp.UID = req.UID
-
-	// ensure that we have a valid status code
-	if resp.Result == nil {
-		resp.Result = &metav1.Status{}
-	}
-	if resp.Result.Code == 0 {
-		resp.Result.Code = http.StatusOK
+	if err := resp.Complete(req); err != nil {
+		log.Error(err, "unable to encode response")
+		return ErrorResponse(http.StatusInternalServerError, unableToEncodeResponse)
 	}
-	// TODO(directxman12): do we need to populate this further, and/or
-	// is code actually necessary (the same webhook doesn't use it)
 
 	return resp
 }