什么是resthandler

之前已经分析到，Kubernetes是如何注册API的。Kubernetes会把对应路径上的请求交给对应的resthandler处理。所以，resthandler是对请求进行处理并响应的函数。在Kubernetes中，给每一种动作设置了对应的resthandler，如下表格所示(只列出了主要部分)：

动作 函数
GET GetResource
LIST ListResource
PUT UpdateResource
PATCH PatchResource
POST CreateResource
DELETE DeleteResource
WATCH ListResource

GetResource()

GetResource()定义在/pkg/apiserver/resthandler.go中：

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// GetResource returns a function that handles retrieving a single resource from a rest.Storage object.
func GetResource(r rest.Getter, e rest.Exporter, scope RequestScope) restful.RouteFunction {
	return getResourceHandler(scope,
		func(ctx api.Context, name string, req *restful.Request) (runtime.Object, error) {
			// For performance tracking purposes.
			trace := util.NewTrace("Get " + req.Request.URL.Path)
			defer trace.LogIfLong(500 * time.Millisecond)
			// check for export
			if values := req.Request.URL.Query(); len(values) > 0 {
				// TODO: this is internal version, not unversioned
				exports := unversioned.ExportOptions{}
				if err := scope.ParameterCodec.DecodeParameters(values, unversioned.GroupVersion{Version: "v1"}, &exports); err != nil {
					return nil, err
				}
				if exports.Export {
					if e == nil {
						return nil, errors.NewBadRequest(fmt.Sprintf("export of %q is not supported", scope.Resource.Resource))
					}
					return e.Export(ctx, name, exports)
				}
			}
			return r.Get(ctx, name)
		})
}

GetResource()中定义了获取资源的函数，然后通过getResourceHandler()进行封装。

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// getResourceHandler is an HTTP handler function for get requests. It delegates to the
// passed-in getterFunc to perform the actual get.
func getResourceHandler(scope RequestScope, getter getterFunc) restful.RouteFunction {
	return func(req *restful.Request, res *restful.Response) {
		w := res.ResponseWriter
		namespace, name, err := scope.Namer.Name(req)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		ctx := scope.ContextFunc(req)
		ctx = api.WithNamespace(ctx, namespace)
		//***调用getterFunc，获取result***//
		result, err := getter(ctx, name, req)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		if err := setSelfLink(result, req, scope.Namer); err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		write(http.StatusOK, scope.Kind.GroupVersion(), scope.Serializer, result, w, req.Request)
	}
}

getResourceHandler()先从Request中获取namespace和name，然后namespace封装到ctx中，最后调用GetResource()中定义的获取资源的函数，获取到资源后，把结果写入请求的应答体。

ListResource()

ListResource()用来获取资源列表。

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// ListResource returns a function that handles retrieving a list of resources from a rest.Storage object.
func ListResource(r rest.Lister, rw rest.Watcher, scope RequestScope, forceWatch bool, minRequestTimeout time.Duration) restful.RouteFunction {
	return func(req *restful.Request, res *restful.Response) {
		// For performance tracking purposes.
		trace := util.NewTrace("List " + req.Request.URL.Path)
		w := res.ResponseWriter
		//***获取namespace***//
		namespace, err := scope.Namer.Namespace(req)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		// Watches for single objects are routed to this function.
		// Treat a /name parameter the same as a field selector entry.
		hasName := true
		_, name, err := scope.Namer.Name(req)
		if err != nil {
			hasName = false
		}
		ctx := scope.ContextFunc(req)
		//***设置namespace key***//
		ctx = api.WithNamespace(ctx, namespace)
		opts := api.ListOptions{}
		if err := scope.ParameterCodec.DecodeParameters(req.Request.URL.Query(), scope.Kind.GroupVersion(), &opts); err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		// transform fields
		// TODO: DecodeParametersInto should do this.
		if opts.FieldSelector != nil {
			fn := func(label, value string) (newLabel, newValue string, err error) {
				return scope.Convertor.ConvertFieldLabel(scope.Kind.GroupVersion().String(), scope.Kind.Kind, label, value)
			}
			if opts.FieldSelector, err = opts.FieldSelector.Transform(fn); err != nil {
				// TODO: allow bad request to set field causes based on query parameters
				err = errors.NewBadRequest(err.Error())
				scope.err(err, res.ResponseWriter, req.Request)
				return
			}
		}
		if hasName {
			// metadata.name is the canonical internal name.
			// SelectionPredicate will notice that this is
			// a request for a single object and optimize the
			// storage query accordingly.
			nameSelector := fields.OneTermEqualSelector("metadata.name", name)
			if opts.FieldSelector != nil && !opts.FieldSelector.Empty() {
				// It doesn't make sense to ask for both a name
				// and a field selector, since just the name is
				// sufficient to narrow down the request to a
				// single object.
				scope.err(errors.NewBadRequest("both a name and a field selector provided; please provide one or the other."), res.ResponseWriter, req.Request)
				return
			}
			opts.FieldSelector = nameSelector
		}
		if (opts.Watch || forceWatch) && rw != nil {
			watcher, err := rw.Watch(ctx, &opts)
			if err != nil {
				scope.err(err, res.ResponseWriter, req.Request)
				return
			}
			// TODO: Currently we explicitly ignore ?timeout= and use only ?timeoutSeconds=.
			timeout := time.Duration(0)
			if opts.TimeoutSeconds != nil {
				timeout = time.Duration(*opts.TimeoutSeconds) * time.Second
			}
			if timeout == 0 && minRequestTimeout > 0 {
				timeout = time.Duration(float64(minRequestTimeout) * (rand.Float64() + 1.0))
			}
			serveWatch(watcher, scope, req, res, timeout)
			return
		}
		// Log only long List requests (ignore Watch).
		defer trace.LogIfLong(500 * time.Millisecond)
		trace.Step("About to List from storage")
		//***获取list result***//
		result, err := r.List(ctx, &opts)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		trace.Step("Listing from storage done")
		numberOfItems, err := setListSelfLink(result, req, scope.Namer)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		trace.Step("Self-linking done")
		write(http.StatusOK, scope.Kind.GroupVersion(), scope.Serializer, result, w, req.Request)
		trace.Step(fmt.Sprintf("Writing http response done (%d items)", numberOfItems))
	}
}

如果执行的是WATCH动作，则会调用serveWatch()，定义在/pkg/apiserver/watch.go中：

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//***Watch()实现函数***//
func serveWatch(watcher watch.Interface, scope RequestScope, req *restful.Request, res *restful.Response, timeout time.Duration) {
	// negotiate for the stream serializer
	serializer, err := negotiateOutputStreamSerializer(req.Request, scope.Serializer)
	if err != nil {
		scope.err(err, res.ResponseWriter, req.Request)
		return
	}
	framer := serializer.StreamSerializer.Framer
	streamSerializer := serializer.StreamSerializer.Serializer
	embedded := serializer.Serializer
	if framer == nil {
		scope.err(fmt.Errorf("no framer defined for %q available for embedded encoding", serializer.MediaType), res.ResponseWriter, req.Request)
		return
	}
	encoder := scope.Serializer.EncoderForVersion(streamSerializer, scope.Kind.GroupVersion())
	useTextFraming := serializer.EncodesAsText
	// find the embedded serializer matching the media type
	embeddedEncoder := scope.Serializer.EncoderForVersion(embedded, scope.Kind.GroupVersion())
	// TODO: next step, get back mediaTypeOptions from negotiate and return the exact value here
	mediaType := serializer.MediaType
	if mediaType != runtime.ContentTypeJSON {
		mediaType += ";stream=watch"
	}
	server := &WatchServer{
		watching: watcher,
		scope:    scope,
		useTextFraming:  useTextFraming,
		mediaType:       mediaType,
		framer:          framer,
		encoder:         encoder,
		embeddedEncoder: embeddedEncoder,
		fixup: func(obj runtime.Object) {
			if err := setSelfLink(obj, req, scope.Namer); err != nil {
				utilruntime.HandleError(fmt.Errorf("failed to set link for object %v: %v", reflect.TypeOf(obj), err))
			}
		},
		t: &realTimeoutFactory{timeout},
	}
	server.ServeHTTP(res.ResponseWriter, req.Request)
}

关于List和Watch的操作，以后会在专题进行分析。

UpdateResource()

UpdateResource()用于处理更新资源人请求。

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// UpdateResource returns a function that will handle a resource update
func UpdateResource(r rest.Updater, scope RequestScope, typer runtime.ObjectTyper, admit admission.Interface) restful.RouteFunction {
	return func(req *restful.Request, res *restful.Response) {
		// For performance tracking purposes.
		trace := util.NewTrace("Update " + req.Request.URL.Path)
		defer trace.LogIfLong(500 * time.Millisecond)
		w := res.ResponseWriter
		// TODO: we either want to remove timeout or document it (if we document, move timeout out of this function and declare it in api_installer)
		timeout := parseTimeout(req.Request.URL.Query().Get("timeout"))
		//***从Request中获取namespace, name***//
		namespace, name, err := scope.Namer.Name(req)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		//***创建context，并封装入namespace***//
		ctx := scope.ContextFunc(req)
		ctx = api.WithNamespace(ctx, namespace)
		body, err := readBody(req.Request)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		s, err := negotiateInputSerializer(req.Request, scope.Serializer)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		defaultGVK := scope.Kind
		original := r.New()
		trace.Step("About to convert to expected version")
		obj, gvk, err := scope.Serializer.DecoderToVersion(s.Serializer, defaultGVK.GroupVersion()).Decode(body, &defaultGVK, original)
		if err != nil {
			err = transformDecodeError(typer, err, original, gvk, body)
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		if gvk.GroupVersion() != defaultGVK.GroupVersion() {
			err = errors.NewBadRequest(fmt.Sprintf("the API version in the data (%s) does not match the expected API version (%s)", gvk.GroupVersion(), defaultGVK.GroupVersion()))
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		trace.Step("Conversion done")
		if err := checkName(obj, name, namespace, scope.Namer); err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		var transformers []rest.TransformFunc
		if admit != nil && admit.Handles(admission.Update) {
			transformers = append(transformers, func(ctx api.Context, newObj, oldObj runtime.Object) (runtime.Object, error) {
				userInfo, _ := api.UserFrom(ctx)
				return newObj, admit.Admit(admission.NewAttributesRecord(newObj, oldObj, scope.Kind, namespace, name, scope.Resource, scope.Subresource, admission.Update, userInfo))
			})
		}
		trace.Step("About to store object in database")
		wasCreated := false
		result, err := finishRequest(timeout, func() (runtime.Object, error) {
			//***更新资源***//
			obj, created, err := r.Update(ctx, name, rest.DefaultUpdatedObjectInfo(obj, scope.Copier, transformers...))
			wasCreated = created
			return obj, err
		})
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		trace.Step("Object stored in database")
		if err := setSelfLink(result, req, scope.Namer); err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		trace.Step("Self-link added")
		status := http.StatusOK
		if wasCreated {
			status = http.StatusCreated
		}
		write(status, scope.Kind.GroupVersion(), scope.Serializer, result, w, req.Request)
	}
}

PatchResource()

用来处理局部更新的请求。

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// PatchResource returns a function that will handle a resource patch
// TODO: Eventually PatchResource should just use GuaranteedUpdate and this routine should be a bit cleaner
func PatchResource(r rest.Patcher, scope RequestScope, typer runtime.ObjectTyper, admit admission.Interface, converter runtime.ObjectConvertor) restful.RouteFunction {
	return func(req *restful.Request, res *restful.Response) {
		w := res.ResponseWriter
		// TODO: we either want to remove timeout or document it (if we
		// document, move timeout out of this function and declare it in
		// api_installer)
		timeout := parseTimeout(req.Request.URL.Query().Get("timeout"))
		namespace, name, err := scope.Namer.Name(req)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		ctx := scope.ContextFunc(req)
		ctx = api.WithNamespace(ctx, namespace)
		versionedObj, err := converter.ConvertToVersion(r.New(), scope.Kind.GroupVersion())
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		// TODO: handle this in negotiation
		contentType := req.HeaderParameter("Content-Type")
		// Remove "; charset=" if included in header.
		if idx := strings.Index(contentType, ";"); idx > 0 {
			contentType = contentType[:idx]
		}
		patchType := api.PatchType(contentType)
		patchJS, err := readBody(req.Request)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		s, ok := runtime.SerializerInfoForMediaType(scope.Serializer.SupportedMediaTypes(), runtime.ContentTypeJSON)
		if !ok {
			scope.err(fmt.Errorf("no serializer defined for JSON"), res.ResponseWriter, req.Request)
			return
		}
		gv := scope.Kind.GroupVersion()
		codec := runtime.NewCodec(
			scope.Serializer.EncoderForVersion(s.Serializer, gv),
			scope.Serializer.DecoderToVersion(s.Serializer, unversioned.GroupVersion{Group: gv.Group, Version: runtime.APIVersionInternal}),
		)
		updateAdmit := func(updatedObject runtime.Object, currentObject runtime.Object) error {
			if admit != nil && admit.Handles(admission.Update) {
				userInfo, _ := api.UserFrom(ctx)
				return admit.Admit(admission.NewAttributesRecord(updatedObject, currentObject, scope.Kind, namespace, name, scope.Resource, scope.Subresource, admission.Update, userInfo))
			}
			return nil
		}
		result, err := patchResource(ctx, updateAdmit, timeout, versionedObj, r, name, patchType, patchJS, scope.Namer, scope.Copier, scope.Resource, codec)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		if err := setSelfLink(result, req, scope.Namer); err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		write(http.StatusOK, scope.Kind.GroupVersion(), scope.Serializer, result, w, req.Request)
	}
}

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// patchResource divides PatchResource for easier unit testing
func patchResource(
	ctx api.Context,
	admit updateAdmissionFunc,
	timeout time.Duration,
	versionedObj runtime.Object,
	patcher rest.Patcher,
	name string,
	patchType api.PatchType,
	patchJS []byte,
	namer ScopeNamer,
	copier runtime.ObjectCopier,
	resource unversioned.GroupVersionResource,
	codec runtime.Codec,
) (runtime.Object, error) {
	namespace := api.NamespaceValue(ctx)
	var (
		originalObjJS        []byte
		originalPatchedObjJS []byte
		lastConflictErr      error
	)
	// applyPatch is called every time GuaranteedUpdate asks for the updated object,
	// and is given the currently persisted object as input.
	applyPatch := func(_ api.Context, _, currentObject runtime.Object) (runtime.Object, error) {
		// Make sure we actually have a persisted currentObject
		if hasUID, err := hasUID(currentObject); err != nil {
			return nil, err
		} else if !hasUID {
			return nil, errors.NewNotFound(resource.GroupResource(), name)
		}
		switch {
		case len(originalObjJS) == 0 || len(originalPatchedObjJS) == 0:
			// first time through,
			// 1. apply the patch
			// 2. save the originalJS and patchedJS to detect whether there were conflicting changes on retries
			if js, err := runtime.Encode(codec, currentObject); err != nil {
				return nil, err
			} else {
				originalObjJS = js
			}
			if js, err := getPatchedJS(patchType, originalObjJS, patchJS, versionedObj); err != nil {
				return nil, err
			} else {
				originalPatchedObjJS = js
			}
			objToUpdate := patcher.New()
			if err := runtime.DecodeInto(codec, originalPatchedObjJS, objToUpdate); err != nil {
				return nil, err
			}
			if err := checkName(objToUpdate, name, namespace, namer); err != nil {
				return nil, err
			}
			return objToUpdate, nil
		default:
			// on a conflict,
			// 1. build a strategic merge patch from originalJS and the patchedJS.  Different patch types can
			//    be specified, but a strategic merge patch should be expressive enough handle them.  Build the
			//    patch with this type to handle those cases.
			// 2. build a strategic merge patch from originalJS and the currentJS
			// 3. ensure no conflicts between the two patches
			// 4. apply the #1 patch to the currentJS object
			currentObjectJS, err := runtime.Encode(codec, currentObject)
			if err != nil {
				return nil, err
			}
			currentPatch, err := strategicpatch.CreateStrategicMergePatch(originalObjJS, currentObjectJS, versionedObj)
			if err != nil {
				return nil, err
			}
			originalPatch, err := strategicpatch.CreateStrategicMergePatch(originalObjJS, originalPatchedObjJS, versionedObj)
			if err != nil {
				return nil, err
			}
			diff1 := make(map[string]interface{})
			if err := json.Unmarshal(originalPatch, &diff1); err != nil {
				return nil, err
			}
			diff2 := make(map[string]interface{})
			if err := json.Unmarshal(currentPatch, &diff2); err != nil {
				return nil, err
			}
			hasConflicts, err := strategicpatch.HasConflicts(diff1, diff2)
			if err != nil {
				return nil, err
			}
			if hasConflicts {
				glog.V(4).Infof("patchResource failed for resource %s, because there is a meaningful conflict.\n diff1=%v\n, diff2=%v\n", name, diff1, diff2)
				// Return the last conflict error we got if we have one
				if lastConflictErr != nil {
					return nil, lastConflictErr
				}
				// Otherwise manufacture one of our own
				return nil, errors.NewConflict(resource.GroupResource(), name, nil)
			}
			newlyPatchedObjJS, err := getPatchedJS(api.StrategicMergePatchType, currentObjectJS, originalPatch, versionedObj)
			if err != nil {
				return nil, err
			}
			objToUpdate := patcher.New()
			if err := runtime.DecodeInto(codec, newlyPatchedObjJS, objToUpdate); err != nil {
				return nil, err
			}
			return objToUpdate, nil
		}
	}
	// applyAdmission is called every time GuaranteedUpdate asks for the updated object,
	// and is given the currently persisted object and the patched object as input.
	applyAdmission := func(ctx api.Context, patchedObject runtime.Object, currentObject runtime.Object) (runtime.Object, error) {
		return patchedObject, admit(patchedObject, currentObject)
	}
	updatedObjectInfo := rest.DefaultUpdatedObjectInfo(nil, copier, applyPatch, applyAdmission)
	return finishRequest(timeout, func() (runtime.Object, error) {
		updateObject, _, updateErr := patcher.Update(ctx, name, updatedObjectInfo)
		for i := 0; i < MaxPatchConflicts && (errors.IsConflict(updateErr)); i++ {
			lastConflictErr = updateErr
			updateObject, _, updateErr = patcher.Update(ctx, name, updatedObjectInfo)
		}
		return updateObject, updateErr
	})
}

CreateResource()

CreateResource()用来处理创建的请求。

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// CreateResource returns a function that will handle a resource creation.
func CreateResource(r rest.Creater, scope RequestScope, typer runtime.ObjectTyper, admit admission.Interface) restful.RouteFunction {
	return createHandler(&namedCreaterAdapter{r}, scope, typer, admit, false)
}

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func createHandler(r rest.NamedCreater, scope RequestScope, typer runtime.ObjectTyper, admit admission.Interface, includeName bool) restful.RouteFunction {
	return func(req *restful.Request, res *restful.Response) {
		// For performance tracking purposes.
		trace := util.NewTrace("Create " + req.Request.URL.Path)
		defer trace.LogIfLong(500 * time.Millisecond)
		w := res.ResponseWriter
		// TODO: we either want to remove timeout or document it (if we document, move timeout out of this function and declare it in api_installer)
		timeout := parseTimeout(req.Request.URL.Query().Get("timeout"))
		var (
			namespace, name string
			err             error
		)
		if includeName {
			namespace, name, err = scope.Namer.Name(req)
		} else {
			namespace, err = scope.Namer.Namespace(req)
		}
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		//***创建context，并封装入namespace变量***//
		ctx := scope.ContextFunc(req)
		ctx = api.WithNamespace(ctx, namespace)
		gv := scope.Kind.GroupVersion()
		s, err := negotiateInputSerializer(req.Request, scope.Serializer)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		decoder := scope.Serializer.DecoderToVersion(s.Serializer, unversioned.GroupVersion{Group: gv.Group, Version: runtime.APIVersionInternal})
		body, err := readBody(req.Request)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		defaultGVK := scope.Kind
		original := r.New()
		trace.Step("About to convert to expected version")
		obj, gvk, err := decoder.Decode(body, &defaultGVK, original)
		if err != nil {
			err = transformDecodeError(typer, err, original, gvk, body)
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		if gvk.GroupVersion() != gv {
			err = errors.NewBadRequest(fmt.Sprintf("the API version in the data (%s) does not match the expected API version (%v)", gvk.GroupVersion().String(), gv.String()))
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		trace.Step("Conversion done")
		if admit != nil && admit.Handles(admission.Create) {
			userInfo, _ := api.UserFrom(ctx)
			err = admit.Admit(admission.NewAttributesRecord(obj, nil, scope.Kind, namespace, name, scope.Resource, scope.Subresource, admission.Create, userInfo))
			if err != nil {
				scope.err(err, res.ResponseWriter, req.Request)
				return
			}
		}
		trace.Step("About to store object in database")
		result, err := finishRequest(timeout, func() (runtime.Object, error) {
			//***处理创建***//
			out, err := r.Create(ctx, name, obj)
			if status, ok := out.(*unversioned.Status); ok && err == nil && status.Code == 0 {
				status.Code = http.StatusCreated
			}
			return out, err
		})
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		trace.Step("Object stored in database")
		if err := setSelfLink(result, req, scope.Namer); err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		trace.Step("Self-link added")
		write(http.StatusCreated, scope.Kind.GroupVersion(), scope.Serializer, result, w, req.Request)
	}
}

DeleteResource()

DeleteResource()用来处理删除的请求。

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// DeleteResource returns a function that will handle a resource deletion
func DeleteResource(r rest.GracefulDeleter, allowsOptions bool, scope RequestScope, admit admission.Interface) restful.RouteFunction {
	return func(req *restful.Request, res *restful.Response) {
		// For performance tracking purposes.
		trace := util.NewTrace("Delete " + req.Request.URL.Path)
		defer trace.LogIfLong(500 * time.Millisecond)
		w := res.ResponseWriter
		// TODO: we either want to remove timeout or document it (if we document, move timeout out of this function and declare it in api_installer)
		timeout := parseTimeout(req.Request.URL.Query().Get("timeout"))
		namespace, name, err := scope.Namer.Name(req)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		ctx := scope.ContextFunc(req)
		ctx = api.WithNamespace(ctx, namespace)
		options := &api.DeleteOptions{}
		//***Fankang***//
		//***allowsOptions: true***//
		if allowsOptions {
			body, err := readBody(req.Request)
			if err != nil {
				scope.err(err, res.ResponseWriter, req.Request)
				return
			}
			if len(body) > 0 {
				s, err := negotiateInputSerializer(req.Request, scope.Serializer)
				if err != nil {
					scope.err(err, res.ResponseWriter, req.Request)
					return
				}
				defaultGVK := scope.Kind.GroupVersion().WithKind("DeleteOptions")
				obj, _, err := scope.Serializer.DecoderToVersion(s.Serializer, defaultGVK.GroupVersion()).Decode(body, &defaultGVK, options)
				if err != nil {
					scope.err(err, res.ResponseWriter, req.Request)
					return
				}
				if obj != options {
					scope.err(fmt.Errorf("decoded object cannot be converted to DeleteOptions"), res.ResponseWriter, req.Request)
					return
				}
			} else {
				if values := req.Request.URL.Query(); len(values) > 0 {
					if err := scope.ParameterCodec.DecodeParameters(values, scope.Kind.GroupVersion(), options); err != nil {
						scope.err(err, res.ResponseWriter, req.Request)
						return
					}
				}
			}
		}
		if admit != nil && admit.Handles(admission.Delete) {
			userInfo, _ := api.UserFrom(ctx)
			err = admit.Admit(admission.NewAttributesRecord(nil, nil, scope.Kind, namespace, name, scope.Resource, scope.Subresource, admission.Delete, userInfo))
			if err != nil {
				scope.err(err, res.ResponseWriter, req.Request)
				return
			}
		}
		trace.Step("About do delete object from database")
		result, err := finishRequest(timeout, func() (runtime.Object, error) {
			return r.Delete(ctx, name, options)
		})
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		trace.Step("Object deleted from database")
		// if the rest.Deleter returns a nil object, fill out a status. Callers may return a valid
		// object with the response.
		if result == nil {
			result = &unversioned.Status{
				Status: unversioned.StatusSuccess,
				Code:   http.StatusOK,
				Details: &unversioned.StatusDetails{
					Name: name,
					Kind: scope.Kind.Kind,
				},
			}
		} else {
			// when a non-status response is returned, set the self link
			if _, ok := result.(*unversioned.Status); !ok {
				if err := setSelfLink(result, req, scope.Namer); err != nil {
					scope.err(err, res.ResponseWriter, req.Request)
					return
				}
			}
		}
		write(http.StatusOK, scope.Kind.GroupVersion(), scope.Serializer, result, w, req.Request)
	}
}