diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/admission/interfaces.go b/metrics-server/vendor/k8s.io/apiserver/pkg/admission/interfaces.go
new file mode 100644
index 0000000..68ef558
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/admission/interfaces.go
@@ -0,0 +1,119 @@
+/*
+Copyright 2014 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package admission
+
+import (
+	"io"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apiserver/pkg/authentication/user"
+)
+
+// Attributes is an interface used by AdmissionController to get information about a request
+// that is used to make an admission decision.
+type Attributes interface {
+	// GetName returns the name of the object as presented in the request.  On a CREATE operation, the client
+	// may omit name and rely on the server to generate the name.  If that is the case, this method will return
+	// the empty string
+	GetName() string
+	// GetNamespace is the namespace associated with the request (if any)
+	GetNamespace() string
+	// GetResource is the name of the resource being requested.  This is not the kind.  For example: pods
+	GetResource() schema.GroupVersionResource
+	// GetSubresource is the name of the subresource being requested.  This is a different resource, scoped to the parent resource, but it may have a different kind.
+	// For instance, /pods has the resource "pods" and the kind "Pod", while /pods/foo/status has the resource "pods", the sub resource "status", and the kind "Pod"
+	// (because status operates on pods). The binding resource for a pod though may be /pods/foo/binding, which has resource "pods", subresource "binding", and kind "Binding".
+	GetSubresource() string
+	// GetOperation is the operation being performed
+	GetOperation() Operation
+	// GetObject is the object from the incoming request prior to default values being applied
+	GetObject() runtime.Object
+	// GetOldObject is the existing object. Only populated for UPDATE requests.
+	GetOldObject() runtime.Object
+	// GetKind is the type of object being manipulated.  For example: Pod
+	GetKind() schema.GroupVersionKind
+	// GetUserInfo is information about the requesting user
+	GetUserInfo() user.Info
+
+	// AddAnnotation sets annotation according to key-value pair. The key should be qualified, e.g., podsecuritypolicy.admission.k8s.io/admit-policy, where
+	// "podsecuritypolicy" is the name of the plugin, "admission.k8s.io" is the name of the organization, "admit-policy" is the key name.
+	// An error is returned if the format of key is invalid. When trying to overwrite annotation with a new value, an error is returned.
+	// Both ValidationInterface and MutationInterface are allowed to add Annotations.
+	AddAnnotation(key, value string) error
+}
+
+// privateAnnotationsGetter is a private interface which allows users to get annotations from Attributes.
+type privateAnnotationsGetter interface {
+	getAnnotations() map[string]string
+}
+
+// AnnotationsGetter allows users to get annotations from Attributes. An alternate Attribute should implement
+// this interface.
+type AnnotationsGetter interface {
+	GetAnnotations() map[string]string
+}
+
+// Interface is an abstract, pluggable interface for Admission Control decisions.
+type Interface interface {
+	// Handles returns true if this admission controller can handle the given operation
+	// where operation can be one of CREATE, UPDATE, DELETE, or CONNECT
+	Handles(operation Operation) bool
+}
+
+type MutationInterface interface {
+	Interface
+
+	// Admit makes an admission decision based on the request attributes
+	Admit(a Attributes) (err error)
+}
+
+// ValidationInterface is an abstract, pluggable interface for Admission Control decisions.
+type ValidationInterface interface {
+	Interface
+
+	// Validate makes an admission decision based on the request attributes.  It is NOT allowed to mutate
+	Validate(a Attributes) (err error)
+}
+
+// Operation is the type of resource operation being checked for admission control
+type Operation string
+
+// Operation constants
+const (
+	Create  Operation = "CREATE"
+	Update  Operation = "UPDATE"
+	Delete  Operation = "DELETE"
+	Connect Operation = "CONNECT"
+)
+
+// PluginInitializer is used for initialization of shareable resources between admission plugins.
+// After initialization the resources have to be set separately
+type PluginInitializer interface {
+	Initialize(plugin Interface)
+}
+
+// InitializationValidator holds ValidateInitialization functions, which are responsible for validation of initialized
+// shared resources and should be implemented on admission plugins
+type InitializationValidator interface {
+	ValidateInitialization() error
+}
+
+// ConfigProvider provides a way to get configuration for an admission plugin based on its name
+type ConfigProvider interface {
+	ConfigFor(pluginName string) (io.Reader, error)
+}