git subrepo clone (merge) https://github.com/kubernetes-incubator/metrics-server.git metrics-server

subrepo:
  subdir:   "metrics-server"
  merged:   "92d8412"
upstream:
  origin:   "https://github.com/kubernetes-incubator/metrics-server.git"
  branch:   "master"
  commit:   "92d8412"
git-subrepo:
  version:  "0.4.0"
  origin:   "???"
  commit:   "???"
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/feature/feature_gate.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/feature/feature_gate.go
new file mode 100644
index 0000000..6b051a2
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/feature/feature_gate.go
@@ -0,0 +1,347 @@
+/*
+Copyright 2016 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 feature
+
+import (
+	"fmt"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+
+	"github.com/golang/glog"
+	"github.com/spf13/pflag"
+)
+
+type Feature string
+
+const (
+	flagName = "feature-gates"
+
+	// allAlphaGate is a global toggle for alpha features. Per-feature key
+	// values override the default set by allAlphaGate. Examples:
+	//   AllAlpha=false,NewFeature=true  will result in newFeature=true
+	//   AllAlpha=true,NewFeature=false  will result in newFeature=false
+	allAlphaGate Feature = "AllAlpha"
+)
+
+var (
+	// The generic features.
+	defaultFeatures = map[Feature]FeatureSpec{
+		allAlphaGate: {Default: false, PreRelease: Alpha},
+	}
+
+	// Special handling for a few gates.
+	specialFeatures = map[Feature]func(known map[Feature]FeatureSpec, enabled map[Feature]bool, val bool){
+		allAlphaGate: setUnsetAlphaGates,
+	}
+
+	// DefaultFeatureGate is a shared global FeatureGate.
+	DefaultFeatureGate FeatureGate = NewFeatureGate()
+)
+
+type FeatureSpec struct {
+	Default    bool
+	PreRelease prerelease
+}
+
+type prerelease string
+
+const (
+	// Values for PreRelease.
+	Alpha = prerelease("ALPHA")
+	Beta  = prerelease("BETA")
+	GA    = prerelease("")
+
+	// Deprecated
+	Deprecated = prerelease("DEPRECATED")
+)
+
+// FeatureGate parses and stores flag gates for known features from
+// a string like feature1=true,feature2=false,...
+type FeatureGate interface {
+	// AddFlag adds a flag for setting global feature gates to the specified FlagSet.
+	AddFlag(fs *pflag.FlagSet)
+	// Set parses and stores flag gates for known features
+	// from a string like feature1=true,feature2=false,...
+	Set(value string) error
+	// SetFromMap stores flag gates for known features from a map[string]bool or returns an error
+	SetFromMap(m map[string]bool) error
+	// Enabled returns true if the key is enabled.
+	Enabled(key Feature) bool
+	// Add adds features to the featureGate.
+	Add(features map[Feature]FeatureSpec) error
+	// KnownFeatures returns a slice of strings describing the FeatureGate's known features.
+	KnownFeatures() []string
+	// DeepCopy returns a deep copy of the FeatureGate object, such that gates can be
+	// set on the copy without mutating the original. This is useful for validating
+	// config against potential feature gate changes before committing those changes.
+	DeepCopy() FeatureGate
+}
+
+// featureGate implements FeatureGate as well as pflag.Value for flag parsing.
+type featureGate struct {
+	special map[Feature]func(map[Feature]FeatureSpec, map[Feature]bool, bool)
+
+	// lock guards writes to known, enabled, and reads/writes of closed
+	lock sync.Mutex
+	// known holds a map[Feature]FeatureSpec
+	known *atomic.Value
+	// enabled holds a map[Feature]bool
+	enabled *atomic.Value
+	// closed is set to true when AddFlag is called, and prevents subsequent calls to Add
+	closed bool
+}
+
+func setUnsetAlphaGates(known map[Feature]FeatureSpec, enabled map[Feature]bool, val bool) {
+	for k, v := range known {
+		if v.PreRelease == Alpha {
+			if _, found := enabled[k]; !found {
+				enabled[k] = val
+			}
+		}
+	}
+}
+
+// Set, String, and Type implement pflag.Value
+var _ pflag.Value = &featureGate{}
+
+func NewFeatureGate() *featureGate {
+	known := map[Feature]FeatureSpec{}
+	for k, v := range defaultFeatures {
+		known[k] = v
+	}
+
+	knownValue := &atomic.Value{}
+	knownValue.Store(known)
+
+	enabled := map[Feature]bool{}
+	enabledValue := &atomic.Value{}
+	enabledValue.Store(enabled)
+
+	f := &featureGate{
+		known:   knownValue,
+		special: specialFeatures,
+		enabled: enabledValue,
+	}
+	return f
+}
+
+// Set parses a string of the form "key1=value1,key2=value2,..." into a
+// map[string]bool of known keys or returns an error.
+func (f *featureGate) Set(value string) error {
+	f.lock.Lock()
+	defer f.lock.Unlock()
+
+	// Copy existing state
+	known := map[Feature]FeatureSpec{}
+	for k, v := range f.known.Load().(map[Feature]FeatureSpec) {
+		known[k] = v
+	}
+	enabled := map[Feature]bool{}
+	for k, v := range f.enabled.Load().(map[Feature]bool) {
+		enabled[k] = v
+	}
+
+	for _, s := range strings.Split(value, ",") {
+		if len(s) == 0 {
+			continue
+		}
+		arr := strings.SplitN(s, "=", 2)
+		k := Feature(strings.TrimSpace(arr[0]))
+		featureSpec, ok := known[k]
+		if !ok {
+			return fmt.Errorf("unrecognized key: %s", k)
+		}
+		if len(arr) != 2 {
+			return fmt.Errorf("missing bool value for %s", k)
+		}
+		v := strings.TrimSpace(arr[1])
+		boolValue, err := strconv.ParseBool(v)
+		if err != nil {
+			return fmt.Errorf("invalid value of %s: %s, err: %v", k, v, err)
+		}
+		enabled[k] = boolValue
+		if boolValue && featureSpec.PreRelease == Deprecated {
+			glog.Warningf("enabling deprecated feature gate %s", k)
+		}
+
+		// Handle "special" features like "all alpha gates"
+		if fn, found := f.special[k]; found {
+			fn(known, enabled, boolValue)
+		}
+	}
+
+	// Persist changes
+	f.known.Store(known)
+	f.enabled.Store(enabled)
+
+	glog.V(1).Infof("feature gates: %v", enabled)
+	return nil
+}
+
+// SetFromMap stores flag gates for known features from a map[string]bool or returns an error
+func (f *featureGate) SetFromMap(m map[string]bool) error {
+	f.lock.Lock()
+	defer f.lock.Unlock()
+
+	// Copy existing state
+	known := map[Feature]FeatureSpec{}
+	for k, v := range f.known.Load().(map[Feature]FeatureSpec) {
+		known[k] = v
+	}
+	enabled := map[Feature]bool{}
+	for k, v := range f.enabled.Load().(map[Feature]bool) {
+		enabled[k] = v
+	}
+
+	for k, v := range m {
+		k := Feature(k)
+		_, ok := known[k]
+		if !ok {
+			return fmt.Errorf("unrecognized key: %s", k)
+		}
+		enabled[k] = v
+		// Handle "special" features like "all alpha gates"
+		if fn, found := f.special[k]; found {
+			fn(known, enabled, v)
+		}
+	}
+
+	// Persist changes
+	f.known.Store(known)
+	f.enabled.Store(enabled)
+
+	glog.V(1).Infof("feature gates: %v", f.enabled)
+	return nil
+}
+
+// String returns a string containing all enabled feature gates, formatted as "key1=value1,key2=value2,...".
+func (f *featureGate) String() string {
+	pairs := []string{}
+	for k, v := range f.enabled.Load().(map[Feature]bool) {
+		pairs = append(pairs, fmt.Sprintf("%s=%t", k, v))
+	}
+	sort.Strings(pairs)
+	return strings.Join(pairs, ",")
+}
+
+func (f *featureGate) Type() string {
+	return "mapStringBool"
+}
+
+// Add adds features to the featureGate.
+func (f *featureGate) Add(features map[Feature]FeatureSpec) error {
+	f.lock.Lock()
+	defer f.lock.Unlock()
+
+	if f.closed {
+		return fmt.Errorf("cannot add a feature gate after adding it to the flag set")
+	}
+
+	// Copy existing state
+	known := map[Feature]FeatureSpec{}
+	for k, v := range f.known.Load().(map[Feature]FeatureSpec) {
+		known[k] = v
+	}
+
+	for name, spec := range features {
+		if existingSpec, found := known[name]; found {
+			if existingSpec == spec {
+				continue
+			}
+			return fmt.Errorf("feature gate %q with different spec already exists: %v", name, existingSpec)
+		}
+
+		known[name] = spec
+	}
+
+	// Persist updated state
+	f.known.Store(known)
+
+	return nil
+}
+
+// Enabled returns true if the key is enabled.
+func (f *featureGate) Enabled(key Feature) bool {
+	if v, ok := f.enabled.Load().(map[Feature]bool)[key]; ok {
+		return v
+	}
+	return f.known.Load().(map[Feature]FeatureSpec)[key].Default
+}
+
+// AddFlag adds a flag for setting global feature gates to the specified FlagSet.
+func (f *featureGate) AddFlag(fs *pflag.FlagSet) {
+	f.lock.Lock()
+	// TODO(mtaufen): Shouldn't we just close it on the first Set/SetFromMap instead?
+	// Not all components expose a feature gates flag using this AddFlag method, and
+	// in the future, all components will completely stop exposing a feature gates flag,
+	// in favor of componentconfig.
+	f.closed = true
+	f.lock.Unlock()
+
+	known := f.KnownFeatures()
+	fs.Var(f, flagName, ""+
+		"A set of key=value pairs that describe feature gates for alpha/experimental features. "+
+		"Options are:\n"+strings.Join(known, "\n"))
+}
+
+// KnownFeatures returns a slice of strings describing the FeatureGate's known features.
+func (f *featureGate) KnownFeatures() []string {
+	var known []string
+	for k, v := range f.known.Load().(map[Feature]FeatureSpec) {
+		pre := ""
+		if v.PreRelease != GA {
+			pre = fmt.Sprintf("%s - ", v.PreRelease)
+		}
+		known = append(known, fmt.Sprintf("%s=true|false (%sdefault=%t)", k, pre, v.Default))
+	}
+	sort.Strings(known)
+	return known
+}
+
+// DeepCopy returns a deep copy of the FeatureGate object, such that gates can be
+// set on the copy without mutating the original. This is useful for validating
+// config against potential feature gate changes before committing those changes.
+func (f *featureGate) DeepCopy() FeatureGate {
+	// Copy existing state.
+	known := map[Feature]FeatureSpec{}
+	for k, v := range f.known.Load().(map[Feature]FeatureSpec) {
+		known[k] = v
+	}
+	enabled := map[Feature]bool{}
+	for k, v := range f.enabled.Load().(map[Feature]bool) {
+		enabled[k] = v
+	}
+
+	// Store copied state in new atomics.
+	knownValue := &atomic.Value{}
+	knownValue.Store(known)
+	enabledValue := &atomic.Value{}
+	enabledValue.Store(enabled)
+
+	// Construct a new featureGate around the copied state.
+	// Note that specialFeatures is treated as immutable by convention,
+	// and we maintain the value of f.closed across the copy.
+	return &featureGate{
+		special: specialFeatures,
+		known:   knownValue,
+		enabled: enabledValue,
+		closed:  f.closed,
+	}
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/ciphersuites_flag.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/ciphersuites_flag.go
new file mode 100644
index 0000000..764747c
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/ciphersuites_flag.go
@@ -0,0 +1,105 @@
+/*
+Copyright 2017 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 flag
+
+import (
+	"crypto/tls"
+	"fmt"
+
+	"k8s.io/apimachinery/pkg/util/sets"
+)
+
+// ciphers maps strings into tls package cipher constants in
+// https://golang.org/pkg/crypto/tls/#pkg-constants
+var ciphers = map[string]uint16{
+	"TLS_RSA_WITH_RC4_128_SHA":                tls.TLS_RSA_WITH_RC4_128_SHA,
+	"TLS_RSA_WITH_3DES_EDE_CBC_SHA":           tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA,
+	"TLS_RSA_WITH_AES_128_CBC_SHA":            tls.TLS_RSA_WITH_AES_128_CBC_SHA,
+	"TLS_RSA_WITH_AES_256_CBC_SHA":            tls.TLS_RSA_WITH_AES_256_CBC_SHA,
+	"TLS_RSA_WITH_AES_128_CBC_SHA256":         tls.TLS_RSA_WITH_AES_128_CBC_SHA256,
+	"TLS_RSA_WITH_AES_128_GCM_SHA256":         tls.TLS_RSA_WITH_AES_128_GCM_SHA256,
+	"TLS_RSA_WITH_AES_256_GCM_SHA384":         tls.TLS_RSA_WITH_AES_256_GCM_SHA384,
+	"TLS_ECDHE_ECDSA_WITH_RC4_128_SHA":        tls.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA,
+	"TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA":    tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
+	"TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA":    tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
+	"TLS_ECDHE_RSA_WITH_RC4_128_SHA":          tls.TLS_ECDHE_RSA_WITH_RC4_128_SHA,
+	"TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA":     tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
+	"TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA":      tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
+	"TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA":      tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
+	"TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256": tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256,
+	"TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256":   tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256,
+	"TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256":   tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
+	"TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256": tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
+	"TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384":   tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
+	"TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384": tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
+	"TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305":    tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
+	"TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305":  tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
+}
+
+func TLSCipherPossibleValues() []string {
+	cipherKeys := sets.NewString()
+	for key := range ciphers {
+		cipherKeys.Insert(key)
+	}
+	return cipherKeys.List()
+}
+
+func TLSCipherSuites(cipherNames []string) ([]uint16, error) {
+	if len(cipherNames) == 0 {
+		return nil, nil
+	}
+	ciphersIntSlice := make([]uint16, 0)
+	for _, cipher := range cipherNames {
+		intValue, ok := ciphers[cipher]
+		if !ok {
+			return nil, fmt.Errorf("Cipher suite %s not supported or doesn't exist", cipher)
+		}
+		ciphersIntSlice = append(ciphersIntSlice, intValue)
+	}
+	return ciphersIntSlice, nil
+}
+
+var versions = map[string]uint16{
+	"VersionTLS10": tls.VersionTLS10,
+	"VersionTLS11": tls.VersionTLS11,
+	"VersionTLS12": tls.VersionTLS12,
+}
+
+func TLSPossibleVersions() []string {
+	versionsKeys := sets.NewString()
+	for key := range versions {
+		versionsKeys.Insert(key)
+	}
+	return versionsKeys.List()
+}
+
+func TLSVersion(versionName string) (uint16, error) {
+	if len(versionName) == 0 {
+		return DefaultTLSVersion(), nil
+	}
+	if version, ok := versions[versionName]; ok {
+		return version, nil
+	}
+	return 0, fmt.Errorf("unknown tls version %q", versionName)
+}
+
+func DefaultTLSVersion() uint16 {
+	// Can't use SSLv3 because of POODLE and BEAST
+	// Can't use TLSv1.0 because of POODLE and BEAST using CBC cipher
+	// Can't use TLSv1.1 because of RC4 cipher usage
+	return tls.VersionTLS12
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/colon_separated_multimap_string_string.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/colon_separated_multimap_string_string.go
new file mode 100644
index 0000000..bd2cf5f
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/colon_separated_multimap_string_string.go
@@ -0,0 +1,102 @@
+/*
+Copyright 2017 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 flag
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// ColonSeparatedMultimapStringString supports setting a map[string][]string from an encoding
+// that separates keys from values with ':' and separates key-value pairs with ','.
+// A key can be repeated multiple times, in which case the values are appended to a
+// slice of strings associated with that key. Items in the list associated with a given
+// key will appear in the order provided.
+// For example: `a:hello,b:again,c:world,b:beautiful` results in `{"a": ["hello"], "b": ["again", "beautiful"], "c": ["world"]}`
+// The first call to Set will clear the map before adding entries; subsequent calls will simply append to the map.
+// This makes it possible to override default values with a command-line option rather than appending to defaults,
+// while still allowing the distribution of key-value pairs across multiple flag invocations.
+// For example: `--flag "a:hello" --flag "b:again" --flag "b:beautiful" --flag "c:world"` results in `{"a": ["hello"], "b": ["again", "beautiful"], "c": ["world"]}`
+type ColonSeparatedMultimapStringString struct {
+	Multimap    *map[string][]string
+	initialized bool // set to true after the first Set call
+}
+
+// NewColonSeparatedMultimapStringString takes a pointer to a map[string][]string and returns the
+// ColonSeparatedMultimapStringString flag parsing shim for that map.
+func NewColonSeparatedMultimapStringString(m *map[string][]string) *ColonSeparatedMultimapStringString {
+	return &ColonSeparatedMultimapStringString{Multimap: m}
+}
+
+// Set implements github.com/spf13/pflag.Value
+func (m *ColonSeparatedMultimapStringString) Set(value string) error {
+	if m.Multimap == nil {
+		return fmt.Errorf("no target (nil pointer to map[string][]string)")
+	}
+	if !m.initialized || *m.Multimap == nil {
+		// clear default values, or allocate if no existing map
+		*m.Multimap = make(map[string][]string)
+		m.initialized = true
+	}
+	for _, pair := range strings.Split(value, ",") {
+		if len(pair) == 0 {
+			continue
+		}
+		kv := strings.SplitN(pair, ":", 2)
+		if len(kv) != 2 {
+			return fmt.Errorf("malformed pair, expect string:string")
+		}
+		k := strings.TrimSpace(kv[0])
+		v := strings.TrimSpace(kv[1])
+		(*m.Multimap)[k] = append((*m.Multimap)[k], v)
+	}
+	return nil
+}
+
+// String implements github.com/spf13/pflag.Value
+func (m *ColonSeparatedMultimapStringString) String() string {
+	type kv struct {
+		k string
+		v string
+	}
+	kvs := make([]kv, 0, len(*m.Multimap))
+	for k, vs := range *m.Multimap {
+		for i := range vs {
+			kvs = append(kvs, kv{k: k, v: vs[i]})
+		}
+	}
+	// stable sort by keys, order of values should be preserved
+	sort.SliceStable(kvs, func(i, j int) bool {
+		return kvs[i].k < kvs[j].k
+	})
+	pairs := make([]string, 0, len(kvs))
+	for i := range kvs {
+		pairs = append(pairs, fmt.Sprintf("%s:%s", kvs[i].k, kvs[i].v))
+	}
+	return strings.Join(pairs, ",")
+}
+
+// Type implements github.com/spf13/pflag.Value
+func (m *ColonSeparatedMultimapStringString) Type() string {
+	return "colonSeparatedMultimapStringString"
+}
+
+// Empty implements OmitEmpty
+func (m *ColonSeparatedMultimapStringString) Empty() bool {
+	return len(*m.Multimap) == 0
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/configuration_map.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/configuration_map.go
new file mode 100644
index 0000000..911b05e
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/configuration_map.go
@@ -0,0 +1,53 @@
+/*
+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 flag
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+type ConfigurationMap map[string]string
+
+func (m *ConfigurationMap) String() string {
+	pairs := []string{}
+	for k, v := range *m {
+		pairs = append(pairs, fmt.Sprintf("%s=%s", k, v))
+	}
+	sort.Strings(pairs)
+	return strings.Join(pairs, ",")
+}
+
+func (m *ConfigurationMap) Set(value string) error {
+	for _, s := range strings.Split(value, ",") {
+		if len(s) == 0 {
+			continue
+		}
+		arr := strings.SplitN(s, "=", 2)
+		if len(arr) == 2 {
+			(*m)[strings.TrimSpace(arr[0])] = strings.TrimSpace(arr[1])
+		} else {
+			(*m)[strings.TrimSpace(arr[0])] = ""
+		}
+	}
+	return nil
+}
+
+func (*ConfigurationMap) Type() string {
+	return "mapStringString"
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/flags.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/flags.go
new file mode 100644
index 0000000..55a3ed3
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/flags.go
@@ -0,0 +1,54 @@
+/*
+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 flag
+
+import (
+	goflag "flag"
+	"strings"
+
+	"github.com/golang/glog"
+	"github.com/spf13/pflag"
+)
+
+// WordSepNormalizeFunc changes all flags that contain "_" separators
+func WordSepNormalizeFunc(f *pflag.FlagSet, name string) pflag.NormalizedName {
+	if strings.Contains(name, "_") {
+		return pflag.NormalizedName(strings.Replace(name, "_", "-", -1))
+	}
+	return pflag.NormalizedName(name)
+}
+
+// WarnWordSepNormalizeFunc changes and warns for flags that contain "_" separators
+func WarnWordSepNormalizeFunc(f *pflag.FlagSet, name string) pflag.NormalizedName {
+	if strings.Contains(name, "_") {
+		nname := strings.Replace(name, "_", "-", -1)
+		glog.Warningf("%s is DEPRECATED and will be removed in a future version. Use %s instead.", name, nname)
+
+		return pflag.NormalizedName(nname)
+	}
+	return pflag.NormalizedName(name)
+}
+
+// InitFlags normalizes, parses, then logs the command line flags
+func InitFlags() {
+	pflag.CommandLine.SetNormalizeFunc(WordSepNormalizeFunc)
+	pflag.CommandLine.AddGoFlagSet(goflag.CommandLine)
+	pflag.Parse()
+	pflag.VisitAll(func(flag *pflag.Flag) {
+		glog.V(2).Infof("FLAG: --%s=%q", flag.Name, flag.Value)
+	})
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/langle_separated_map_string_string.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/langle_separated_map_string_string.go
new file mode 100644
index 0000000..bf8dbfb
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/langle_separated_map_string_string.go
@@ -0,0 +1,82 @@
+/*
+Copyright 2017 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 flag
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// LangleSeparatedMapStringString can be set from the command line with the format `--flag "string<string"`.
+// Multiple comma-separated key-value pairs in a single invocation are supported. For example: `--flag "a<foo,b<bar"`.
+// Multiple flag invocations are supported. For example: `--flag "a<foo" --flag "b<foo"`.
+type LangleSeparatedMapStringString struct {
+	Map         *map[string]string
+	initialized bool // set to true after first Set call
+}
+
+// NewLangleSeparatedMapStringString takes a pointer to a map[string]string and returns the
+// LangleSeparatedMapStringString flag parsing shim for that map
+func NewLangleSeparatedMapStringString(m *map[string]string) *LangleSeparatedMapStringString {
+	return &LangleSeparatedMapStringString{Map: m}
+}
+
+// String implements github.com/spf13/pflag.Value
+func (m *LangleSeparatedMapStringString) String() string {
+	pairs := []string{}
+	for k, v := range *m.Map {
+		pairs = append(pairs, fmt.Sprintf("%s<%s", k, v))
+	}
+	sort.Strings(pairs)
+	return strings.Join(pairs, ",")
+}
+
+// Set implements github.com/spf13/pflag.Value
+func (m *LangleSeparatedMapStringString) Set(value string) error {
+	if m.Map == nil {
+		return fmt.Errorf("no target (nil pointer to map[string]string)")
+	}
+	if !m.initialized || *m.Map == nil {
+		// clear default values, or allocate if no existing map
+		*m.Map = make(map[string]string)
+		m.initialized = true
+	}
+	for _, s := range strings.Split(value, ",") {
+		if len(s) == 0 {
+			continue
+		}
+		arr := strings.SplitN(s, "<", 2)
+		if len(arr) != 2 {
+			return fmt.Errorf("malformed pair, expect string<string")
+		}
+		k := strings.TrimSpace(arr[0])
+		v := strings.TrimSpace(arr[1])
+		(*m.Map)[k] = v
+	}
+	return nil
+}
+
+// Type implements github.com/spf13/pflag.Value
+func (*LangleSeparatedMapStringString) Type() string {
+	return "mapStringString"
+}
+
+// Empty implements OmitEmpty
+func (m *LangleSeparatedMapStringString) Empty() bool {
+	return len(*m.Map) == 0
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/map_string_bool.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/map_string_bool.go
new file mode 100644
index 0000000..e5a0180
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/map_string_bool.go
@@ -0,0 +1,90 @@
+/*
+Copyright 2017 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 flag
+
+import (
+	"fmt"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+// MapStringBool can be set from the command line with the format `--flag "string=bool"`.
+// Multiple comma-separated key-value pairs in a single invocation are supported. For example: `--flag "a=true,b=false"`.
+// Multiple flag invocations are supported. For example: `--flag "a=true" --flag "b=false"`.
+type MapStringBool struct {
+	Map         *map[string]bool
+	initialized bool
+}
+
+// NewMapStringBool takes a pointer to a map[string]string and returns the
+// MapStringBool flag parsing shim for that map
+func NewMapStringBool(m *map[string]bool) *MapStringBool {
+	return &MapStringBool{Map: m}
+}
+
+// String implements github.com/spf13/pflag.Value
+func (m *MapStringBool) String() string {
+	if m == nil || m.Map == nil {
+		return ""
+	}
+	pairs := []string{}
+	for k, v := range *m.Map {
+		pairs = append(pairs, fmt.Sprintf("%s=%t", k, v))
+	}
+	sort.Strings(pairs)
+	return strings.Join(pairs, ",")
+}
+
+// Set implements github.com/spf13/pflag.Value
+func (m *MapStringBool) Set(value string) error {
+	if m.Map == nil {
+		return fmt.Errorf("no target (nil pointer to map[string]bool)")
+	}
+	if !m.initialized || *m.Map == nil {
+		// clear default values, or allocate if no existing map
+		*m.Map = make(map[string]bool)
+		m.initialized = true
+	}
+	for _, s := range strings.Split(value, ",") {
+		if len(s) == 0 {
+			continue
+		}
+		arr := strings.SplitN(s, "=", 2)
+		if len(arr) != 2 {
+			return fmt.Errorf("malformed pair, expect string=bool")
+		}
+		k := strings.TrimSpace(arr[0])
+		v := strings.TrimSpace(arr[1])
+		boolValue, err := strconv.ParseBool(v)
+		if err != nil {
+			return fmt.Errorf("invalid value of %s: %s, err: %v", k, v, err)
+		}
+		(*m.Map)[k] = boolValue
+	}
+	return nil
+}
+
+// Type implements github.com/spf13/pflag.Value
+func (*MapStringBool) Type() string {
+	return "mapStringBool"
+}
+
+// Empty implements OmitEmpty
+func (m *MapStringBool) Empty() bool {
+	return len(*m.Map) == 0
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/map_string_string.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/map_string_string.go
new file mode 100644
index 0000000..129470b
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/map_string_string.go
@@ -0,0 +1,112 @@
+/*
+Copyright 2017 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 flag
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// MapStringString can be set from the command line with the format `--flag "string=string"`.
+// Multiple flag invocations are supported. For example: `--flag "a=foo" --flag "b=bar"`. If this is desired
+// to be the only type invocation `NoSplit` should be set to true.
+// Multiple comma-separated key-value pairs in a single invocation are supported if `NoSplit`
+// is set to false. For example: `--flag "a=foo,b=bar"`.
+type MapStringString struct {
+	Map         *map[string]string
+	initialized bool
+	NoSplit     bool
+}
+
+// NewMapStringString takes a pointer to a map[string]string and returns the
+// MapStringString flag parsing shim for that map
+func NewMapStringString(m *map[string]string) *MapStringString {
+	return &MapStringString{Map: m}
+}
+
+// NewMapStringString takes a pointer to a map[string]string and sets `NoSplit`
+// value to `true` and returns the MapStringString flag parsing shim for that map
+func NewMapStringStringNoSplit(m *map[string]string) *MapStringString {
+	return &MapStringString{
+		Map:     m,
+		NoSplit: true,
+	}
+}
+
+// String implements github.com/spf13/pflag.Value
+func (m *MapStringString) String() string {
+	if m == nil || m.Map == nil {
+		return ""
+	}
+	pairs := []string{}
+	for k, v := range *m.Map {
+		pairs = append(pairs, fmt.Sprintf("%s=%s", k, v))
+	}
+	sort.Strings(pairs)
+	return strings.Join(pairs, ",")
+}
+
+// Set implements github.com/spf13/pflag.Value
+func (m *MapStringString) Set(value string) error {
+	if m.Map == nil {
+		return fmt.Errorf("no target (nil pointer to map[string]string)")
+	}
+	if !m.initialized || *m.Map == nil {
+		// clear default values, or allocate if no existing map
+		*m.Map = make(map[string]string)
+		m.initialized = true
+	}
+
+	// account for comma-separated key-value pairs in a single invocation
+	if !m.NoSplit {
+		for _, s := range strings.Split(value, ",") {
+			if len(s) == 0 {
+				continue
+			}
+			arr := strings.SplitN(s, "=", 2)
+			if len(arr) != 2 {
+				return fmt.Errorf("malformed pair, expect string=string")
+			}
+			k := strings.TrimSpace(arr[0])
+			v := strings.TrimSpace(arr[1])
+			(*m.Map)[k] = v
+		}
+		return nil
+	}
+
+	// account for only one key-value pair in a single invocation
+	arr := strings.SplitN(value, "=", 2)
+	if len(arr) != 2 {
+		return fmt.Errorf("malformed pair, expect string=string")
+	}
+	k := strings.TrimSpace(arr[0])
+	v := strings.TrimSpace(arr[1])
+	(*m.Map)[k] = v
+	return nil
+
+}
+
+// Type implements github.com/spf13/pflag.Value
+func (*MapStringString) Type() string {
+	return "mapStringString"
+}
+
+// Empty implements OmitEmpty
+func (m *MapStringString) Empty() bool {
+	return len(*m.Map) == 0
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/namedcertkey_flag.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/namedcertkey_flag.go
new file mode 100644
index 0000000..bc68677
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/namedcertkey_flag.go
@@ -0,0 +1,113 @@
+/*
+Copyright 2016 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 flag
+
+import (
+	"errors"
+	"flag"
+	"strings"
+)
+
+// NamedCertKey is a flag value parsing "certfile,keyfile" and "certfile,keyfile:name,name,name".
+type NamedCertKey struct {
+	Names             []string
+	CertFile, KeyFile string
+}
+
+var _ flag.Value = &NamedCertKey{}
+
+func (nkc *NamedCertKey) String() string {
+	s := nkc.CertFile + "," + nkc.KeyFile
+	if len(nkc.Names) > 0 {
+		s = s + ":" + strings.Join(nkc.Names, ",")
+	}
+	return s
+}
+
+func (nkc *NamedCertKey) Set(value string) error {
+	cs := strings.SplitN(value, ":", 2)
+	var keycert string
+	if len(cs) == 2 {
+		var names string
+		keycert, names = strings.TrimSpace(cs[0]), strings.TrimSpace(cs[1])
+		if names == "" {
+			return errors.New("empty names list is not allowed")
+		}
+		nkc.Names = nil
+		for _, name := range strings.Split(names, ",") {
+			nkc.Names = append(nkc.Names, strings.TrimSpace(name))
+		}
+	} else {
+		nkc.Names = nil
+		keycert = strings.TrimSpace(cs[0])
+	}
+	cs = strings.Split(keycert, ",")
+	if len(cs) != 2 {
+		return errors.New("expected comma separated certificate and key file paths")
+	}
+	nkc.CertFile = strings.TrimSpace(cs[0])
+	nkc.KeyFile = strings.TrimSpace(cs[1])
+	return nil
+}
+
+func (*NamedCertKey) Type() string {
+	return "namedCertKey"
+}
+
+// NamedCertKeyArray is a flag value parsing NamedCertKeys, each passed with its own
+// flag instance (in contrast to comma separated slices).
+type NamedCertKeyArray struct {
+	value   *[]NamedCertKey
+	changed bool
+}
+
+var _ flag.Value = &NamedCertKey{}
+
+// NewNamedKeyCertArray creates a new NamedCertKeyArray with the internal value
+// pointing to p.
+func NewNamedCertKeyArray(p *[]NamedCertKey) *NamedCertKeyArray {
+	return &NamedCertKeyArray{
+		value: p,
+	}
+}
+
+func (a *NamedCertKeyArray) Set(val string) error {
+	nkc := NamedCertKey{}
+	err := nkc.Set(val)
+	if err != nil {
+		return err
+	}
+	if !a.changed {
+		*a.value = []NamedCertKey{nkc}
+		a.changed = true
+	} else {
+		*a.value = append(*a.value, nkc)
+	}
+	return nil
+}
+
+func (a *NamedCertKeyArray) Type() string {
+	return "namedCertKey"
+}
+
+func (a *NamedCertKeyArray) String() string {
+	nkcs := make([]string, 0, len(*a.value))
+	for i := range *a.value {
+		nkcs = append(nkcs, (*a.value)[i].String())
+	}
+	return "[" + strings.Join(nkcs, ";") + "]"
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/noop.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/noop.go
new file mode 100644
index 0000000..03f7f14
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/noop.go
@@ -0,0 +1,41 @@
+/*
+Copyright 2018 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 flag
+
+import (
+	goflag "flag"
+	"github.com/spf13/pflag"
+)
+
+// NoOp implements goflag.Value and plfag.Value,
+// but has a noop Set implementation
+type NoOp struct{}
+
+var _ goflag.Value = NoOp{}
+var _ pflag.Value = NoOp{}
+
+func (NoOp) String() string {
+	return ""
+}
+
+func (NoOp) Set(val string) error {
+	return nil
+}
+
+func (NoOp) Type() string {
+	return "NoOp"
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/omitempty.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/omitempty.go
new file mode 100644
index 0000000..c354754
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/omitempty.go
@@ -0,0 +1,24 @@
+/*
+Copyright 2017 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 flag
+
+// OmitEmpty is an interface for flags to report whether their underlying value
+// is "empty." If a flag implements OmitEmpty and returns true for a call to Empty(),
+// it is assumed that flag may be omitted from the command line.
+type OmitEmpty interface {
+	Empty() bool
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/string_flag.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/string_flag.go
new file mode 100644
index 0000000..331bdb6
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/string_flag.go
@@ -0,0 +1,56 @@
+/*
+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 flag
+
+// StringFlag is a string flag compatible with flags and pflags that keeps track of whether it had a value supplied or not.
+type StringFlag struct {
+	// If Set has been invoked this value is true
+	provided bool
+	// The exact value provided on the flag
+	value string
+}
+
+func NewStringFlag(defaultVal string) StringFlag {
+	return StringFlag{value: defaultVal}
+}
+
+func (f *StringFlag) Default(value string) {
+	f.value = value
+}
+
+func (f StringFlag) String() string {
+	return f.value
+}
+
+func (f StringFlag) Value() string {
+	return f.value
+}
+
+func (f *StringFlag) Set(value string) error {
+	f.value = value
+	f.provided = true
+
+	return nil
+}
+
+func (f StringFlag) Provided() bool {
+	return f.provided
+}
+
+func (f *StringFlag) Type() string {
+	return "string"
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/tristate.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/tristate.go
new file mode 100644
index 0000000..cf16376
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flag/tristate.go
@@ -0,0 +1,83 @@
+/*
+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 flag
+
+import (
+	"fmt"
+	"strconv"
+)
+
+// Tristate is a flag compatible with flags and pflags that
+// keeps track of whether it had a value supplied or not.
+type Tristate int
+
+const (
+	Unset Tristate = iota // 0
+	True
+	False
+)
+
+func (f *Tristate) Default(value bool) {
+	*f = triFromBool(value)
+}
+
+func (f Tristate) String() string {
+	b := boolFromTri(f)
+	return fmt.Sprintf("%t", b)
+}
+
+func (f Tristate) Value() bool {
+	b := boolFromTri(f)
+	return b
+}
+
+func (f *Tristate) Set(value string) error {
+	boolVal, err := strconv.ParseBool(value)
+	if err != nil {
+		return err
+	}
+
+	*f = triFromBool(boolVal)
+	return nil
+}
+
+func (f Tristate) Provided() bool {
+	if f != Unset {
+		return true
+	}
+	return false
+}
+
+func (f *Tristate) Type() string {
+	return "tristate"
+}
+
+func boolFromTri(t Tristate) bool {
+	if t == True {
+		return true
+	} else {
+		return false
+	}
+}
+
+func triFromBool(b bool) Tristate {
+	if b {
+		return True
+	} else {
+		return False
+	}
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flushwriter/doc.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flushwriter/doc.go
new file mode 100644
index 0000000..f81e09a
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flushwriter/doc.go
@@ -0,0 +1,19 @@
+/*
+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 flushwriter implements a wrapper for a writer that flushes on every
+// write if that writer implements the io.Flusher interface
+package flushwriter // import "k8s.io/apiserver/pkg/util/flushwriter"
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/flushwriter/writer.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flushwriter/writer.go
new file mode 100644
index 0000000..748bd01
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/flushwriter/writer.go
@@ -0,0 +1,53 @@
+/*
+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 flushwriter
+
+import (
+	"io"
+	"net/http"
+)
+
+// Wrap wraps an io.Writer into a writer that flushes after every write if
+// the writer implements the Flusher interface.
+func Wrap(w io.Writer) io.Writer {
+	fw := &flushWriter{
+		writer: w,
+	}
+	if flusher, ok := w.(http.Flusher); ok {
+		fw.flusher = flusher
+	}
+	return fw
+}
+
+// flushWriter provides wrapper for responseWriter with HTTP streaming capabilities
+type flushWriter struct {
+	flusher http.Flusher
+	writer  io.Writer
+}
+
+// Write is a FlushWriter implementation of the io.Writer that sends any buffered
+// data to the client.
+func (fw *flushWriter) Write(p []byte) (n int, err error) {
+	n, err = fw.writer.Write(p)
+	if err != nil {
+		return
+	}
+	if fw.flusher != nil {
+		fw.flusher.Flush()
+	}
+	return
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/logs/logs.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/logs/logs.go
new file mode 100644
index 0000000..c5ba084
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/logs/logs.go
@@ -0,0 +1,69 @@
+/*
+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 logs
+
+import (
+	"flag"
+	"log"
+	"time"
+
+	"github.com/golang/glog"
+	"github.com/spf13/pflag"
+	"k8s.io/apimachinery/pkg/util/wait"
+)
+
+const logFlushFreqFlagName = "log-flush-frequency"
+
+var logFlushFreq = pflag.Duration(logFlushFreqFlagName, 5*time.Second, "Maximum number of seconds between log flushes")
+
+// TODO(thockin): This is temporary until we agree on log dirs and put those into each cmd.
+func init() {
+	flag.Set("logtostderr", "true")
+}
+
+// AddFlags registers this package's flags on arbitrary FlagSets, such that they point to the
+// same value as the global flags.
+func AddFlags(fs *pflag.FlagSet) {
+	fs.AddFlag(pflag.Lookup(logFlushFreqFlagName))
+}
+
+// GlogWriter serves as a bridge between the standard log package and the glog package.
+type GlogWriter struct{}
+
+// Write implements the io.Writer interface.
+func (writer GlogWriter) Write(data []byte) (n int, err error) {
+	glog.Info(string(data))
+	return len(data), nil
+}
+
+// InitLogs initializes logs the way we want for kubernetes.
+func InitLogs() {
+	log.SetOutput(GlogWriter{})
+	log.SetFlags(0)
+	// The default glog flush interval is 5 seconds.
+	go wait.Forever(glog.Flush, *logFlushFreq)
+}
+
+// FlushLogs flushes logs immediately.
+func FlushLogs() {
+	glog.Flush()
+}
+
+// NewLogger creates a new log.Logger which sends logs to glog.Info.
+func NewLogger(prefix string) *log.Logger {
+	return log.New(GlogWriter{}, prefix, 0)
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/openapi/proto.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/openapi/proto.go
new file mode 100644
index 0000000..5641d1a
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/openapi/proto.go
@@ -0,0 +1,142 @@
+/*
+Copyright 2018 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 openapi
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/go-openapi/spec"
+	openapi_v2 "github.com/googleapis/gnostic/OpenAPIv2"
+	"github.com/googleapis/gnostic/compiler"
+	yaml "gopkg.in/yaml.v2"
+
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/kube-openapi/pkg/util/proto"
+)
+
+const (
+	// groupVersionKindExtensionKey is the key used to lookup the
+	// GroupVersionKind value for an object definition from the
+	// definition's "extensions" map.
+	groupVersionKindExtensionKey = "x-kubernetes-group-version-kind"
+)
+
+// ToProtoSchema builds the proto formatted schema from an OpenAPI spec
+func ToProtoSchema(openAPIDefinitions *spec.Definitions, gvk schema.GroupVersionKind) (proto.Schema, error) {
+	openAPISpec := newMinimalValidOpenAPISpec()
+	openAPISpec.Definitions = *openAPIDefinitions
+
+	specBytes, err := json.MarshalIndent(openAPISpec, " ", " ")
+	if err != nil {
+		return nil, err
+	}
+
+	var info yaml.MapSlice
+	err = yaml.Unmarshal(specBytes, &info)
+	if err != nil {
+		return nil, err
+	}
+
+	doc, err := openapi_v2.NewDocument(info, compiler.NewContext("$root", nil))
+	if err != nil {
+		return nil, err
+	}
+
+	models, err := proto.NewOpenAPIData(doc)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, modelName := range models.ListModels() {
+		model := models.LookupModel(modelName)
+		if model == nil {
+			return nil, fmt.Errorf("the ListModels function returned a model that can't be looked-up")
+		}
+		gvkList := parseGroupVersionKind(model)
+		for _, modelGVK := range gvkList {
+			if modelGVK == gvk {
+				return model, nil
+			}
+		}
+	}
+
+	return nil, fmt.Errorf("no model found with a %v tag matching %v", groupVersionKindExtensionKey, gvk)
+}
+
+// newMinimalValidOpenAPISpec creates a minimal openapi spec with only the required fields filled in
+func newMinimalValidOpenAPISpec() *spec.Swagger {
+	return &spec.Swagger{
+		SwaggerProps: spec.SwaggerProps{
+			Swagger: "2.0",
+			Info: &spec.Info{
+				InfoProps: spec.InfoProps{
+					Title:   "Kubernetes",
+					Version: "0.0.0",
+				},
+			},
+		},
+	}
+}
+
+// parseGroupVersionKind gets and parses GroupVersionKind from the extension. Returns empty if it doesn't have one.
+func parseGroupVersionKind(s proto.Schema) []schema.GroupVersionKind {
+	extensions := s.GetExtensions()
+
+	gvkListResult := []schema.GroupVersionKind{}
+
+	// Get the extensions
+	gvkExtension, ok := extensions[groupVersionKindExtensionKey]
+	if !ok {
+		return []schema.GroupVersionKind{}
+	}
+
+	// gvk extension must be a list of at least 1 element.
+	gvkList, ok := gvkExtension.([]interface{})
+	if !ok {
+		return []schema.GroupVersionKind{}
+	}
+
+	for _, gvk := range gvkList {
+		// gvk extension list must be a map with group, version, and
+		// kind fields
+		gvkMap, ok := gvk.(map[interface{}]interface{})
+		if !ok {
+			continue
+		}
+		group, ok := gvkMap["group"].(string)
+		if !ok {
+			continue
+		}
+		version, ok := gvkMap["version"].(string)
+		if !ok {
+			continue
+		}
+		kind, ok := gvkMap["kind"].(string)
+		if !ok {
+			continue
+		}
+
+		gvkListResult = append(gvkListResult, schema.GroupVersionKind{
+			Group:   group,
+			Version: version,
+			Kind:    kind,
+		})
+	}
+
+	return gvkListResult
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/trace/trace.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/trace/trace.go
new file mode 100644
index 0000000..b2f31c5
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/trace/trace.go
@@ -0,0 +1,89 @@
+/*
+Copyright 2015 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 trace
+
+import (
+	"bytes"
+	"fmt"
+	"math/rand"
+	"time"
+
+	"github.com/golang/glog"
+)
+
+type traceStep struct {
+	stepTime time.Time
+	msg      string
+}
+
+type Trace struct {
+	name      string
+	startTime time.Time
+	steps     []traceStep
+}
+
+func New(name string) *Trace {
+	return &Trace{name, time.Now(), nil}
+}
+
+func (t *Trace) Step(msg string) {
+	if t.steps == nil {
+		// traces almost always have less than 6 steps, do this to avoid more than a single allocation
+		t.steps = make([]traceStep, 0, 6)
+	}
+	t.steps = append(t.steps, traceStep{time.Now(), msg})
+}
+
+func (t *Trace) Log() {
+	// an explicit logging request should dump all the steps out at the higher level
+	t.logWithStepThreshold(0)
+}
+
+func (t *Trace) logWithStepThreshold(stepThreshold time.Duration) {
+	var buffer bytes.Buffer
+	tracenum := rand.Int31()
+	endTime := time.Now()
+
+	totalTime := endTime.Sub(t.startTime)
+	buffer.WriteString(fmt.Sprintf("Trace[%d]: %q (started: %v) (total time: %v):\n", tracenum, t.name, t.startTime, totalTime))
+	lastStepTime := t.startTime
+	for _, step := range t.steps {
+		stepDuration := step.stepTime.Sub(lastStepTime)
+		if stepThreshold == 0 || stepDuration > stepThreshold || glog.V(4) {
+			buffer.WriteString(fmt.Sprintf("Trace[%d]: [%v] [%v] %v\n", tracenum, step.stepTime.Sub(t.startTime), stepDuration, step.msg))
+		}
+		lastStepTime = step.stepTime
+	}
+	stepDuration := endTime.Sub(lastStepTime)
+	if stepThreshold == 0 || stepDuration > stepThreshold || glog.V(4) {
+		buffer.WriteString(fmt.Sprintf("Trace[%d]: [%v] [%v] END\n", tracenum, endTime.Sub(t.startTime), stepDuration))
+	}
+
+	glog.Info(buffer.String())
+}
+
+func (t *Trace) LogIfLong(threshold time.Duration) {
+	if time.Since(t.startTime) >= threshold {
+		// if any step took more than it's share of the total allowed time, it deserves a higher log level
+		stepThreshold := threshold / time.Duration(len(t.steps)+1)
+		t.logWithStepThreshold(stepThreshold)
+	}
+}
+
+func (t *Trace) TotalTime() time.Duration {
+	return time.Since(t.startTime)
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/webhook/gencerts.sh b/metrics-server/vendor/k8s.io/apiserver/pkg/util/webhook/gencerts.sh
new file mode 100755
index 0000000..a042ab6
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/webhook/gencerts.sh
@@ -0,0 +1,107 @@
+#!/usr/bin/env bash
+
+# Copyright 2017 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.
+
+set -e
+
+# gencerts.sh generates the certificates for the webhook tests.
+#
+# It is not expected to be run often (there is no go generate rule), and mainly
+# exists for documentation purposes.
+
+CN_BASE="webhook_tests"
+
+cat > server.conf << EOF
+[req]
+req_extensions = v3_req
+distinguished_name = req_distinguished_name
+[req_distinguished_name]
+[ v3_req ]
+basicConstraints = CA:FALSE
+keyUsage = nonRepudiation, digitalSignature, keyEncipherment
+extendedKeyUsage = clientAuth, serverAuth
+subjectAltName = @alt_names
+[alt_names]
+IP.1 = 127.0.0.1
+EOF
+
+cat > client.conf << EOF
+[req]
+req_extensions = v3_req
+distinguished_name = req_distinguished_name
+[req_distinguished_name]
+[ v3_req ]
+basicConstraints = CA:FALSE
+keyUsage = nonRepudiation, digitalSignature, keyEncipherment
+extendedKeyUsage = clientAuth, serverAuth
+subjectAltName = @alt_names
+[alt_names]
+IP.1 = 127.0.0.1
+EOF
+
+# Create a certificate authority
+openssl genrsa -out caKey.pem 2048
+openssl req -x509 -new -nodes -key caKey.pem -days 100000 -out caCert.pem -subj "/CN=${CN_BASE}_ca"
+
+# Create a second certificate authority
+openssl genrsa -out badCAKey.pem 2048
+openssl req -x509 -new -nodes -key badCAKey.pem -days 100000 -out badCACert.pem -subj "/CN=${CN_BASE}_ca"
+
+# Create a server certiticate
+openssl genrsa -out serverKey.pem 2048
+openssl req -new -key serverKey.pem -out server.csr -subj "/CN=${CN_BASE}_server" -config server.conf
+openssl x509 -req -in server.csr -CA caCert.pem -CAkey caKey.pem -CAcreateserial -out serverCert.pem -days 100000 -extensions v3_req -extfile server.conf
+
+# Create a client certiticate
+openssl genrsa -out clientKey.pem 2048
+openssl req -new -key clientKey.pem -out client.csr -subj "/CN=${CN_BASE}_client" -config client.conf
+openssl x509 -req -in client.csr -CA caCert.pem -CAkey caKey.pem -CAcreateserial -out clientCert.pem -days 100000 -extensions v3_req -extfile client.conf
+
+outfile=certs_test.go
+
+cat > $outfile << EOF
+/*
+Copyright 2017 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.
+*/
+
+EOF
+
+echo "// This file was generated using openssl by the gencerts.sh script" >> $outfile
+echo "// and holds raw certificates for the webhook tests." >> $outfile
+echo "" >> $outfile
+echo "package webhook" >> $outfile
+for file in caKey caCert badCAKey badCACert serverKey serverCert clientKey clientCert; do
+	data=$(cat ${file}.pem)
+	echo "" >> $outfile
+	echo "var $file = []byte(\`$data\`)" >> $outfile
+done
+
+# Clean up after we're done.
+rm *.pem
+rm *.csr
+rm *.srl
+rm *.conf
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/webhook/webhook.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/webhook/webhook.go
new file mode 100755
index 0000000..3b03fd3
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/webhook/webhook.go
@@ -0,0 +1,120 @@
+/*
+Copyright 2016 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 webhook implements a generic HTTP webhook plugin.
+package webhook
+
+import (
+	"fmt"
+	"time"
+
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/runtime/serializer"
+	"k8s.io/apimachinery/pkg/util/net"
+	"k8s.io/apimachinery/pkg/util/wait"
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+)
+
+// defaultRequestTimeout is set for all webhook request. This is the absolute
+// timeout of the HTTP request, including reading the response body.
+const defaultRequestTimeout = 30 * time.Second
+
+type GenericWebhook struct {
+	RestClient     *rest.RESTClient
+	initialBackoff time.Duration
+}
+
+// NewGenericWebhook creates a new GenericWebhook from the provided kubeconfig file.
+func NewGenericWebhook(scheme *runtime.Scheme, codecFactory serializer.CodecFactory, kubeConfigFile string, groupVersions []schema.GroupVersion, initialBackoff time.Duration) (*GenericWebhook, error) {
+	return newGenericWebhook(scheme, codecFactory, kubeConfigFile, groupVersions, initialBackoff, defaultRequestTimeout)
+}
+
+func newGenericWebhook(scheme *runtime.Scheme, codecFactory serializer.CodecFactory, kubeConfigFile string, groupVersions []schema.GroupVersion, initialBackoff, requestTimeout time.Duration) (*GenericWebhook, error) {
+	for _, groupVersion := range groupVersions {
+		if !scheme.IsVersionRegistered(groupVersion) {
+			return nil, fmt.Errorf("webhook plugin requires enabling extension resource: %s", groupVersion)
+		}
+	}
+
+	loadingRules := clientcmd.NewDefaultClientConfigLoadingRules()
+	loadingRules.ExplicitPath = kubeConfigFile
+	loader := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(loadingRules, &clientcmd.ConfigOverrides{})
+
+	clientConfig, err := loader.ClientConfig()
+	if err != nil {
+		return nil, err
+	}
+
+	// Kubeconfigs can't set a timeout, this can only be set through a command line flag.
+	//
+	// https://github.com/kubernetes/client-go/blob/master/tools/clientcmd/overrides.go
+	//
+	// Set this to something reasonable so request to webhooks don't hang forever.
+	clientConfig.Timeout = requestTimeout
+
+	codec := codecFactory.LegacyCodec(groupVersions...)
+	clientConfig.ContentConfig.NegotiatedSerializer = serializer.NegotiatedSerializerWrapper(runtime.SerializerInfo{Serializer: codec})
+
+	restClient, err := rest.UnversionedRESTClientFor(clientConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	return &GenericWebhook{restClient, initialBackoff}, nil
+}
+
+// WithExponentialBackoff will retry webhookFn() up to 5 times with exponentially increasing backoff when
+// it returns an error for which apierrors.SuggestsClientDelay() or apierrors.IsInternalError() returns true.
+func (g *GenericWebhook) WithExponentialBackoff(webhookFn func() rest.Result) rest.Result {
+	var result rest.Result
+	WithExponentialBackoff(g.initialBackoff, func() error {
+		result = webhookFn()
+		return result.Error()
+	})
+	return result
+}
+
+// WithExponentialBackoff will retry webhookFn() up to 5 times with exponentially increasing backoff when
+// it returns an error for which apierrors.SuggestsClientDelay() or apierrors.IsInternalError() returns true.
+func WithExponentialBackoff(initialBackoff time.Duration, webhookFn func() error) error {
+	backoff := wait.Backoff{
+		Duration: initialBackoff,
+		Factor:   1.5,
+		Jitter:   0.2,
+		Steps:    5,
+	}
+
+	var err error
+	wait.ExponentialBackoff(backoff, func() (bool, error) {
+		err = webhookFn()
+		// these errors indicate a transient error that should be retried.
+		if net.IsConnectionReset(err) || apierrors.IsInternalError(err) || apierrors.IsTimeout(err) || apierrors.IsTooManyRequests(err) {
+			return false, nil
+		}
+		// if the error sends the Retry-After header, we respect it as an explicit confirmation we should retry.
+		if _, shouldRetry := apierrors.SuggestsClientDelay(err); shouldRetry {
+			return false, nil
+		}
+		if err != nil {
+			return false, err
+		}
+		return true, nil
+	})
+	return err
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/wsstream/conn.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/wsstream/conn.go
new file mode 100644
index 0000000..6f26b22
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/wsstream/conn.go
@@ -0,0 +1,352 @@
+/*
+Copyright 2015 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 wsstream
+
+import (
+	"encoding/base64"
+	"fmt"
+	"io"
+	"net/http"
+	"regexp"
+	"strings"
+	"time"
+
+	"github.com/golang/glog"
+	"golang.org/x/net/websocket"
+
+	"k8s.io/apimachinery/pkg/util/runtime"
+)
+
+// The Websocket subprotocol "channel.k8s.io" prepends each binary message with a byte indicating
+// the channel number (zero indexed) the message was sent on. Messages in both directions should
+// prefix their messages with this channel byte. When used for remote execution, the channel numbers
+// are by convention defined to match the POSIX file-descriptors assigned to STDIN, STDOUT, and STDERR
+// (0, 1, and 2). No other conversion is performed on the raw subprotocol - writes are sent as they
+// are received by the server.
+//
+// Example client session:
+//
+//    CONNECT http://server.com with subprotocol "channel.k8s.io"
+//    WRITE []byte{0, 102, 111, 111, 10} # send "foo\n" on channel 0 (STDIN)
+//    READ  []byte{1, 10}                # receive "\n" on channel 1 (STDOUT)
+//    CLOSE
+//
+const ChannelWebSocketProtocol = "channel.k8s.io"
+
+// The Websocket subprotocol "base64.channel.k8s.io" base64 encodes each message with a character
+// indicating the channel number (zero indexed) the message was sent on. Messages in both directions
+// should prefix their messages with this channel char. When used for remote execution, the channel
+// numbers are by convention defined to match the POSIX file-descriptors assigned to STDIN, STDOUT,
+// and STDERR ('0', '1', and '2'). The data received on the server is base64 decoded (and must be
+// be valid) and data written by the server to the client is base64 encoded.
+//
+// Example client session:
+//
+//    CONNECT http://server.com with subprotocol "base64.channel.k8s.io"
+//    WRITE []byte{48, 90, 109, 57, 118, 67, 103, 111, 61} # send "foo\n" (base64: "Zm9vCgo=") on channel '0' (STDIN)
+//    READ  []byte{49, 67, 103, 61, 61} # receive "\n" (base64: "Cg==") on channel '1' (STDOUT)
+//    CLOSE
+//
+const Base64ChannelWebSocketProtocol = "base64.channel.k8s.io"
+
+type codecType int
+
+const (
+	rawCodec codecType = iota
+	base64Codec
+)
+
+type ChannelType int
+
+const (
+	IgnoreChannel ChannelType = iota
+	ReadChannel
+	WriteChannel
+	ReadWriteChannel
+)
+
+var (
+	// connectionUpgradeRegex matches any Connection header value that includes upgrade
+	connectionUpgradeRegex = regexp.MustCompile("(^|.*,\\s*)upgrade($|\\s*,)")
+)
+
+// IsWebSocketRequest returns true if the incoming request contains connection upgrade headers
+// for WebSockets.
+func IsWebSocketRequest(req *http.Request) bool {
+	if !strings.EqualFold(req.Header.Get("Upgrade"), "websocket") {
+		return false
+	}
+	return connectionUpgradeRegex.MatchString(strings.ToLower(req.Header.Get("Connection")))
+}
+
+// IgnoreReceives reads from a WebSocket until it is closed, then returns. If timeout is set, the
+// read and write deadlines are pushed every time a new message is received.
+func IgnoreReceives(ws *websocket.Conn, timeout time.Duration) {
+	defer runtime.HandleCrash()
+	var data []byte
+	for {
+		resetTimeout(ws, timeout)
+		if err := websocket.Message.Receive(ws, &data); err != nil {
+			return
+		}
+	}
+}
+
+// handshake ensures the provided user protocol matches one of the allowed protocols. It returns
+// no error if no protocol is specified.
+func handshake(config *websocket.Config, req *http.Request, allowed []string) error {
+	protocols := config.Protocol
+	if len(protocols) == 0 {
+		protocols = []string{""}
+	}
+
+	for _, protocol := range protocols {
+		for _, allow := range allowed {
+			if allow == protocol {
+				config.Protocol = []string{protocol}
+				return nil
+			}
+		}
+	}
+
+	return fmt.Errorf("requested protocol(s) are not supported: %v; supports %v", config.Protocol, allowed)
+}
+
+// ChannelProtocolConfig describes a websocket subprotocol with channels.
+type ChannelProtocolConfig struct {
+	Binary   bool
+	Channels []ChannelType
+}
+
+// NewDefaultChannelProtocols returns a channel protocol map with the
+// subprotocols "", "channel.k8s.io", "base64.channel.k8s.io" and the given
+// channels.
+func NewDefaultChannelProtocols(channels []ChannelType) map[string]ChannelProtocolConfig {
+	return map[string]ChannelProtocolConfig{
+		"": {Binary: true, Channels: channels},
+		ChannelWebSocketProtocol:       {Binary: true, Channels: channels},
+		Base64ChannelWebSocketProtocol: {Binary: false, Channels: channels},
+	}
+}
+
+// Conn supports sending multiple binary channels over a websocket connection.
+type Conn struct {
+	protocols        map[string]ChannelProtocolConfig
+	selectedProtocol string
+	channels         []*websocketChannel
+	codec            codecType
+	ready            chan struct{}
+	ws               *websocket.Conn
+	timeout          time.Duration
+}
+
+// NewConn creates a WebSocket connection that supports a set of channels. Channels begin each
+// web socket message with a single byte indicating the channel number (0-N). 255 is reserved for
+// future use. The channel types for each channel are passed as an array, supporting the different
+// duplex modes. Read and Write refer to whether the channel can be used as a Reader or Writer.
+//
+// The protocols parameter maps subprotocol names to ChannelProtocols. The empty string subprotocol
+// name is used if websocket.Config.Protocol is empty.
+func NewConn(protocols map[string]ChannelProtocolConfig) *Conn {
+	return &Conn{
+		ready:     make(chan struct{}),
+		protocols: protocols,
+	}
+}
+
+// SetIdleTimeout sets the interval for both reads and writes before timeout. If not specified,
+// there is no timeout on the connection.
+func (conn *Conn) SetIdleTimeout(duration time.Duration) {
+	conn.timeout = duration
+}
+
+// Open the connection and create channels for reading and writing. It returns
+// the selected subprotocol, a slice of channels and an error.
+func (conn *Conn) Open(w http.ResponseWriter, req *http.Request) (string, []io.ReadWriteCloser, error) {
+	go func() {
+		defer runtime.HandleCrash()
+		defer conn.Close()
+		websocket.Server{Handshake: conn.handshake, Handler: conn.handle}.ServeHTTP(w, req)
+	}()
+	<-conn.ready
+	rwc := make([]io.ReadWriteCloser, len(conn.channels))
+	for i := range conn.channels {
+		rwc[i] = conn.channels[i]
+	}
+	return conn.selectedProtocol, rwc, nil
+}
+
+func (conn *Conn) initialize(ws *websocket.Conn) {
+	negotiated := ws.Config().Protocol
+	conn.selectedProtocol = negotiated[0]
+	p := conn.protocols[conn.selectedProtocol]
+	if p.Binary {
+		conn.codec = rawCodec
+	} else {
+		conn.codec = base64Codec
+	}
+	conn.ws = ws
+	conn.channels = make([]*websocketChannel, len(p.Channels))
+	for i, t := range p.Channels {
+		switch t {
+		case ReadChannel:
+			conn.channels[i] = newWebsocketChannel(conn, byte(i), true, false)
+		case WriteChannel:
+			conn.channels[i] = newWebsocketChannel(conn, byte(i), false, true)
+		case ReadWriteChannel:
+			conn.channels[i] = newWebsocketChannel(conn, byte(i), true, true)
+		case IgnoreChannel:
+			conn.channels[i] = newWebsocketChannel(conn, byte(i), false, false)
+		}
+	}
+
+	close(conn.ready)
+}
+
+func (conn *Conn) handshake(config *websocket.Config, req *http.Request) error {
+	supportedProtocols := make([]string, 0, len(conn.protocols))
+	for p := range conn.protocols {
+		supportedProtocols = append(supportedProtocols, p)
+	}
+	return handshake(config, req, supportedProtocols)
+}
+
+func (conn *Conn) resetTimeout() {
+	if conn.timeout > 0 {
+		conn.ws.SetDeadline(time.Now().Add(conn.timeout))
+	}
+}
+
+// Close is only valid after Open has been called
+func (conn *Conn) Close() error {
+	<-conn.ready
+	for _, s := range conn.channels {
+		s.Close()
+	}
+	conn.ws.Close()
+	return nil
+}
+
+// handle implements a websocket handler.
+func (conn *Conn) handle(ws *websocket.Conn) {
+	defer conn.Close()
+	conn.initialize(ws)
+
+	for {
+		conn.resetTimeout()
+		var data []byte
+		if err := websocket.Message.Receive(ws, &data); err != nil {
+			if err != io.EOF {
+				glog.Errorf("Error on socket receive: %v", err)
+			}
+			break
+		}
+		if len(data) == 0 {
+			continue
+		}
+		channel := data[0]
+		if conn.codec == base64Codec {
+			channel = channel - '0'
+		}
+		data = data[1:]
+		if int(channel) >= len(conn.channels) {
+			glog.V(6).Infof("Frame is targeted for a reader %d that is not valid, possible protocol error", channel)
+			continue
+		}
+		if _, err := conn.channels[channel].DataFromSocket(data); err != nil {
+			glog.Errorf("Unable to write frame to %d: %v\n%s", channel, err, string(data))
+			continue
+		}
+	}
+}
+
+// write multiplexes the specified channel onto the websocket
+func (conn *Conn) write(num byte, data []byte) (int, error) {
+	conn.resetTimeout()
+	switch conn.codec {
+	case rawCodec:
+		frame := make([]byte, len(data)+1)
+		frame[0] = num
+		copy(frame[1:], data)
+		if err := websocket.Message.Send(conn.ws, frame); err != nil {
+			return 0, err
+		}
+	case base64Codec:
+		frame := string('0'+num) + base64.StdEncoding.EncodeToString(data)
+		if err := websocket.Message.Send(conn.ws, frame); err != nil {
+			return 0, err
+		}
+	}
+	return len(data), nil
+}
+
+// websocketChannel represents a channel in a connection
+type websocketChannel struct {
+	conn *Conn
+	num  byte
+	r    io.Reader
+	w    io.WriteCloser
+
+	read, write bool
+}
+
+// newWebsocketChannel creates a pipe for writing to a websocket. Do not write to this pipe
+// prior to the connection being opened. It may be no, half, or full duplex depending on
+// read and write.
+func newWebsocketChannel(conn *Conn, num byte, read, write bool) *websocketChannel {
+	r, w := io.Pipe()
+	return &websocketChannel{conn, num, r, w, read, write}
+}
+
+func (p *websocketChannel) Write(data []byte) (int, error) {
+	if !p.write {
+		return len(data), nil
+	}
+	return p.conn.write(p.num, data)
+}
+
+// DataFromSocket is invoked by the connection receiver to move data from the connection
+// into a specific channel.
+func (p *websocketChannel) DataFromSocket(data []byte) (int, error) {
+	if !p.read {
+		return len(data), nil
+	}
+
+	switch p.conn.codec {
+	case rawCodec:
+		return p.w.Write(data)
+	case base64Codec:
+		dst := make([]byte, len(data))
+		n, err := base64.StdEncoding.Decode(dst, data)
+		if err != nil {
+			return 0, err
+		}
+		return p.w.Write(dst[:n])
+	}
+	return 0, nil
+}
+
+func (p *websocketChannel) Read(data []byte) (int, error) {
+	if !p.read {
+		return 0, io.EOF
+	}
+	return p.r.Read(data)
+}
+
+func (p *websocketChannel) Close() error {
+	return p.w.Close()
+}
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/wsstream/doc.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/wsstream/doc.go
new file mode 100644
index 0000000..694ce81
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/wsstream/doc.go
@@ -0,0 +1,21 @@
+/*
+Copyright 2015 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 wsstream contains utilities for streaming content over WebSockets.
+// The Conn type allows callers to multiplex multiple read/write channels over
+// a single websocket. The Reader type allows an io.Reader to be copied over
+// a websocket channel as binary content.
+package wsstream // import "k8s.io/apiserver/pkg/util/wsstream"
diff --git a/metrics-server/vendor/k8s.io/apiserver/pkg/util/wsstream/stream.go b/metrics-server/vendor/k8s.io/apiserver/pkg/util/wsstream/stream.go
new file mode 100644
index 0000000..9dd165b
--- /dev/null
+++ b/metrics-server/vendor/k8s.io/apiserver/pkg/util/wsstream/stream.go
@@ -0,0 +1,177 @@
+/*
+Copyright 2015 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 wsstream
+
+import (
+	"encoding/base64"
+	"io"
+	"net/http"
+	"sync"
+	"time"
+
+	"golang.org/x/net/websocket"
+
+	"k8s.io/apimachinery/pkg/util/runtime"
+)
+
+// The WebSocket subprotocol "binary.k8s.io" will only send messages to the
+// client and ignore messages sent to the server. The received messages are
+// the exact bytes written to the stream. Zero byte messages are possible.
+const binaryWebSocketProtocol = "binary.k8s.io"
+
+// The WebSocket subprotocol "base64.binary.k8s.io" will only send messages to the
+// client and ignore messages sent to the server. The received messages are
+// a base64 version of the bytes written to the stream. Zero byte messages are
+// possible.
+const base64BinaryWebSocketProtocol = "base64.binary.k8s.io"
+
+// ReaderProtocolConfig describes a websocket subprotocol with one stream.
+type ReaderProtocolConfig struct {
+	Binary bool
+}
+
+// NewDefaultReaderProtocols returns a stream protocol map with the
+// subprotocols "", "channel.k8s.io", "base64.channel.k8s.io".
+func NewDefaultReaderProtocols() map[string]ReaderProtocolConfig {
+	return map[string]ReaderProtocolConfig{
+		"": {Binary: true},
+		binaryWebSocketProtocol:       {Binary: true},
+		base64BinaryWebSocketProtocol: {Binary: false},
+	}
+}
+
+// Reader supports returning an arbitrary byte stream over a websocket channel.
+type Reader struct {
+	err              chan error
+	r                io.Reader
+	ping             bool
+	timeout          time.Duration
+	protocols        map[string]ReaderProtocolConfig
+	selectedProtocol string
+
+	handleCrash func() // overridable for testing
+}
+
+// NewReader creates a WebSocket pipe that will copy the contents of r to a provided
+// WebSocket connection. If ping is true, a zero length message will be sent to the client
+// before the stream begins reading.
+//
+// The protocols parameter maps subprotocol names to StreamProtocols. The empty string
+// subprotocol name is used if websocket.Config.Protocol is empty.
+func NewReader(r io.Reader, ping bool, protocols map[string]ReaderProtocolConfig) *Reader {
+	return &Reader{
+		r:           r,
+		err:         make(chan error),
+		ping:        ping,
+		protocols:   protocols,
+		handleCrash: func() { runtime.HandleCrash() },
+	}
+}
+
+// SetIdleTimeout sets the interval for both reads and writes before timeout. If not specified,
+// there is no timeout on the reader.
+func (r *Reader) SetIdleTimeout(duration time.Duration) {
+	r.timeout = duration
+}
+
+func (r *Reader) handshake(config *websocket.Config, req *http.Request) error {
+	supportedProtocols := make([]string, 0, len(r.protocols))
+	for p := range r.protocols {
+		supportedProtocols = append(supportedProtocols, p)
+	}
+	return handshake(config, req, supportedProtocols)
+}
+
+// Copy the reader to the response. The created WebSocket is closed after this
+// method completes.
+func (r *Reader) Copy(w http.ResponseWriter, req *http.Request) error {
+	go func() {
+		defer r.handleCrash()
+		websocket.Server{Handshake: r.handshake, Handler: r.handle}.ServeHTTP(w, req)
+	}()
+	return <-r.err
+}
+
+// handle implements a WebSocket handler.
+func (r *Reader) handle(ws *websocket.Conn) {
+	// Close the connection when the client requests it, or when we finish streaming, whichever happens first
+	closeConnOnce := &sync.Once{}
+	closeConn := func() {
+		closeConnOnce.Do(func() {
+			ws.Close()
+		})
+	}
+
+	negotiated := ws.Config().Protocol
+	r.selectedProtocol = negotiated[0]
+	defer close(r.err)
+	defer closeConn()
+
+	go func() {
+		defer runtime.HandleCrash()
+		// This blocks until the connection is closed.
+		// Client should not send anything.
+		IgnoreReceives(ws, r.timeout)
+		// Once the client closes, we should also close
+		closeConn()
+	}()
+
+	r.err <- messageCopy(ws, r.r, !r.protocols[r.selectedProtocol].Binary, r.ping, r.timeout)
+}
+
+func resetTimeout(ws *websocket.Conn, timeout time.Duration) {
+	if timeout > 0 {
+		ws.SetDeadline(time.Now().Add(timeout))
+	}
+}
+
+func messageCopy(ws *websocket.Conn, r io.Reader, base64Encode, ping bool, timeout time.Duration) error {
+	buf := make([]byte, 2048)
+	if ping {
+		resetTimeout(ws, timeout)
+		if base64Encode {
+			if err := websocket.Message.Send(ws, ""); err != nil {
+				return err
+			}
+		} else {
+			if err := websocket.Message.Send(ws, []byte{}); err != nil {
+				return err
+			}
+		}
+	}
+	for {
+		resetTimeout(ws, timeout)
+		n, err := r.Read(buf)
+		if err != nil {
+			if err == io.EOF {
+				return nil
+			}
+			return err
+		}
+		if n > 0 {
+			if base64Encode {
+				if err := websocket.Message.Send(ws, base64.StdEncoding.EncodeToString(buf[:n])); err != nil {
+					return err
+				}
+			} else {
+				if err := websocket.Message.Send(ws, buf[:n]); err != nil {
+					return err
+				}
+			}
+		}
+	}
+}