Update dependencies to v0.23.16-rc.0 tag

cherry pick pr #111557 to 1.23 :update smd to 4.2.3

Kubernetes-commit: 5f01bb40bcee9c5f16f08fe9a2fe5a39beb81101

applyconfigurations/core/v1/probehandler.go

@@ -24,7 +24,7 @@ type ProbeHandlerApplyConfiguration struct {
 	Exec      *ExecActionApplyConfiguration      `json:"exec,omitempty"`
 	HTTPGet   *HTTPGetActionApplyConfiguration   `json:"httpGet,omitempty"`
 	TCPSocket *TCPSocketActionApplyConfiguration `json:"tcpSocket,omitempty"`
-	GRPC      *GRPCActionApplyConfiguration      `json:"gRPC,omitempty"`
+	GRPC      *GRPCActionApplyConfiguration      `json:"grpc,omitempty"`
 }
 
 // ProbeHandlerApplyConfiguration constructs an declarative configuration of the ProbeHandler type for use with

applyconfigurations/internal/internal.go

@@ -5984,7 +5984,7 @@ var schemaYAML = typed.YAMLObject(`types:
     - name: failureThreshold
       type:
         scalar: numeric
-    - name: gRPC
+    - name: grpc
       type:
         namedType: io.k8s.api.core.v1.GRPCAction
     - name: httpGet

go.mod

@@ -23,23 +23,23 @@ require (
 	github.com/imdario/mergo v0.3.5
 	github.com/peterbourgon/diskv v2.0.1+incompatible
 	github.com/spf13/pflag v1.0.5
-	github.com/stretchr/testify v1.7.0
+	github.com/stretchr/testify v1.8.0
 	golang.org/x/crypto v0.0.0-20210817164053-32db794688a5 // indirect
-	golang.org/x/net v0.0.0-20210825183410-e898025ed96a
+	golang.org/x/net v0.0.0-20211209124913-491a49abca63
 	golang.org/x/oauth2 v0.0.0-20210819190943-2bc19b11175f
 	golang.org/x/term v0.0.0-20210615171337-6886f2dfbf5b
 	golang.org/x/time v0.0.0-20210723032227-1f47c861a9ac
 	google.golang.org/protobuf v1.27.1
-	k8s.io/api v0.0.0-20211124232210-4c321cf829a0
-	k8s.io/apimachinery v0.0.0-20211124232001-ffb9472ec51a
+	k8s.io/api v0.23.16-rc.0
+	k8s.io/apimachinery v0.23.16-rc.0
 	k8s.io/klog/v2 v2.30.0
 	k8s.io/kube-openapi v0.0.0-20211115234752-e816edb12b65
-	k8s.io/utils v0.0.0-20210930125809-cb0fa318a74b
-	sigs.k8s.io/structured-merge-diff/v4 v4.1.2
+	k8s.io/utils v0.0.0-20211116205334-6203023598ed
+	sigs.k8s.io/structured-merge-diff/v4 v4.2.3
 	sigs.k8s.io/yaml v1.2.0
 )
 
 replace (
-	k8s.io/api => k8s.io/api v0.0.0-20211124232210-4c321cf829a0
-	k8s.io/apimachinery => k8s.io/apimachinery v0.0.0-20211124232001-ffb9472ec51a
+	k8s.io/api => k8s.io/api v0.23.16-rc.0
+	k8s.io/apimachinery => k8s.io/apimachinery v0.23.16-rc.0
 )

go.sum

@@ -238,12 +238,14 @@ github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/stoewer/go-strcase v1.2.0/go.mod h1:IBiWB2sKIp3wVVQ3Y035++gc+knqhUQag1KpM8ahLw8=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
-github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/yuin/goldmark v1.1.25/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.1.32/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
@@ -335,8 +337,8 @@ golang.org/x/net v0.0.0-20210119194325-5f4716e94777/go.mod h1:m0MpNAwzfU5UDzcl9v
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20210316092652-d523dce5a7f4/go.mod h1:RBQZq4jEuRlivfhVLdyRGr576XBO4/greRjx4P4O3yc=
 golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
-golang.org/x/net v0.0.0-20210825183410-e898025ed96a h1:bRuuGXV8wwSdGTB+CtJf+FjgO1APK1CoO39T4BN/XBw=
-golang.org/x/net v0.0.0-20210825183410-e898025ed96a/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20211209124913-491a49abca63 h1:iocB37TsdFuN6IBRZ+ry36wrkoV51/tl5vOWqkcPGvY=
+golang.org/x/net v0.0.0-20211209124913-491a49abca63/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
@@ -601,8 +603,9 @@ gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
 gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 honnef.co/go/tools v0.0.0-20190102054323-c2f93a96b099/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
 honnef.co/go/tools v0.0.0-20190106161140-3f1c8253044a/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
 honnef.co/go/tools v0.0.0-20190418001031-e561f6794a2a/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
@@ -610,10 +613,10 @@ honnef.co/go/tools v0.0.0-20190523083050-ea95bdfd59fc/go.mod h1:rf3lG4BRIbNafJWh
 honnef.co/go/tools v0.0.1-2019.2.3/go.mod h1:a3bituU0lyd329TUQxRnasdCoJDkEUEAqEt0JzvZhAg=
 honnef.co/go/tools v0.0.1-2020.1.3/go.mod h1:X/FiERA/W4tHapMX5mGpAtMSVEeEUOyHaw9vFzvIQ3k=
 honnef.co/go/tools v0.0.1-2020.1.4/go.mod h1:X/FiERA/W4tHapMX5mGpAtMSVEeEUOyHaw9vFzvIQ3k=
-k8s.io/api v0.0.0-20211124232210-4c321cf829a0 h1:hTJnV20bAHUQZIzigjK3CvWqQuzeQP/C7AP72fzzEIo=
-k8s.io/api v0.0.0-20211124232210-4c321cf829a0/go.mod h1:Iod80qmyxDiUr9X93OyKup/yGuYZGx8VK8nLuWpK9Yc=
-k8s.io/apimachinery v0.0.0-20211124232001-ffb9472ec51a h1:IggksFfccO+DgJNByne5JOJ+jfqpcMZRsYkwYGZ6qkA=
-k8s.io/apimachinery v0.0.0-20211124232001-ffb9472ec51a/go.mod h1:fFCTTBKvKcwTPFzjlcxp91uPFZr+JA0FubU4fLzzFYc=
+k8s.io/api v0.23.16-rc.0 h1:uX6LmrC8ThEpbBtAAbqjuB84QrP6zIGytwKIYTk8mI8=
+k8s.io/api v0.23.16-rc.0/go.mod h1:EZI/NGtoB69oae6KxTRoKrb7YNll1p9g37EYBZpa04Q=
+k8s.io/apimachinery v0.23.16-rc.0 h1:yqVmy4UHlkj+75kLWSb4rBsaDZgvL29kMKz/v4DPM9Q=
+k8s.io/apimachinery v0.23.16-rc.0/go.mod h1:mbefzm1H5rPdyibAc8rmzLAbr/oG60tDHQFj0FTqrZU=
 k8s.io/gengo v0.0.0-20210813121822-485abfe95c7c/go.mod h1:FiNAH4ZV3gBg2Kwh89tzAEV2be7d5xI0vBa/VySYy3E=
 k8s.io/klog/v2 v2.0.0/go.mod h1:PBfzABfn139FHAV07az/IF9Wp1bkk3vpT2XSJ76fSDE=
 k8s.io/klog/v2 v2.2.0/go.mod h1:Od+F08eJP+W3HUb4pSrPpgp9DGU4GzlpG/TmITuYh/Y=
@@ -622,15 +625,15 @@ k8s.io/klog/v2 v2.30.0/go.mod h1:y1WjHnz7Dj687irZUWR/WLkLc5N1YHtjLdmgWjndZn0=
 k8s.io/kube-openapi v0.0.0-20211115234752-e816edb12b65 h1:E3J9oCLlaobFUqsjG9DfKbP2BmgwBL2p7pn0A3dG9W4=
 k8s.io/kube-openapi v0.0.0-20211115234752-e816edb12b65/go.mod h1:sX9MT8g7NVZM5lVL/j8QyCCJe8YSMW30QvGZWaCIDIk=
 k8s.io/utils v0.0.0-20210802155522-efc7438f0176/go.mod h1:jPW/WVKK9YHAvNhRxK0md/EJ228hCsBRufyofKtW8HA=
-k8s.io/utils v0.0.0-20210930125809-cb0fa318a74b h1:wxEMGetGMur3J1xuGLQY7GEQYg9bZxKn3tKo5k/eYcs=
-k8s.io/utils v0.0.0-20210930125809-cb0fa318a74b/go.mod h1:jPW/WVKK9YHAvNhRxK0md/EJ228hCsBRufyofKtW8HA=
+k8s.io/utils v0.0.0-20211116205334-6203023598ed h1:ck1fRPWPJWsMd8ZRFsWc6mh/zHp5fZ/shhbrgPUxDAE=
+k8s.io/utils v0.0.0-20211116205334-6203023598ed/go.mod h1:jPW/WVKK9YHAvNhRxK0md/EJ228hCsBRufyofKtW8HA=
 rsc.io/binaryregexp v0.2.0/go.mod h1:qTv7/COck+e2FymRvadv62gMdZztPaShugOCi3I+8D8=
 rsc.io/quote/v3 v3.1.0/go.mod h1:yEA65RcK8LyAZtP9Kv3t0HmxON59tX3rD+tICJqUlj0=
 rsc.io/sampler v1.3.0/go.mod h1:T1hPZKmBbMNahiBKFy5HrXp6adAjACjK9JXDnKaTXpA=
 sigs.k8s.io/json v0.0.0-20211020170558-c049b76a60c6 h1:fD1pz4yfdADVNfFmcP2aBEtudwUQ1AlLnRBALr33v3s=
 sigs.k8s.io/json v0.0.0-20211020170558-c049b76a60c6/go.mod h1:p4QtZmO4uMYipTQNzagwnNoseA6OxSUutVw05NhYDRs=
 sigs.k8s.io/structured-merge-diff/v4 v4.0.2/go.mod h1:bJZC9H9iH24zzfZ/41RGcq60oK1F7G282QMXDPYydCw=
-sigs.k8s.io/structured-merge-diff/v4 v4.1.2 h1:Hr/htKFmJEbtMgS/UD0N+gtgctAqz81t3nu+sPzynno=
-sigs.k8s.io/structured-merge-diff/v4 v4.1.2/go.mod h1:j/nl6xW8vLS49O8YvXW1ocPhZawJtm+Yrr7PPRQ0Vg4=
+sigs.k8s.io/structured-merge-diff/v4 v4.2.3 h1:PRbqxJClWWYMNV1dhaG4NsibJbArud9kFxnAMREiWFE=
+sigs.k8s.io/structured-merge-diff/v4 v4.2.3/go.mod h1:qjx8mGObPmV2aSZepjQjbmb2ihdVs8cGKBraizNC69E=
 sigs.k8s.io/yaml v1.2.0 h1:kr/MCeFWJWTwyaHoR9c8EjH9OumOmoF9YGiZd7lFm/Q=
 sigs.k8s.io/yaml v1.2.0/go.mod h1:yfXDCHCao9+ENCvLSE62v9VSji2MKu5jeNfTrofGhJc=

kubernetes/clientset.go

@@ -413,6 +413,10 @@ func (c *Clientset) Discovery() discovery.DiscoveryInterface {
 func NewForConfig(c *rest.Config) (*Clientset, error) {
 	configShallowCopy := *c
 
+	if configShallowCopy.UserAgent == "" {
+		configShallowCopy.UserAgent = rest.DefaultKubernetesUserAgent()
+	}
+
 	// share the transport between all clients
 	httpClient, err := rest.HTTPClientFor(&configShallowCopy)
 	if err != nil {

kubernetes_test/clientset_test.go

@@ -0,0 +1,88 @@
+/*
+Copyright 2022 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 kubernetes_test
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/kubernetes/scheme"
+	"k8s.io/client-go/rest"
+)
+
+func TestClientUserAgent(t *testing.T) {
+	tests := []struct {
+		name      string
+		userAgent string
+		expect    string
+	}{
+		{
+			name:   "empty",
+			expect: rest.DefaultKubernetesUserAgent(),
+		},
+		{
+			name:      "custom",
+			userAgent: "test-agent",
+			expect:    "test-agent",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			ts := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				userAgent := r.Header.Get("User-Agent")
+				if userAgent != tc.expect {
+					t.Errorf("User Agent expected: %s got: %s", tc.expect, userAgent)
+					http.Error(w, "Unexpected user agent", http.StatusBadRequest)
+					return
+				}
+				w.Header().Set("Content-Type", "application/json")
+				w.Write([]byte("{}"))
+			}))
+			ts.Start()
+			defer ts.Close()
+
+			gv := v1.SchemeGroupVersion
+			config := &rest.Config{
+				Host: ts.URL,
+			}
+			config.GroupVersion = &gv
+			config.NegotiatedSerializer = scheme.Codecs.WithoutConversion()
+			config.UserAgent = tc.userAgent
+			config.ContentType = "application/json"
+
+			client, err := kubernetes.NewForConfig(config)
+			if err != nil {
+				t.Fatalf("failed to create REST client: %v", err)
+			}
+			_, err = client.CoreV1().Pods("").List(context.TODO(), metav1.ListOptions{})
+			if err != nil {
+				t.Error(err)
+			}
+			_, err = client.CoreV1().Secrets("").List(context.TODO(), metav1.ListOptions{})
+			if err != nil {
+				t.Error(err)
+			}
+		})
+	}
+
+}

pkg/version/.gitattributes

@@ -1 +0,0 @@
-base.go export-subst

plugin/pkg/client/auth/exec/exec.go

@@ -201,14 +201,18 @@ func newAuthenticator(c *cache, isTerminalFunc func(int) bool, config *api.ExecC
 		now:             time.Now,
 		environ:         os.Environ,
 
-		defaultDialer: defaultDialer,
-		connTracker:   connTracker,
+		connTracker: connTracker,
 	}
 
 	for _, env := range config.Env {
 		a.env = append(a.env, env.Name+"="+env.Value)
 	}
 
+	// these functions are made comparable and stored in the cache so that repeated clientset
+	// construction with the same rest.Config results in a single TLS cache and Authenticator
+	a.getCert = &transport.GetCertHolder{GetCert: a.cert}
+	a.dial = &transport.DialHolder{Dial: defaultDialer.DialContext}
+
 	return c.put(key, a), nil
 }
 
@@ -263,8 +267,6 @@ type Authenticator struct {
 	now             func() time.Time
 	environ         func() []string
 
-	// defaultDialer is used for clients which don't specify a custom dialer
-	defaultDialer *connrotation.Dialer
 	// connTracker tracks all connections opened that we need to close when rotating a client certificate
 	connTracker *connrotation.ConnectionTracker
 
@@ -275,6 +277,12 @@ type Authenticator struct {
 	mu          sync.Mutex
 	cachedCreds *credentials
 	exp         time.Time
+
+	// getCert makes Authenticator.cert comparable to support TLS config caching
+	getCert *transport.GetCertHolder
+	// dial is used for clients which do not specify a custom dialer
+	// it is comparable to support TLS config caching
+	dial *transport.DialHolder
 }
 
 type credentials struct {
@@ -302,18 +310,20 @@ func (a *Authenticator) UpdateTransportConfig(c *transport.Config) error {
 	if c.TLS.GetCert != nil {
 		return errors.New("can't add TLS certificate callback: transport.Config.TLS.GetCert already set")
 	}
-	c.TLS.GetCert = a.cert
+	c.TLS.GetCert = a.getCert.GetCert
+	c.TLS.GetCertHolder = a.getCert // comparable for TLS config caching
 
-	var d *connrotation.Dialer
 	if c.Dial != nil {
 		// if c has a custom dialer, we have to wrap it
-		d = connrotation.NewDialerWithTracker(c.Dial, a.connTracker)
+		// TLS config caching is not supported for this config
+		d := connrotation.NewDialerWithTracker(c.Dial, a.connTracker)
+		c.Dial = d.DialContext
+		c.DialHolder = nil
 	} else {
-		d = a.defaultDialer
+		c.Dial = a.dial.Dial
+		c.DialHolder = a.dial // comparable for TLS config caching
 	}
 
-	c.Dial = d.DialContext
-
 	return nil
 }
 

plugin/pkg/client/auth/exec/exec_cache_test.go

@@ -0,0 +1,106 @@
+/*
+Copyright 2022 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 exec_test // separate package to prevent circular import
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	utilnet "k8s.io/apimachinery/pkg/util/net"
+	clientset "k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/rest"
+	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
+)
+
+// TestExecTLSCache asserts the semantics of the TLS cache when exec auth is used.
+//
+// In particular, when:
+//   - multiple identical rest configs exist as distinct objects, and
+//   - these rest configs use exec auth, and
+//   - these rest configs are used to create distinct clientsets, then
+//
+// the underlying TLS config is shared between those clientsets.
+func TestExecTLSCache(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	t.Cleanup(cancel)
+
+	config1 := &rest.Config{
+		Host: "https://localhost",
+		ExecProvider: &clientcmdapi.ExecConfig{
+			Command:         "./testdata/test-plugin.sh",
+			APIVersion:      "client.authentication.k8s.io/v1",
+			InteractiveMode: clientcmdapi.IfAvailableExecInteractiveMode,
+		},
+	}
+	client1 := clientset.NewForConfigOrDie(config1)
+
+	config2 := &rest.Config{
+		Host: "https://localhost",
+		ExecProvider: &clientcmdapi.ExecConfig{
+			Command:         "./testdata/test-plugin.sh",
+			APIVersion:      "client.authentication.k8s.io/v1",
+			InteractiveMode: clientcmdapi.IfAvailableExecInteractiveMode,
+		},
+	}
+	client2 := clientset.NewForConfigOrDie(config2)
+
+	config3 := &rest.Config{
+		Host: "https://localhost",
+		ExecProvider: &clientcmdapi.ExecConfig{
+			Command:         "./testdata/test-plugin.sh",
+			Args:            []string{"make this exec auth different"},
+			APIVersion:      "client.authentication.k8s.io/v1",
+			InteractiveMode: clientcmdapi.IfAvailableExecInteractiveMode,
+		},
+	}
+	client3 := clientset.NewForConfigOrDie(config3)
+
+	_, _ = client1.CoreV1().Nodes().List(ctx, metav1.ListOptions{})
+	_, _ = client2.CoreV1().Namespaces().List(ctx, metav1.ListOptions{})
+	_, _ = client3.CoreV1().PersistentVolumes().List(ctx, metav1.ListOptions{})
+
+	rt1 := client1.RESTClient().(*rest.RESTClient).Client.Transport
+	rt2 := client2.RESTClient().(*rest.RESTClient).Client.Transport
+	rt3 := client3.RESTClient().(*rest.RESTClient).Client.Transport
+
+	tlsConfig1, err := utilnet.TLSClientConfig(rt1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	tlsConfig2, err := utilnet.TLSClientConfig(rt2)
+	if err != nil {
+		t.Fatal(err)
+	}
+	tlsConfig3, err := utilnet.TLSClientConfig(rt3)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if tlsConfig1 == nil || tlsConfig2 == nil || tlsConfig3 == nil {
+		t.Fatal("expected non-nil TLS configs")
+	}
+
+	if tlsConfig1 != tlsConfig2 {
+		t.Fatal("expected the same TLS config for matching exec config via rest config")
+	}
+
+	if tlsConfig1 == tlsConfig3 {
+		t.Fatal("expected different TLS config for non-matching exec config via rest config")
+	}
+}

rest/request.go

@@ -82,6 +82,12 @@ func (r *RequestConstructionError) Error() string {
 
 var noBackoff = &NoBackoff{}
 
+type requestRetryFunc func(maxRetries int) WithRetry
+
+func defaultRequestRetryFn(maxRetries int) WithRetry {
+	return &withRetry{maxRetries: maxRetries}
+}
+
 // Request allows for building up a request to a server in a chained fashion.
 // Any errors are stored until the end of your call, so you only have to
 // check once.
@@ -93,6 +99,7 @@ type Request struct {
 	rateLimiter flowcontrol.RateLimiter
 	backoff     BackoffManager
 	timeout     time.Duration
+	maxRetries  int
 
 	// generic components accessible via method setters
 	verb       string
@@ -109,9 +116,10 @@ type Request struct {
 	subresource  string
 
 	// output
-	err   error
-	body  io.Reader
-	retry WithRetry
+	err  error
+	body io.Reader
+
+	retryFn requestRetryFunc
 }
 
 // NewRequest creates a new request helper object for accessing runtime.Objects on a server.
@@ -142,7 +150,8 @@ func NewRequest(c *RESTClient) *Request {
 		backoff:        backoff,
 		timeout:        timeout,
 		pathPrefix:     pathPrefix,
-		retry:          &withRetry{maxRetries: 10},
+		maxRetries:     10,
+		retryFn:        defaultRequestRetryFn,
 		warningHandler: c.warningHandler,
 	}
 
@@ -408,7 +417,10 @@ func (r *Request) Timeout(d time.Duration) *Request {
 // function is specifically called with a different value.
 // A zero maxRetries prevent it from doing retires and return an error immediately.
 func (r *Request) MaxRetries(maxRetries int) *Request {
-	r.retry.SetMaxRetries(maxRetries)
+	if maxRetries < 0 {
+		maxRetries = 0
+	}
+	r.maxRetries = maxRetries
 	return r
 }
 
@@ -688,8 +700,10 @@ func (r *Request) Watch(ctx context.Context) (watch.Interface, error) {
 		}
 		return false
 	}
+
 	var retryAfter *RetryAfter
 	url := r.URL().String()
+	withRetry := r.retryFn(r.maxRetries)
 	for {
 		req, err := r.newHTTPRequest(ctx)
 		if err != nil {
@@ -724,9 +738,9 @@ func (r *Request) Watch(ctx context.Context) (watch.Interface, error) {
 			defer readAndCloseResponseBody(resp)
 
 			var retry bool
-			retryAfter, retry = r.retry.NextRetry(req, resp, err, isErrRetryableFunc)
+			retryAfter, retry = withRetry.NextRetry(req, resp, err, isErrRetryableFunc)
 			if retry {
-				err := r.retry.BeforeNextRetry(ctx, r.backoff, retryAfter, url, r.body)
+				err := withRetry.BeforeNextRetry(ctx, r.backoff, retryAfter, url, r.body)
 				if err == nil {
 					return false, nil
 				}
@@ -817,6 +831,7 @@ func (r *Request) Stream(ctx context.Context) (io.ReadCloser, error) {
 	}
 
 	var retryAfter *RetryAfter
+	withRetry := r.retryFn(r.maxRetries)
 	url := r.URL().String()
 	for {
 		req, err := r.newHTTPRequest(ctx)
@@ -862,9 +877,9 @@ func (r *Request) Stream(ctx context.Context) (io.ReadCloser, error) {
 				defer resp.Body.Close()
 
 				var retry bool
-				retryAfter, retry = r.retry.NextRetry(req, resp, err, neverRetryError)
+				retryAfter, retry = withRetry.NextRetry(req, resp, err, neverRetryError)
 				if retry {
-					err := r.retry.BeforeNextRetry(ctx, r.backoff, retryAfter, url, r.body)
+					err := withRetry.BeforeNextRetry(ctx, r.backoff, retryAfter, url, r.body)
 					if err == nil {
 						return false, nil
 					}
@@ -961,6 +976,7 @@ func (r *Request) request(ctx context.Context, fn func(*http.Request, *http.Resp
 
 	// Right now we make about ten retry attempts if we get a Retry-After response.
 	var retryAfter *RetryAfter
+	withRetry := r.retryFn(r.maxRetries)
 	for {
 		req, err := r.newHTTPRequest(ctx)
 		if err != nil {
@@ -997,7 +1013,7 @@ func (r *Request) request(ctx context.Context, fn func(*http.Request, *http.Resp
 			}
 
 			var retry bool
-			retryAfter, retry = r.retry.NextRetry(req, resp, err, func(req *http.Request, err error) bool {
+			retryAfter, retry = withRetry.NextRetry(req, resp, err, func(req *http.Request, err error) bool {
 				// "Connection reset by peer" or "apiserver is shutting down" are usually a transient errors.
 				// Thus in case of "GET" operations, we simply retry it.
 				// We are not automatically retrying "write" operations, as they are not idempotent.
@@ -1011,7 +1027,7 @@ func (r *Request) request(ctx context.Context, fn func(*http.Request, *http.Resp
 				return false
 			})
 			if retry {
-				err := r.retry.BeforeNextRetry(ctx, r.backoff, retryAfter, req.URL.String(), r.body)
+				err := withRetry.BeforeNextRetry(ctx, r.backoff, retryAfter, req.URL.String(), r.body)
 				if err == nil {
 					return false
 				}

rest/request_test.go

@@ -32,6 +32,7 @@ import (
 	"reflect"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"syscall"
 	"testing"
 	"time"
@@ -1194,7 +1195,8 @@ func TestRequestWatch(t *testing.T) {
 				c.Client = client
 			}
 			testCase.Request.backoff = &noSleepBackOff{}
-			testCase.Request.retry = &withRetry{maxRetries: testCase.maxRetries}
+			testCase.Request.maxRetries = testCase.maxRetries
+			testCase.Request.retryFn = defaultRequestRetryFn
 
 			watch, err := testCase.Request.Watch(context.Background())
 
@@ -1407,7 +1409,8 @@ func TestRequestStream(t *testing.T) {
 				c.Client = client
 			}
 			testCase.Request.backoff = &noSleepBackOff{}
-			testCase.Request.retry = &withRetry{maxRetries: testCase.maxRetries}
+			testCase.Request.maxRetries = testCase.maxRetries
+			testCase.Request.retryFn = defaultRequestRetryFn
 
 			body, err := testCase.Request.Stream(context.Background())
 
@@ -1462,7 +1465,7 @@ func TestRequestDo(t *testing.T) {
 	}
 	for i, testCase := range testCases {
 		testCase.Request.backoff = &NoBackoff{}
-		testCase.Request.retry = &withRetry{}
+		testCase.Request.retryFn = defaultRequestRetryFn
 		body, err := testCase.Request.Do(context.Background()).Raw()
 		hasErr := err != nil
 		if hasErr != testCase.Err {
@@ -1625,8 +1628,9 @@ func TestConnectionResetByPeerIsRetried(t *testing.T) {
 				return nil, &net.OpError{Err: syscall.ECONNRESET}
 			}),
 		},
-		backoff: backoff,
-		retry:   &withRetry{maxRetries: 10},
+		backoff:    backoff,
+		maxRetries: 10,
+		retryFn:    defaultRequestRetryFn,
 	}
 	// We expect two retries of "connection reset by peer" and the success.
 	_, err := req.Do(context.Background()).Raw()
@@ -2699,8 +2703,9 @@ func TestRequestWithRetry(t *testing.T) {
 				c: &RESTClient{
 					Client: client,
 				},
-				backoff: &noSleepBackOff{},
-				retry:   &withRetry{maxRetries: 1},
+				backoff:    &noSleepBackOff{},
+				maxRetries: 1,
+				retryFn:    defaultRequestRetryFn,
 			}
 
 			var transformFuncInvoked int
@@ -2890,8 +2895,9 @@ func testRequestWithRetry(t *testing.T, key string, doFunc func(ctx context.Cont
 					content: defaultContentConfig(),
 					Client:  client,
 				},
-				backoff: &noSleepBackOff{},
-				retry:   &withRetry{maxRetries: test.maxRetries},
+				backoff:    &noSleepBackOff{},
+				maxRetries: test.maxRetries,
+				retryFn:    defaultRequestRetryFn,
 			}
 
 			doFunc(context.Background(), req)
@@ -2995,7 +3001,7 @@ func TestHTTP1DoNotReuseRequestAfterTimeout(t *testing.T) {
 			config := &Config{
 				Host:      ts.URL,
 				Transport: utilnet.SetTransportDefaults(transport),
-				Timeout:   100 * time.Millisecond,
+				Timeout:   1 * time.Second,
 				// These fields are required to create a REST client.
 				ContentConfig: ContentConfig{
 					GroupVersion:         &schema.GroupVersion{},
@@ -3093,3 +3099,50 @@ func TestTransportConcurrency(t *testing.T) {
 		})
 	}
 }
+
+func TestRequestConcurrencyWithRetry(t *testing.T) {
+	var attempts int32
+	client := clientForFunc(func(req *http.Request) (*http.Response, error) {
+		defer func() {
+			atomic.AddInt32(&attempts, 1)
+		}()
+
+		// always send a retry-after response
+		return &http.Response{
+			StatusCode: http.StatusInternalServerError,
+			Header:     http.Header{"Retry-After": []string{"1"}},
+		}, nil
+	})
+
+	req := &Request{
+		verb: "POST",
+		c: &RESTClient{
+			content: defaultContentConfig(),
+			Client:  client,
+		},
+		backoff:    &noSleepBackOff{},
+		maxRetries: 9, // 10 attempts in total, including the first
+		retryFn:    defaultRequestRetryFn,
+	}
+
+	concurrency := 20
+	wg := sync.WaitGroup{}
+	wg.Add(concurrency)
+	startCh := make(chan struct{})
+	for i := 0; i < concurrency; i++ {
+		go func() {
+			defer wg.Done()
+			<-startCh
+			req.Do(context.Background())
+		}()
+	}
+
+	close(startCh)
+	wg.Wait()
+
+	// we expect (concurrency*req.maxRetries+1) attempts to be recorded
+	expected := concurrency * (req.maxRetries + 1)
+	if atomic.LoadInt32(&attempts) != int32(expected) {
+		t.Errorf("Expected attempts: %d, but got: %d", expected, attempts)
+	}
+}

tools/cache/thread_safe_store.go

@@ -284,18 +284,15 @@ func (c *threadSafeMap) updateIndices(oldObj interface{}, newObj interface{}, ke
 			c.indices[name] = index
 		}
 
+		if len(indexValues) == 1 && len(oldIndexValues) == 1 && indexValues[0] == oldIndexValues[0] {
+			// We optimize for the most common case where indexFunc returns a single value which has not been changed
+			continue
+		}
+
 		for _, value := range oldIndexValues {
-			// We optimize for the most common case where index returns a single value.
-			if len(indexValues) == 1 && value == indexValues[0] {
-				continue
-			}
 			c.deleteKeyFromIndex(key, value, index)
 		}
 		for _, value := range indexValues {
-			// We optimize for the most common case where index returns a single value.
-			if len(oldIndexValues) == 1 && value == oldIndexValues[0] {
-				continue
-			}
 			c.addKeyToIndex(key, value, index)
 		}
 	}

tools/cache/thread_safe_store_test.go

@@ -18,7 +18,11 @@ package cache
 
 import (
 	"fmt"
+	"strings"
 	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/stretchr/testify/assert"
 )
 
 func TestThreadSafeStoreDeleteRemovesEmptySetsFromIndex(t *testing.T) {
@@ -92,6 +96,75 @@ func TestThreadSafeStoreAddKeepsNonEmptySetPostDeleteFromIndex(t *testing.T) {
 	}
 }
 
+func TestThreadSafeStoreIndexingFunctionsWithMultipleValues(t *testing.T) {
+	testIndexer := "testIndexer"
+
+	indexers := Indexers{
+		testIndexer: func(obj interface{}) ([]string, error) {
+			return strings.Split(obj.(string), ","), nil
+		},
+	}
+
+	indices := Indices{}
+	store := NewThreadSafeStore(indexers, indices).(*threadSafeMap)
+
+	store.Add("key1", "foo")
+	store.Add("key2", "bar")
+
+	assert := assert.New(t)
+
+	compare := func(key string, expected []string) error {
+		values := store.indices[testIndexer][key].List()
+		if cmp.Equal(values, expected) {
+			return nil
+		}
+		return fmt.Errorf("unexpected index for key %s, diff=%s", key, cmp.Diff(values, expected))
+	}
+
+	assert.NoError(compare("foo", []string{"key1"}))
+	assert.NoError(compare("bar", []string{"key2"}))
+
+	store.Update("key2", "foo,bar")
+
+	assert.NoError(compare("foo", []string{"key1", "key2"}))
+	assert.NoError(compare("bar", []string{"key2"}))
+
+	store.Update("key1", "foo,bar")
+
+	assert.NoError(compare("foo", []string{"key1", "key2"}))
+	assert.NoError(compare("bar", []string{"key1", "key2"}))
+
+	store.Add("key3", "foo,bar,baz")
+
+	assert.NoError(compare("foo", []string{"key1", "key2", "key3"}))
+	assert.NoError(compare("bar", []string{"key1", "key2", "key3"}))
+	assert.NoError(compare("baz", []string{"key3"}))
+
+	store.Update("key1", "foo")
+
+	assert.NoError(compare("foo", []string{"key1", "key2", "key3"}))
+	assert.NoError(compare("bar", []string{"key2", "key3"}))
+	assert.NoError(compare("baz", []string{"key3"}))
+
+	store.Update("key2", "bar")
+
+	assert.NoError(compare("foo", []string{"key1", "key3"}))
+	assert.NoError(compare("bar", []string{"key2", "key3"}))
+	assert.NoError(compare("baz", []string{"key3"}))
+
+	store.Delete("key1")
+
+	assert.NoError(compare("foo", []string{"key3"}))
+	assert.NoError(compare("bar", []string{"key2", "key3"}))
+	assert.NoError(compare("baz", []string{"key3"}))
+
+	store.Delete("key3")
+
+	assert.NoError(compare("foo", []string{}))
+	assert.NoError(compare("bar", []string{"key2"}))
+	assert.NoError(compare("baz", []string{}))
+}
+
 func BenchmarkIndexer(b *testing.B) {
 	testIndexer := "testIndexer"
 

tools/clientcmd/auth_loaders.go

@@ -51,10 +51,10 @@ func (a *PromptingAuthLoader) LoadAuth(path string) (*clientauth.Info, error) {
 	// Prompt for user/pass and write a file if none exists.
 	if _, err := os.Stat(path); os.IsNotExist(err) {
 		authPtr, err := a.Prompt()
-		auth := *authPtr
 		if err != nil {
 			return nil, err
 		}
+		auth := *authPtr
 		data, err := json.Marshal(auth)
 		if err != nil {
 			return &auth, err

tools/pager/pager.go

@@ -78,6 +78,7 @@ func (p *ListPager) List(ctx context.Context, options metav1.ListOptions) (runti
 		options.Limit = p.PageSize
 	}
 	requestedResourceVersion := options.ResourceVersion
+	requestedResourceVersionMatch := options.ResourceVersionMatch
 	var list *metainternalversion.List
 	paginatedResult := false
 
@@ -102,6 +103,7 @@ func (p *ListPager) List(ctx context.Context, options metav1.ListOptions) (runti
 			options.Limit = 0
 			options.Continue = ""
 			options.ResourceVersion = requestedResourceVersion
+			options.ResourceVersionMatch = requestedResourceVersionMatch
 			result, err := p.PageFn(ctx, options)
 			return result, paginatedResult, err
 		}
@@ -135,10 +137,11 @@ func (p *ListPager) List(ctx context.Context, options metav1.ListOptions) (runti
 
 		// set the next loop up
 		options.Continue = m.GetContinue()
-		// Clear the ResourceVersion on the subsequent List calls to avoid the
+		// Clear the ResourceVersion(Match) on the subsequent List calls to avoid the
 		// `specifying resource version is not allowed when using continue` error.
 		// See https://github.com/kubernetes/kubernetes/issues/85221#issuecomment-553748143.
 		options.ResourceVersion = ""
+		options.ResourceVersionMatch = ""
 		// At this point, result is already paginated.
 		paginatedResult = true
 	}

tools/pager/pager_test.go

@@ -76,6 +76,10 @@ func (p *testPager) PagedList(ctx context.Context, options metav1.ListOptions) (
 		p.t.Errorf("invariant violated, specifying resource version (%s) is not allowed when using continue (%s).", options.ResourceVersion, options.Continue)
 		return nil, fmt.Errorf("invariant violated")
 	}
+	if options.Continue != "" && options.ResourceVersionMatch != "" {
+		p.t.Errorf("invariant violated, specifying resource version match type (%s) is not allowed when using continue (%s).", options.ResourceVersionMatch, options.Continue)
+		return nil, fmt.Errorf("invariant violated")
+	}
 	var list metainternalversion.List
 	total := options.Limit
 	if total == 0 {
@@ -201,6 +205,13 @@ func TestListPager_List(t *testing.T) {
 			want:      list(11, "rv:20"),
 			wantPaged: true,
 		},
+		{
+			name:      "two pages with resourceVersion and resourceVersionMatch",
+			fields:    fields{PageSize: 10, PageFn: (&testPager{t: t, expectPage: 10, remaining: 11, rv: "rv:20"}).PagedList},
+			args:      args{options: metav1.ListOptions{ResourceVersion: "rv:10", ResourceVersionMatch: metav1.ResourceVersionMatchNotOlderThan}},
+			want:      list(11, "rv:20"),
+			wantPaged: true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

transport/cache.go

@@ -17,6 +17,7 @@ limitations under the License.
 package transport
 
 import (
+	"context"
 	"fmt"
 	"net"
 	"net/http"
@@ -50,6 +51,9 @@ type tlsCacheKey struct {
 	serverName         string
 	nextProtos         string
 	disableCompression bool
+	// these functions are wrapped to allow them to be used as map keys
+	getCert *GetCertHolder
+	dial    *DialHolder
 }
 
 func (t tlsCacheKey) String() string {
@@ -57,7 +61,8 @@ func (t tlsCacheKey) String() string {
 	if len(t.keyData) > 0 {
 		keyText = "<redacted>"
 	}
-	return fmt.Sprintf("insecure:%v, caData:%#v, certData:%#v, keyData:%s, serverName:%s, disableCompression:%t", t.insecure, t.caData, t.certData, keyText, t.serverName, t.disableCompression)
+	return fmt.Sprintf("insecure:%v, caData:%#v, certData:%#v, keyData:%s, serverName:%s, disableCompression:%t, getCert:%p, dial:%p",
+		t.insecure, t.caData, t.certData, keyText, t.serverName, t.disableCompression, t.getCert, t.dial)
 }
 
 func (c *tlsTransportCache) get(config *Config) (http.RoundTripper, error) {
@@ -87,8 +92,10 @@ func (c *tlsTransportCache) get(config *Config) (http.RoundTripper, error) {
 		return http.DefaultTransport, nil
 	}
 
-	dial := config.Dial
-	if dial == nil {
+	var dial func(ctx context.Context, network, address string) (net.Conn, error)
+	if config.Dial != nil {
+		dial = config.Dial
+	} else {
 		dial = (&net.Dialer{
 			Timeout:   30 * time.Second,
 			KeepAlive: 30 * time.Second,
@@ -133,10 +140,18 @@ func tlsConfigKey(c *Config) (tlsCacheKey, bool, error) {
 		return tlsCacheKey{}, false, err
 	}
 
-	if c.TLS.GetCert != nil || c.Dial != nil || c.Proxy != nil {
+	if c.Proxy != nil {
 		// cannot determine equality for functions
 		return tlsCacheKey{}, false, nil
 	}
+	if c.Dial != nil && c.DialHolder == nil {
+		// cannot determine equality for dial function that doesn't have non-nil DialHolder set as well
+		return tlsCacheKey{}, false, nil
+	}
+	if c.TLS.GetCert != nil && c.TLS.GetCertHolder == nil {
+		// cannot determine equality for getCert function that doesn't have non-nil GetCertHolder set as well
+		return tlsCacheKey{}, false, nil
+	}
 
 	k := tlsCacheKey{
 		insecure:           c.TLS.Insecure,
@@ -144,6 +159,8 @@ func tlsConfigKey(c *Config) (tlsCacheKey, bool, error) {
 		serverName:         c.TLS.ServerName,
 		nextProtos:         strings.Join(c.TLS.NextProtos, ","),
 		disableCompression: c.DisableCompression,
+		getCert:            c.TLS.GetCertHolder,
+		dial:               c.DialHolder,
 	}
 
 	if c.TLS.ReloadTLSFiles {

transport/cache_test.go

@@ -21,6 +21,7 @@ import (
 	"crypto/tls"
 	"net"
 	"net/http"
+	"net/url"
 	"testing"
 )
 
@@ -58,16 +59,24 @@ func TestTLSConfigKey(t *testing.T) {
 				t.Errorf("Expected identical cache keys for %q and %q, got:\n\t%s\n\t%s", nameA, nameB, keyA, keyB)
 				continue
 			}
+			if keyA != (tlsCacheKey{}) {
+				t.Errorf("Expected empty cache keys for %q and %q, got:\n\t%s\n\t%s", nameA, nameB, keyA, keyB)
+				continue
+			}
 		}
 	}
 
 	// Make sure config fields that affect the tls config affect the cache key
 	dialer := net.Dialer{}
 	getCert := func() (*tls.Certificate, error) { return nil, nil }
+	getCertHolder := &GetCertHolder{GetCert: getCert}
 	uniqueConfigurations := map[string]*Config{
+		"proxy":    {Proxy: func(request *http.Request) (*url.URL, error) { return nil, nil }},
 		"no tls":   {},
 		"dialer":   {Dial: dialer.DialContext},
 		"dialer2":  {Dial: func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil }},
+		"dialer3":  {Dial: dialer.DialContext, DialHolder: &DialHolder{Dial: dialer.DialContext}},
+		"dialer4":  {Dial: func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil }, DialHolder: &DialHolder{Dial: func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil }}},
 		"insecure": {TLS: TLSConfig{Insecure: true}},
 		"cadata 1": {TLS: TLSConfig{CAData: []byte{1}}},
 		"cadata 2": {TLS: TLSConfig{CAData: []byte{2}}},
@@ -128,6 +137,13 @@ func TestTLSConfigKey(t *testing.T) {
 				GetCert: func() (*tls.Certificate, error) { return nil, nil },
 			},
 		},
+		"getCert3": {
+			TLS: TLSConfig{
+				KeyData:       []byte{1},
+				GetCert:       getCert,
+				GetCertHolder: getCertHolder,
+			},
+		},
 		"getCert1, key 2": {
 			TLS: TLSConfig{
 				KeyData: []byte{2},

transport/config.go

@@ -68,7 +68,11 @@ type Config struct {
 	WrapTransport WrapperFunc
 
 	// Dial specifies the dial function for creating unencrypted TCP connections.
+	// If specified, this transport will be non-cacheable unless DialHolder is also set.
 	Dial func(ctx context.Context, network, address string) (net.Conn, error)
+	// DialHolder can be populated to make transport configs cacheable.
+	// If specified, DialHolder.Dial must be equal to Dial.
+	DialHolder *DialHolder
 
 	// Proxy is the proxy func to be used for all requests made by this
 	// transport. If Proxy is nil, http.ProxyFromEnvironment is used. If Proxy
@@ -78,6 +82,11 @@ type Config struct {
 	Proxy func(*http.Request) (*url.URL, error)
 }
 
+// DialHolder is used to make the wrapped function comparable so that it can be used as a map key.
+type DialHolder struct {
+	Dial func(ctx context.Context, network, address string) (net.Conn, error)
+}
+
 // ImpersonationConfig has all the available impersonation options
 type ImpersonationConfig struct {
 	// UserName matches user.Info.GetName()
@@ -143,5 +152,15 @@ type TLSConfig struct {
 	// To use only http/1.1, set to ["http/1.1"].
 	NextProtos []string
 
-	GetCert func() (*tls.Certificate, error) // Callback that returns a TLS client certificate. CertData, CertFile, KeyData and KeyFile supercede this field.
+	// Callback that returns a TLS client certificate. CertData, CertFile, KeyData and KeyFile supercede this field.
+	// If specified, this transport is non-cacheable unless CertHolder is populated.
+	GetCert func() (*tls.Certificate, error)
+	// CertHolder can be populated to make transport configs that set GetCert cacheable.
+	// If set, CertHolder.GetCert must be equal to GetCert.
+	GetCertHolder *GetCertHolder
+}
+
+// GetCertHolder is used to make the wrapped function comparable so that it can be used as a map key.
+type GetCertHolder struct {
+	GetCert func() (*tls.Certificate, error)
 }

transport/transport.go

@@ -24,6 +24,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net/http"
+	"reflect"
 	"sync"
 	"time"
 
@@ -39,6 +40,10 @@ func New(config *Config) (http.RoundTripper, error) {
 		return nil, fmt.Errorf("using a custom transport with TLS certificate options or the insecure flag is not allowed")
 	}
 
+	if !isValidHolders(config) {
+		return nil, fmt.Errorf("misconfigured holder for dialer or cert callback")
+	}
+
 	var (
 		rt  http.RoundTripper
 		err error
@@ -56,6 +61,26 @@ func New(config *Config) (http.RoundTripper, error) {
 	return HTTPWrappersForConfig(config, rt)
 }
 
+func isValidHolders(config *Config) bool {
+	if config.TLS.GetCertHolder != nil {
+		if config.TLS.GetCertHolder.GetCert == nil ||
+			config.TLS.GetCert == nil ||
+			reflect.ValueOf(config.TLS.GetCertHolder.GetCert).Pointer() != reflect.ValueOf(config.TLS.GetCert).Pointer() {
+			return false
+		}
+	}
+
+	if config.DialHolder != nil {
+		if config.DialHolder.Dial == nil ||
+			config.Dial == nil ||
+			reflect.ValueOf(config.DialHolder.Dial).Pointer() != reflect.ValueOf(config.Dial).Pointer() {
+			return false
+		}
+	}
+
+	return true
+}
+
 // TLSConfigFor returns a tls.Config that will provide the transport level security defined
 // by the provided Config. Will return nil if no transport level security is requested.
 func TLSConfigFor(c *Config) (*tls.Config, error) {

transport/transport_test.go

@@ -21,6 +21,7 @@ import (
 	"crypto/tls"
 	"errors"
 	"fmt"
+	"net"
 	"net/http"
 	"testing"
 )
@@ -94,6 +95,13 @@ stR0Yiw0buV6DL/moUO0HIM9Bjh96HJp+LxiIS6UCdIhMPp5HoQa
 )
 
 func TestNew(t *testing.T) {
+	globalGetCert := &GetCertHolder{
+		GetCert: func() (*tls.Certificate, error) { return nil, nil },
+	}
+	globalDial := &DialHolder{
+		Dial: func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil },
+	}
+
 	testCases := map[string]struct {
 		Config       *Config
 		Err          bool
@@ -255,6 +263,144 @@ func TestNew(t *testing.T) {
 				},
 			},
 		},
+		"nil holders and nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       nil,
+					GetCertHolder: nil,
+				},
+				Dial:       nil,
+				DialHolder: nil,
+			},
+			Err:          false,
+			TLS:          false,
+			TLSCert:      false,
+			TLSErr:       false,
+			Default:      true,
+			Insecure:     false,
+			DefaultRoots: false,
+		},
+		"nil holders and non-nil regular get cert": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       func() (*tls.Certificate, error) { return nil, nil },
+					GetCertHolder: nil,
+				},
+				Dial:       nil,
+				DialHolder: nil,
+			},
+			Err:          false,
+			TLS:          true,
+			TLSCert:      true,
+			TLSErr:       false,
+			Default:      false,
+			Insecure:     false,
+			DefaultRoots: true,
+		},
+		"nil holders and non-nil regular dial": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       nil,
+					GetCertHolder: nil,
+				},
+				Dial:       func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil },
+				DialHolder: nil,
+			},
+			Err:          false,
+			TLS:          true,
+			TLSCert:      false,
+			TLSErr:       false,
+			Default:      false,
+			Insecure:     false,
+			DefaultRoots: true,
+		},
+		"non-nil dial holder and nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       nil,
+					GetCertHolder: nil,
+				},
+				Dial:       nil,
+				DialHolder: &DialHolder{},
+			},
+			Err: true,
+		},
+		"non-nil cert holder and nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       nil,
+					GetCertHolder: &GetCertHolder{},
+				},
+				Dial:       nil,
+				DialHolder: nil,
+			},
+			Err: true,
+		},
+		"non-nil dial holder and non-nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       nil,
+					GetCertHolder: nil,
+				},
+				Dial:       func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil },
+				DialHolder: &DialHolder{},
+			},
+			Err: true,
+		},
+		"non-nil cert holder and non-nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       func() (*tls.Certificate, error) { return nil, nil },
+					GetCertHolder: &GetCertHolder{},
+				},
+				Dial:       nil,
+				DialHolder: nil,
+			},
+			Err: true,
+		},
+		"non-nil dial holder+internal and non-nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       nil,
+					GetCertHolder: nil,
+				},
+				Dial: func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil },
+				DialHolder: &DialHolder{
+					Dial: func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil },
+				},
+			},
+			Err: true,
+		},
+		"non-nil cert holder+internal and non-nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert: func() (*tls.Certificate, error) { return nil, nil },
+					GetCertHolder: &GetCertHolder{
+						GetCert: func() (*tls.Certificate, error) { return nil, nil },
+					},
+				},
+				Dial:       nil,
+				DialHolder: nil,
+			},
+			Err: true,
+		},
+		"non-nil holders+internal and non-nil regular with correct address": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       globalGetCert.GetCert,
+					GetCertHolder: globalGetCert,
+				},
+				Dial:       globalDial.Dial,
+				DialHolder: globalDial,
+			},
+			Err:          false,
+			TLS:          true,
+			TLSCert:      true,
+			TLSErr:       false,
+			Default:      false,
+			Insecure:     false,
+			DefaultRoots: true,
+		},
 	}
 	for k, testCase := range testCases {
 		t.Run(k, func(t *testing.T) {