kubeadm: Utilize transport defaults from API machinery for http calls

cmd/kubeadm/app/discovery/https/BUILD

@@ -11,6 +11,7 @@ go_library(
     importpath = "k8s.io/kubernetes/cmd/kubeadm/app/discovery/https",
     deps = [
         "//cmd/kubeadm/app/discovery/file:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/util/net:go_default_library",
         "//vendor/k8s.io/client-go/tools/clientcmd:go_default_library",
         "//vendor/k8s.io/client-go/tools/clientcmd/api:go_default_library",
     ],

cmd/kubeadm/app/discovery/https/https.go

@@ -20,6 +20,7 @@ import (
 	"io/ioutil"
 	"net/http"
 
+	netutil "k8s.io/apimachinery/pkg/util/net"
 	"k8s.io/client-go/tools/clientcmd"
 	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
 	"k8s.io/kubernetes/cmd/kubeadm/app/discovery/file"
@@ -29,7 +30,8 @@ import (
 // securely to the API Server using the provided CA cert and
 // optionally refreshes the cluster-info information from the cluster-info ConfigMap
 func RetrieveValidatedClusterInfo(httpsURL string) (*clientcmdapi.Cluster, error) {
-	response, err := http.Get(httpsURL)
+	client := &http.Client{Transport: netutil.SetOldTransportDefaults(&http.Transport{})}
+	response, err := client.Get(httpsURL)
 	if err != nil {
 		return nil, err
 	}

cmd/kubeadm/app/preflight/checks.go

@@ -332,7 +332,7 @@ func (hst HTTPProxyCheck) Check() (warnings, errors []error) {
 		return nil, []error{err}
 	}
 
-	proxy, err := http.DefaultTransport.(*http.Transport).Proxy(req)
+	proxy, err := netutil.SetOldTransportDefaults(&http.Transport{}).Proxy(req)
 	if err != nil {
 		return nil, []error{err}
 	}
@@ -670,15 +670,15 @@ func (evc ExternalEtcdVersionCheck) configCertAndKey(config *tls.Config) (*tls.C
 
 func (evc ExternalEtcdVersionCheck) getHTTPClient(config *tls.Config) *http.Client {
 	if config != nil {
-		transport := &http.Transport{
+		transport := netutil.SetOldTransportDefaults(&http.Transport{
 			TLSClientConfig: config,
-		}
+		})
 		return &http.Client{
 			Transport: transport,
 			Timeout:   externalEtcdRequestTimeout,
 		}
 	}
-	return &http.Client{Timeout: externalEtcdRequestTimeout}
+	return &http.Client{Timeout: externalEtcdRequestTimeout, Transport: netutil.SetOldTransportDefaults(&http.Transport{})}
 }
 
 func getEtcdVersionResponse(client *http.Client, url string, target interface{}) error {

cmd/kubeadm/app/util/BUILD

@@ -23,6 +23,7 @@ go_library(
         "//vendor/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/errors:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/util/net:go_default_library",
         "//vendor/k8s.io/client-go/kubernetes/scheme:go_default_library",
     ],
 )

cmd/kubeadm/app/util/apiclient/BUILD

@@ -28,6 +28,7 @@ go_library(
         "//vendor/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/intstr:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/util/net:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/wait:go_default_library",
         "//vendor/k8s.io/client-go/dynamic:go_default_library",
         "//vendor/k8s.io/client-go/kubernetes:go_default_library",

cmd/kubeadm/app/util/apiclient/wait.go

@@ -27,6 +27,7 @@ import (
 	"k8s.io/api/core/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	netutil "k8s.io/apimachinery/pkg/util/net"
 	"k8s.io/apimachinery/pkg/util/wait"
 	clientset "k8s.io/client-go/kubernetes"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
@@ -130,7 +131,8 @@ func (w *KubeWaiter) WaitForPodToDisappear(podName string) error {
 func (w *KubeWaiter) WaitForHealthyKubelet(initalTimeout time.Duration, healthzEndpoint string) error {
 	time.Sleep(initalTimeout)
 	return TryRunCommand(func() error {
-		resp, err := http.Get(healthzEndpoint)
+		client := &http.Client{Transport: netutil.SetOldTransportDefaults(&http.Transport{})}
+		resp, err := client.Get(healthzEndpoint)
 		if err != nil {
 			fmt.Printf("[kubelet-check] It seems like the kubelet isn't running or healthy.\n")
 			fmt.Printf("[kubelet-check] The HTTP call equal to 'curl -sSL %s' failed with error: %v.\n", healthzEndpoint, err)

cmd/kubeadm/app/util/version.go

@@ -22,6 +22,8 @@ import (
 	"net/http"
 	"regexp"
 	"strings"
+
+	netutil "k8s.io/apimachinery/pkg/util/net"
 )
 
 var (
@@ -131,7 +133,8 @@ func splitVersion(version string) (string, string, error) {
 
 // Internal helper: return content of URL
 func fetchFromURL(url string) (string, error) {
-	resp, err := http.Get(url)
+	client := &http.Client{Transport: netutil.SetOldTransportDefaults(&http.Transport{})}
+	resp, err := client.Get(url)
 	if err != nil {
 		return "", fmt.Errorf("unable to get URL %q: %s", url, err.Error())
 	}