kubeadm: added HTTPS discovery.

cmd/kubeadm/app/discovery/BUILD

@@ -20,6 +20,7 @@ go_library(
         "//cmd/kubeadm/app/discovery/file:go_default_library",
         "//cmd/kubeadm/app/discovery/https:go_default_library",
         "//cmd/kubeadm/app/discovery/token:go_default_library",
+        "//pkg/client/unversioned/clientcmd:go_default_library",
         "//pkg/client/unversioned/clientcmd/api:go_default_library",
         "//vendor:github.com/spf13/pflag",
     ],

cmd/kubeadm/app/discovery/discovery.go

@@ -18,8 +18,11 @@ package discovery
 
 import (
 	"fmt"
+	"io/ioutil"
+	"net/http"
 
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
+	"k8s.io/kubernetes/pkg/client/unversioned/clientcmd"
 	clientcmdapi "k8s.io/kubernetes/pkg/client/unversioned/clientcmd/api"
 )
 
@@ -28,6 +31,8 @@ func For(d kubeadmapi.Discovery) (*clientcmdapi.Config, error) {
 	switch {
 	case d.File != nil:
 		return runFileDiscovery(d.File)
+	case d.HTTPS != nil:
+		return runHTTPSDiscovery(d.HTTPS)
 	default:
 		return nil, fmt.Errorf("Couldn't find a valid discovery configuration. Please provide one.")
 	}
@@ -37,5 +42,20 @@ func For(d kubeadmapi.Discovery) (*clientcmdapi.Config, error) {
 func runFileDiscovery(fd *kubeadmapi.FileDiscovery) (*clientcmdapi.Config, error) {
 	return clientcmd.LoadFromFile(fd.Path)
 }
+
+// runHTTPSDiscovery executes HTTPS-based discovery.
+func runHTTPSDiscovery(hd *kubeadmapi.HTTPSDiscovery) (*clientcmdapi.Config, error) {
+	response, err := http.Get(hd.URL)
+	if err != nil {
+		return nil, err
+	}
+	defer response.Body.Close()
+
+	kubeconfig, err := ioutil.ReadAll(response.Body)
+	if err != nil {
+		return nil, err
 	}
+
+	return clientcmd.Load(kubeconfig)
+}
 }