Merge pull request #69486 from fabriziopandini/kubeadm-stacked-etcd

cmd/kubeadm/app/cmd/join.go

@@ -30,7 +30,6 @@ import (
 	"github.com/renstrom/dedent"
 	"github.com/spf13/cobra"
 	flag "github.com/spf13/pflag"
-
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/util/wait"
 	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
@@ -44,6 +43,7 @@ import (
 	"k8s.io/kubernetes/cmd/kubeadm/app/features"
 	certsphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/certs"
 	controlplanephase "k8s.io/kubernetes/cmd/kubeadm/app/phases/controlplane"
+	etcdphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/etcd"
 	kubeconfigphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/kubeconfig"
 	kubeletphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/kubelet"
 	markmasterphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/markmaster"
@@ -74,7 +74,6 @@ var (
 
 		Please ensure that:
 		* The cluster has a stable controlPlaneEndpoint address.
-		* The cluster uses an external etcd.
 		* The certificates that must be shared among control plane instances are provided.
 
 		`)))
@@ -86,6 +85,7 @@ var (
 		* The Kubelet was informed of the new secure connection details.
 		* Master label and taint were applied to the new node.
 		* The kubernetes control plane instances scaled up.
+		{{.etcdMessage}}
 
 		To start administering your cluster from this node, you need to run the following as a regular user:
 
@@ -383,8 +383,15 @@ func (j *Join) Run(out io.Writer) error {
 		}
 
 		// outputs the join control plane done template and exits
+		etcdMessage := ""
+		// in case of local etcd
+		if initConfiguration.Etcd.External == nil {
+			etcdMessage = "* A new etcd member was added to the local/stacked etcd cluster."
+		}
+
 		ctx := map[string]string{
 			"KubeConfigPath": kubeadmconstants.GetAdminKubeConfigPath(),
+			"etcdMessage":    etcdMessage,
 		}
 		joinControPlaneDoneTemp.Execute(out, ctx)
 		return nil
@@ -421,11 +428,6 @@ func (j *Join) CheckIfReadyForAdditionalControlPlane(initConfiguration *kubeadma
 		return errors.New("unable to add a new control plane instance a cluster that doesn't have a stable controlPlaneEndpoint address")
 	}
 
-	// blocks if the cluster was created without an external etcd cluster
-	if initConfiguration.Etcd.External == nil {
-		return errors.New("unable to add a new control plane instance on a cluster that doesn't use an external etcd")
-	}
-
 	// blocks if control plane is self-hosted
 	if features.Enabled(initConfiguration.FeatureGates, features.SelfHosting) {
 		return errors.New("self-hosted clusters are deprecated and won't be supported by `kubeadm join --experimental-control-plane`")
@@ -465,6 +467,23 @@ func (j *Join) PrepareForHostingControlPlane(initConfiguration *kubeadmapi.InitC
 		return errors.Wrap(err, "error creating static pod manifest files for the control plane components")
 	}
 
+	// in case of local etcd
+	if initConfiguration.Etcd.External == nil {
+		// Checks that the etcd cluster is healthy
+		// NB. this check cannot be implemented before because it requires the admin.conf and all the certificates
+		//     for connecting to etcd already in place
+		kubeConfigFile := filepath.Join(kubeadmconstants.KubernetesDir, kubeadmconstants.AdminKubeConfigFileName)
+
+		client, err := kubeconfigutil.ClientSetFromFile(kubeConfigFile)
+		if err != nil {
+			return errors.Wrap(err, "couldn't create kubernetes client")
+		}
+
+		if err := etcdphase.CheckLocalEtcdClusterStatus(client, initConfiguration); err != nil {
+			return err
+		}
+	}
+
 	return nil
 }
 
@@ -559,6 +578,23 @@ func (j *Join) PostInstallControlPlane(initConfiguration *kubeadmapi.InitConfigu
 		return errors.Wrap(err, "couldn't create kubernetes client")
 	}
 
+	// in case of local etcd
+	if initConfiguration.Etcd.External == nil {
+		// Adds a new etcd instance; in order to do this the new etcd instance should be "announced" to
+		// the existing etcd members before being created.
+		// This operation must be executed after kubelet is already started in order to minimize the time
+		// between the new etcd member is announced and the start of the static pod running the new etcd member, because during
+		// this time frame etcd gets temporary not available (only when moving from 1 to 2 members in the etcd cluster).
+		// From https://coreos.com/etcd/docs/latest/v2/runtime-configuration.html
+		// "If you add a new member to a 1-node cluster, the cluster cannot make progress before the new member starts
+		// because it needs two members as majority to agree on the consensus. You will only see this behavior between the time
+		// etcdctl member add informs the cluster about the new member and the new member successfully establishing a connection to the existing one."
+		glog.V(1).Info("[join] adding etcd")
+		if err := etcdphase.CreateStackedEtcdStaticPodManifestFile(client, kubeadmconstants.GetStaticPodDirectory(), initConfiguration); err != nil {
+			return errors.Wrap(err, "error creating local etcd static pod manifest file")
+		}
+	}
+
 	glog.V(1).Info("[join] uploading currently used configuration to the cluster")
 	if err := uploadconfigphase.UploadConfiguration(initConfiguration, client); err != nil {
 		return errors.Wrap(err, "error uploading configuration: %v")

cmd/kubeadm/app/cmd/upgrade/apply.go

@@ -23,7 +23,6 @@ import (
 
 	"github.com/golang/glog"
 	"github.com/spf13/cobra"
-
 	"k8s.io/apimachinery/pkg/util/version"
 	clientset "k8s.io/client-go/kubernetes"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
@@ -303,7 +302,7 @@ func PerformStaticPodUpgrade(client clientset.Interface, waiter apiclient.Waiter
 	}
 
 	// The arguments oldEtcdClient and newEtdClient, are uninitialized because passing in the clients allow for mocking the client during testing
-	return upgrade.StaticPodControlPlane(waiter, pathManager, internalcfg, etcdUpgrade, nil, nil)
+	return upgrade.StaticPodControlPlane(client, waiter, pathManager, internalcfg, etcdUpgrade, nil, nil)
 }
 
 // DryRunStaticPodUpgrade fakes an upgrade of the control plane

cmd/kubeadm/app/cmd/upgrade/node.go

@@ -24,7 +24,6 @@ import (
 
 	"github.com/golang/glog"
 	"github.com/spf13/cobra"
-
 	"k8s.io/apimachinery/pkg/util/version"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
 	cmdutil "k8s.io/kubernetes/cmd/kubeadm/app/cmd/util"
@@ -66,6 +65,7 @@ type controlplaneUpgradeFlags struct {
 	kubeConfigPath   string
 	advertiseAddress string
 	nodeName         string
+	etcdUpgrade      bool
 	dryRun           bool
 }
 
@@ -113,6 +113,7 @@ func NewCmdUpgradeControlPlane() *cobra.Command {
 	flags := &controlplaneUpgradeFlags{
 		kubeConfigPath:   constants.GetKubeletKubeConfigPath(),
 		advertiseAddress: "",
+		etcdUpgrade:      true,
 		dryRun:           false,
 	}
 
@@ -149,6 +150,7 @@ func NewCmdUpgradeControlPlane() *cobra.Command {
 
 	options.AddKubeConfigFlag(cmd.Flags(), &flags.kubeConfigPath)
 	cmd.Flags().BoolVar(&flags.dryRun, "dry-run", flags.dryRun, "Do not change any state, just output the actions that would be performed.")
+	cmd.Flags().BoolVar(&flags.etcdUpgrade, "etcd-upgrade", flags.etcdUpgrade, "Perform the upgrade of etcd.")
 	return cmd
 }
 
@@ -236,13 +238,13 @@ func RunUpgradeControlPlane(flags *controlplaneUpgradeFlags) error {
 		return fmt.Errorf("Unable to rotate API server certificate: %v", err)
 	}
 
-	// Upgrade the control plane
+	// Upgrade the control plane and etcd if installed on this node
 	fmt.Printf("[upgrade] Upgrading your Static Pod-hosted control plane instance to version %q...\n", cfg.KubernetesVersion)
 	if flags.dryRun {
 		return DryRunStaticPodUpgrade(cfg)
 	}
 
-	if err := PerformStaticPodUpgrade(client, waiter, cfg, false); err != nil {
+	if err := PerformStaticPodUpgrade(client, waiter, cfg, flags.etcdUpgrade); err != nil {
 		return fmt.Errorf("Couldn't complete the static pod upgrade: %v", err)
 	}
 

cmd/kubeadm/app/cmd/upgrade/plan.go

@@ -26,7 +26,6 @@ import (
 
 	"github.com/golang/glog"
 	"github.com/spf13/cobra"
-
 	"k8s.io/apimachinery/pkg/util/version"
 	kubeadmapiv1beta1 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1beta1"
 	"k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/validation"
@@ -111,11 +110,8 @@ func RunPlan(flags *planFlags) error {
 		}
 		etcdClient = client
 	} else {
-		client, err := etcdutil.NewFromStaticPod(
-			[]string{fmt.Sprintf("localhost:%d", constants.EtcdListenClientPort)},
-			constants.GetStaticPodDirectory(),
-			upgradeVars.cfg.CertificatesDir,
-		)
+		// Connects to local/stacked etcd existing in the cluster
+		client, err := etcdutil.NewFromCluster(upgradeVars.client, upgradeVars.cfg.CertificatesDir)
 		if err != nil {
 			return err
 		}

cmd/kubeadm/app/phases/certs/certs.go

@@ -24,7 +24,6 @@ import (
 	"path/filepath"
 
 	"github.com/golang/glog"
-
 	certutil "k8s.io/client-go/util/cert"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
@@ -285,7 +284,7 @@ type certKeyLocation struct {
 }
 
 // SharedCertificateExists verifies if the shared certificates - the certificates that must be
-// equal across masters: ca.key, ca.crt, sa.key, sa.pub
+// equal across masters: ca.key, ca.crt, sa.key, sa.pub + etcd/ca.key, etcd/ca.crt if local/stacked etcd
 func SharedCertificateExists(cfg *kubeadmapi.InitConfiguration) (bool, error) {
 
 	if err := validateCACertAndKey(certKeyLocation{cfg.CertificatesDir, kubeadmconstants.CACertAndKeyBaseName, "", "CA"}); err != nil {
@@ -300,6 +299,13 @@ func SharedCertificateExists(cfg *kubeadmapi.InitConfiguration) (bool, error) {
 		return false, err
 	}
 
+	// in case of local/stacked etcd
+	if cfg.Etcd.External == nil {
+		if err := validateCACertAndKey(certKeyLocation{cfg.CertificatesDir, kubeadmconstants.EtcdCACertAndKeyBaseName, "", "etcd CA"}); err != nil {
+			return false, err
+		}
+	}
+
 	return true, nil
 }
 

cmd/kubeadm/app/phases/certs/certs_test.go

@@ -308,6 +308,8 @@ func TestSharedCertificateExists(t *testing.T) {
 				"front-proxy-ca.key": caKey,
 				"sa.pub":             publicKey,
 				"sa.key":             key,
+				"etcd/ca.crt":        caCert,
+				"etcd/ca.key":        caKey,
 			},
 		},
 		{
@@ -318,6 +320,8 @@ func TestSharedCertificateExists(t *testing.T) {
 				"front-proxy-ca.key": caKey,
 				"sa.pub":             publicKey,
 				"sa.key":             key,
+				"etcd/ca.crt":        caCert,
+				"etcd/ca.key":        caKey,
 			},
 			expectedError: true,
 		},
@@ -329,17 +333,34 @@ func TestSharedCertificateExists(t *testing.T) {
 				"front-proxy-ca.crt": caCert,
 				"front-proxy-ca.key": caKey,
 				"sa.pub":             publicKey,
+				"etcd/ca.crt":        caCert,
+				"etcd/ca.key":        caKey,
 			},
 			expectedError: true,
 		},
 		{
-			name: "expected front-proxy.crt missing",
+			name: "missing front-proxy.crt",
 			files: pkiFiles{
 				"ca.crt":             caCert,
 				"ca.key":             caKey,
 				"front-proxy-ca.key": caKey,
 				"sa.pub":             publicKey,
 				"sa.key":             key,
+				"etcd/ca.crt":        caCert,
+				"etcd/ca.key":        caKey,
+			},
+			expectedError: true,
+		},
+		{
+			name: "missing etcd/ca.crt",
+			files: pkiFiles{
+				"ca.crt":             caCert,
+				"ca.key":             caKey,
+				"front-proxy-ca.key": caKey,
+				"sa.pub":             publicKey,
+				"sa.key":             key,
+				"etcd/ca.crt":        caCert,
+				"etcd/ca.key":        caKey,
 			},
 			expectedError: true,
 		},
@@ -348,6 +369,7 @@ func TestSharedCertificateExists(t *testing.T) {
 	for _, test := range tests {
 		t.Run("", func(t *testing.T) {
 			tmpdir := testutil.SetupTempDir(t)
+			os.MkdirAll(tmpdir+"/etcd", os.ModePerm)
 			defer os.RemoveAll(tmpdir)
 
 			cfg := &kubeadmapi.InitConfiguration{

cmd/kubeadm/app/phases/certs/pkiutil/BUILD

@@ -27,6 +27,7 @@ go_library(
         "//pkg/registry/core/service/ipallocator:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/validation:go_default_library",
         "//staging/src/k8s.io/client-go/util/cert:go_default_library",
+        "//vendor/github.com/pkg/errors:go_default_library",
     ],
 )
 

cmd/kubeadm/app/phases/certs/pkiutil/pki_helpers.go

@@ -25,6 +25,7 @@ import (
 	"path/filepath"
 	"time"
 
+	"github.com/pkg/errors"
 	"k8s.io/apimachinery/pkg/util/validation"
 	certutil "k8s.io/client-go/util/cert"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
@@ -304,14 +305,19 @@ func GetAPIServerAltNames(cfg *kubeadmapi.InitConfiguration) (*certutil.AltNames
 }
 
 // GetEtcdAltNames builds an AltNames object for generating the etcd server certificate.
-// `localhost` is included in the SAN since this is the interface the etcd static pod listens on.
-// Hostname and `API.AdvertiseAddress` are excluded since etcd does not listen on this interface by default.
+// `advertise address` and localhost are included in the SAN since this is the interfaces the etcd static pod listens on.
 // The user can override the listen address with `Etcd.ExtraArgs` and add SANs with `Etcd.ServerCertSANs`.
 func GetEtcdAltNames(cfg *kubeadmapi.InitConfiguration) (*certutil.AltNames, error) {
+	// advertise address
+	advertiseAddress := net.ParseIP(cfg.APIEndpoint.AdvertiseAddress)
+	if advertiseAddress == nil {
+		return nil, errors.Errorf("error parsing APIEndpoint AdvertiseAddress %q: is not a valid textual representation of an IP address", cfg.APIEndpoint.AdvertiseAddress)
+	}
+
 	// create AltNames with defaults DNSNames/IPs
 	altNames := &certutil.AltNames{
 		DNSNames: []string{cfg.NodeRegistration.Name, "localhost"},
-		IPs:      []net.IP{net.IPv4(127, 0, 0, 1), net.IPv6loopback},
+		IPs:      []net.IP{advertiseAddress, net.IPv4(127, 0, 0, 1), net.IPv6loopback},
 	}
 
 	if cfg.Etcd.Local != nil {
@@ -322,8 +328,7 @@ func GetEtcdAltNames(cfg *kubeadmapi.InitConfiguration) (*certutil.AltNames, err
 }
 
 // GetEtcdPeerAltNames builds an AltNames object for generating the etcd peer certificate.
-// `localhost` is excluded from the SAN since etcd will not refer to itself as a peer.
-// Hostname and `API.AdvertiseAddress` are included if the user chooses to promote the single node etcd cluster into a multi-node one.
+// Hostname and `API.AdvertiseAddress` are included if the user chooses to promote the single node etcd cluster into a multi-node one (stacked etcd).
 // The user can override the listen address with `Etcd.ExtraArgs` and add SANs with `Etcd.PeerCertSANs`.
 func GetEtcdPeerAltNames(cfg *kubeadmapi.InitConfiguration) (*certutil.AltNames, error) {
 	// advertise address

cmd/kubeadm/app/phases/certs/pkiutil/pki_helpers_test.go

@@ -513,6 +513,12 @@ func TestGetEtcdAltNames(t *testing.T) {
 	proxy := "user-etcd-proxy"
 	proxyIP := "10.10.10.100"
 	cfg := &kubeadmapi.InitConfiguration{
+		APIEndpoint: kubeadmapi.APIEndpoint{
+			AdvertiseAddress: "1.2.3.4",
+		},
+		NodeRegistration: kubeadmapi.NodeRegistrationOptions{
+			Name: "myNode",
+		},
 		ClusterConfiguration: kubeadmapi.ClusterConfiguration{
 			Etcd: kubeadmapi.Etcd{
 				Local: &kubeadmapi.LocalEtcd{
@@ -532,7 +538,7 @@ func TestGetEtcdAltNames(t *testing.T) {
 		t.Fatalf("failed calling GetEtcdAltNames: %v", err)
 	}
 
-	expectedDNSNames := []string{"localhost", proxy}
+	expectedDNSNames := []string{"myNode", "localhost", proxy}
 	for _, DNSName := range expectedDNSNames {
 		found := false
 		for _, val := range altNames.DNSNames {
@@ -547,7 +553,7 @@ func TestGetEtcdAltNames(t *testing.T) {
 		}
 	}
 
-	expectedIPAddresses := []string{"127.0.0.1", net.IPv6loopback.String(), proxyIP}
+	expectedIPAddresses := []string{"1.2.3.4", "127.0.0.1", net.IPv6loopback.String(), proxyIP}
 	for _, IPAddress := range expectedIPAddresses {
 		found := false
 		for _, val := range altNames.IPs {

cmd/kubeadm/app/phases/etcd/BUILD

@@ -13,6 +13,7 @@ go_test(
     deps = [
         "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
         "//cmd/kubeadm/app/constants:go_default_library",
+        "//cmd/kubeadm/app/util/etcd:go_default_library",
         "//cmd/kubeadm/test:go_default_library",
     ],
 )
@@ -26,9 +27,12 @@ go_library(
         "//cmd/kubeadm/app/constants:go_default_library",
         "//cmd/kubeadm/app/images:go_default_library",
         "//cmd/kubeadm/app/util:go_default_library",
+        "//cmd/kubeadm/app/util/etcd:go_default_library",
         "//cmd/kubeadm/app/util/staticpod:go_default_library",
         "//staging/src/k8s.io/api/core/v1:go_default_library",
+        "//staging/src/k8s.io/client-go/kubernetes:go_default_library",
         "//vendor/github.com/golang/glog:go_default_library",
+        "//vendor/github.com/pkg/errors:go_default_library",
     ],
 )
 

cmd/kubeadm/app/phases/etcd/local.go

@@ -19,14 +19,17 @@ package etcd
 import (
 	"fmt"
 	"path/filepath"
+	"strings"
 
 	"github.com/golang/glog"
-
+	"github.com/pkg/errors"
 	"k8s.io/api/core/v1"
+	clientset "k8s.io/client-go/kubernetes"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	"k8s.io/kubernetes/cmd/kubeadm/app/images"
 	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
+	etcdutil "k8s.io/kubernetes/cmd/kubeadm/app/util/etcd"
 	staticpodutil "k8s.io/kubernetes/cmd/kubeadm/app/util/staticpod"
 )
 
@@ -36,13 +39,70 @@ const (
 )
 
 // CreateLocalEtcdStaticPodManifestFile will write local etcd static pod manifest file.
+// This function is used by init - when the etcd cluster is empty - or by kubeadm
+// upgrade - when the etcd cluster is already up and running (and the --initial-cluster flag have no impact)
 func CreateLocalEtcdStaticPodManifestFile(manifestDir string, cfg *kubeadmapi.InitConfiguration) error {
 	if cfg.ClusterConfiguration.Etcd.External != nil {
 		return fmt.Errorf("etcd static pod manifest cannot be generated for cluster using external etcd")
 	}
 	glog.V(1).Infoln("creating local etcd static pod manifest file")
-	// gets etcd StaticPodSpec, actualized for the current InitConfiguration
-	spec := GetEtcdPodSpec(cfg)
+	// gets etcd StaticPodSpec
+	emptyInitialCluster := []etcdutil.Member{}
+	spec := GetEtcdPodSpec(cfg, emptyInitialCluster)
+	// writes etcd StaticPod to disk
+	if err := staticpodutil.WriteStaticPodToDisk(kubeadmconstants.Etcd, manifestDir, spec); err != nil {
+		return err
+	}
+
+	fmt.Printf("[etcd] Wrote Static Pod manifest for a local etcd instance to %q\n", kubeadmconstants.GetStaticPodFilepath(kubeadmconstants.Etcd, manifestDir))
+	return nil
+}
+
+// CheckLocalEtcdClusterStatus verifies health state of local/stacked etcd cluster before installing a new etcd member
+func CheckLocalEtcdClusterStatus(client clientset.Interface, cfg *kubeadmapi.InitConfiguration) error {
+	fmt.Println("[etcd] Checking Etcd cluster health")
+
+	// creates an etcd client that connects to all the local/stacked etcd members
+	glog.V(1).Info("creating etcd client that connects to etcd pods")
+	etcdClient, err := etcdutil.NewFromCluster(client, cfg.CertificatesDir)
+	if err != nil {
+		return err
+	}
+
+	// Checking health state
+	_, err = etcdClient.GetClusterStatus()
+	if err != nil {
+		return errors.Wrap(err, "etcd cluster is not healthy")
+	}
+
+	return nil
+}
+
+// CreateStackedEtcdStaticPodManifestFile will write local etcd static pod manifest file
+// for an additional etcd member that is joining an existing local/stacked etcd cluster.
+// Other members of the etcd cluster will be notified of the joining node in beforehand as well.
+func CreateStackedEtcdStaticPodManifestFile(client clientset.Interface, manifestDir string, cfg *kubeadmapi.InitConfiguration) error {
+	// creates an etcd client that connects to all the local/stacked etcd members
+	glog.V(1).Info("creating etcd client that connects to etcd pods")
+	etcdClient, err := etcdutil.NewFromCluster(client, cfg.CertificatesDir)
+	if err != nil {
+		return err
+	}
+
+	// notifies the other members of the etcd cluster about the joining member
+	etcdPeerAddress := fmt.Sprintf("https://%s:%d", cfg.APIEndpoint.AdvertiseAddress, kubeadmconstants.EtcdListenPeerPort)
+
+	glog.V(1).Infof("Adding etcd member: %s", etcdPeerAddress)
+	initialCluster, err := etcdClient.AddMember(cfg.NodeRegistration.Name, etcdPeerAddress)
+	if err != nil {
+		return err
+	}
+	fmt.Println("[etcd] Announced new etcd member joining to the existing etcd cluster")
+	glog.V(1).Infof("Updated etcd member list: %v", initialCluster)
+
+	glog.V(1).Info("Creating local etcd static pod manifest file")
+	// gets etcd StaticPodSpec, actualized for the current InitConfiguration and the new list of etcd members
+	spec := GetEtcdPodSpec(cfg, initialCluster)
 	// writes etcd StaticPod to disk
 	if err := staticpodutil.WriteStaticPodToDisk(kubeadmconstants.Etcd, manifestDir, spec); err != nil {
 		return err
@@ -54,7 +114,7 @@ func CreateLocalEtcdStaticPodManifestFile(manifestDir string, cfg *kubeadmapi.In
 
 // GetEtcdPodSpec returns the etcd static Pod actualized to the context of the current InitConfiguration
 // NB. GetEtcdPodSpec methods holds the information about how kubeadm creates etcd static pod manifests.
-func GetEtcdPodSpec(cfg *kubeadmapi.InitConfiguration) v1.Pod {
+func GetEtcdPodSpec(cfg *kubeadmapi.InitConfiguration, initialCluster []etcdutil.Member) v1.Pod {
 	pathType := v1.HostPathDirectoryOrCreate
 	etcdMounts := map[string]v1.Volume{
 		etcdVolumeName:  staticpodutil.NewVolume(etcdVolumeName, cfg.Etcd.Local.DataDir, &pathType),
@@ -62,7 +122,7 @@ func GetEtcdPodSpec(cfg *kubeadmapi.InitConfiguration) v1.Pod {
 	}
 	return staticpodutil.ComponentPod(v1.Container{
 		Name:            kubeadmconstants.Etcd,
-		Command:         getEtcdCommand(cfg),
+		Command:         getEtcdCommand(cfg, initialCluster),
 		Image:           images.GetEtcdImage(&cfg.ClusterConfiguration),
 		ImagePullPolicy: v1.PullIfNotPresent,
 		// Mount the etcd datadir path read-write so etcd can store data in a more persistent manner
@@ -78,13 +138,13 @@ func GetEtcdPodSpec(cfg *kubeadmapi.InitConfiguration) v1.Pod {
 }
 
 // getEtcdCommand builds the right etcd command from the given config object
-func getEtcdCommand(cfg *kubeadmapi.InitConfiguration) []string {
+func getEtcdCommand(cfg *kubeadmapi.InitConfiguration, initialCluster []etcdutil.Member) []string {
 	defaultArguments := map[string]string{
 		"name":                        cfg.GetNodeName(),
-		"listen-client-urls":          fmt.Sprintf("https://127.0.0.1:%d", kubeadmconstants.EtcdListenClientPort),
-		"advertise-client-urls":       fmt.Sprintf("https://127.0.0.1:%d", kubeadmconstants.EtcdListenClientPort),
-		"listen-peer-urls":            fmt.Sprintf("https://127.0.0.1:%d", kubeadmconstants.EtcdListenPeerPort),
-		"initial-advertise-peer-urls": fmt.Sprintf("https://127.0.0.1:%d", kubeadmconstants.EtcdListenPeerPort),
+		"listen-client-urls":          fmt.Sprintf("https://127.0.0.1:%d,https://%s:%d", kubeadmconstants.EtcdListenClientPort, cfg.APIEndpoint.AdvertiseAddress, kubeadmconstants.EtcdListenClientPort),
+		"advertise-client-urls":       fmt.Sprintf("https://%s:%d", cfg.APIEndpoint.AdvertiseAddress, kubeadmconstants.EtcdListenClientPort),
+		"listen-peer-urls":            fmt.Sprintf("https://%s:%d", cfg.APIEndpoint.AdvertiseAddress, kubeadmconstants.EtcdListenPeerPort),
+		"initial-advertise-peer-urls": fmt.Sprintf("https://%s:%d", cfg.APIEndpoint.AdvertiseAddress, kubeadmconstants.EtcdListenPeerPort),
 		"data-dir":                    cfg.Etcd.Local.DataDir,
 		"cert-file":                   filepath.Join(cfg.CertificatesDir, kubeadmconstants.EtcdServerCertName),
 		"key-file":                    filepath.Join(cfg.CertificatesDir, kubeadmconstants.EtcdServerKeyName),
@@ -95,7 +155,19 @@ func getEtcdCommand(cfg *kubeadmapi.InitConfiguration) []string {
 		"peer-trusted-ca-file":        filepath.Join(cfg.CertificatesDir, kubeadmconstants.EtcdCACertName),
 		"peer-client-cert-auth":       "true",
 		"snapshot-count":              "10000",
-		"initial-cluster":             fmt.Sprintf("%s=https://127.0.0.1:%d", cfg.GetNodeName(), kubeadmconstants.EtcdListenPeerPort),
+	}
+
+	if len(initialCluster) == 0 {
+		defaultArguments["initial-cluster"] = fmt.Sprintf("%s=https://%s:%d", cfg.GetNodeName(), cfg.APIEndpoint.AdvertiseAddress, kubeadmconstants.EtcdListenPeerPort)
+	} else {
+		// NB. the joining etcd instance should be part of the initialCluster list
+		endpoints := []string{}
+		for _, member := range initialCluster {
+			endpoints = append(endpoints, fmt.Sprintf("%s=%s", member.Name, member.PeerURL))
+		}
+
+		defaultArguments["initial-cluster"] = strings.Join(endpoints, ",")
+		defaultArguments["initial-cluster-state"] = "existing"
 	}
 
 	command := []string{"etcd"}

cmd/kubeadm/app/phases/etcd/local_test.go

@@ -26,12 +26,11 @@ import (
 
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
-
+	etcdutil "k8s.io/kubernetes/cmd/kubeadm/app/util/etcd"
 	testutil "k8s.io/kubernetes/cmd/kubeadm/test"
 )
 
 func TestGetEtcdPodSpec(t *testing.T) {
-
 	// Creates a Master Configuration
 	cfg := &kubeadmapi.InitConfiguration{
 		ClusterConfiguration: kubeadmapi.ClusterConfiguration{
@@ -46,7 +45,7 @@ func TestGetEtcdPodSpec(t *testing.T) {
 	}
 
 	// Executes GetEtcdPodSpec
-	spec := GetEtcdPodSpec(cfg)
+	spec := GetEtcdPodSpec(cfg, []etcdutil.Member{})
 
 	// Assert each specs refers to the right pod
 	if spec.Spec.Containers[0].Name != kubeadmconstants.Etcd {
@@ -117,11 +116,17 @@ func TestCreateLocalEtcdStaticPodManifestFile(t *testing.T) {
 
 func TestGetEtcdCommand(t *testing.T) {
 	var tests = []struct {
-		cfg      *kubeadmapi.InitConfiguration
-		expected []string
+		name           string
+		cfg            *kubeadmapi.InitConfiguration
+		initialCluster []etcdutil.Member
+		expected       []string
 	}{
 		{
+			name: "Default args - with empty etcd initial cluster",
 			cfg: &kubeadmapi.InitConfiguration{
+				APIEndpoint: kubeadmapi.APIEndpoint{
+					AdvertiseAddress: "1.2.3.4",
+				},
 				NodeRegistration: kubeadmapi.NodeRegistrationOptions{
 					Name: "foo",
 				},
@@ -136,10 +141,10 @@ func TestGetEtcdCommand(t *testing.T) {
 			expected: []string{
 				"etcd",
 				"--name=foo",
-				fmt.Sprintf("--listen-client-urls=https://127.0.0.1:%d", kubeadmconstants.EtcdListenClientPort),
-				fmt.Sprintf("--advertise-client-urls=https://127.0.0.1:%d", kubeadmconstants.EtcdListenClientPort),
-				fmt.Sprintf("--listen-peer-urls=https://127.0.0.1:%d", kubeadmconstants.EtcdListenPeerPort),
-				fmt.Sprintf("--initial-advertise-peer-urls=https://127.0.0.1:%d", kubeadmconstants.EtcdListenPeerPort),
+				fmt.Sprintf("--listen-client-urls=https://127.0.0.1:%d,https://1.2.3.4:%d", kubeadmconstants.EtcdListenClientPort, kubeadmconstants.EtcdListenClientPort),
+				fmt.Sprintf("--advertise-client-urls=https://1.2.3.4:%d", kubeadmconstants.EtcdListenClientPort),
+				fmt.Sprintf("--listen-peer-urls=https://1.2.3.4:%d", kubeadmconstants.EtcdListenPeerPort),
+				fmt.Sprintf("--initial-advertise-peer-urls=https://1.2.3.4:%d", kubeadmconstants.EtcdListenPeerPort),
 				"--data-dir=/var/lib/etcd",
 				"--cert-file=" + kubeadmconstants.EtcdServerCertName,
 				"--key-file=" + kubeadmconstants.EtcdServerKeyName,
@@ -150,33 +155,37 @@ func TestGetEtcdCommand(t *testing.T) {
 				"--peer-trusted-ca-file=" + kubeadmconstants.EtcdCACertName,
 				"--snapshot-count=10000",
 				"--peer-client-cert-auth=true",
-				fmt.Sprintf("--initial-cluster=foo=https://127.0.0.1:%d", kubeadmconstants.EtcdListenPeerPort),
+				fmt.Sprintf("--initial-cluster=foo=https://1.2.3.4:%d", kubeadmconstants.EtcdListenPeerPort),
 			},
 		},
 		{
+			name: "Default args - With an existing etcd cluster",
 			cfg: &kubeadmapi.InitConfiguration{
+				APIEndpoint: kubeadmapi.APIEndpoint{
+					AdvertiseAddress: "1.2.3.4",
+				},
 				NodeRegistration: kubeadmapi.NodeRegistrationOptions{
-					Name: "bar",
+					Name: "foo",
 				},
 				ClusterConfiguration: kubeadmapi.ClusterConfiguration{
 					Etcd: kubeadmapi.Etcd{
 						Local: &kubeadmapi.LocalEtcd{
 							DataDir: "/var/lib/etcd",
-							ExtraArgs: map[string]string{
-								"listen-client-urls":    "https://10.0.1.10:2379",
-								"advertise-client-urls": "https://10.0.1.10:2379",
-							},
 						},
 					},
 				},
 			},
+			initialCluster: []etcdutil.Member{
+				{Name: "foo", PeerURL: fmt.Sprintf("https://1.2.3.4:%d", kubeadmconstants.EtcdListenPeerPort)}, // NB. the joining etcd instance should be part of the initialCluster list
+				{Name: "bar", PeerURL: fmt.Sprintf("https://5.6.7.8:%d", kubeadmconstants.EtcdListenPeerPort)},
+			},
 			expected: []string{
 				"etcd",
-				"--name=bar",
-				"--listen-client-urls=https://10.0.1.10:2379",
-				"--advertise-client-urls=https://10.0.1.10:2379",
-				fmt.Sprintf("--listen-peer-urls=https://127.0.0.1:%d", kubeadmconstants.EtcdListenPeerPort),
-				fmt.Sprintf("--initial-advertise-peer-urls=https://127.0.0.1:%d", kubeadmconstants.EtcdListenPeerPort),
+				"--name=foo",
+				fmt.Sprintf("--listen-client-urls=https://127.0.0.1:%d,https://1.2.3.4:%d", kubeadmconstants.EtcdListenClientPort, kubeadmconstants.EtcdListenClientPort),
+				fmt.Sprintf("--advertise-client-urls=https://1.2.3.4:%d", kubeadmconstants.EtcdListenClientPort),
+				fmt.Sprintf("--listen-peer-urls=https://1.2.3.4:%d", kubeadmconstants.EtcdListenPeerPort),
+				fmt.Sprintf("--initial-advertise-peer-urls=https://1.2.3.4:%d", kubeadmconstants.EtcdListenPeerPort),
 				"--data-dir=/var/lib/etcd",
 				"--cert-file=" + kubeadmconstants.EtcdServerCertName,
 				"--key-file=" + kubeadmconstants.EtcdServerKeyName,
@@ -187,30 +196,39 @@ func TestGetEtcdCommand(t *testing.T) {
 				"--peer-trusted-ca-file=" + kubeadmconstants.EtcdCACertName,
 				"--snapshot-count=10000",
 				"--peer-client-cert-auth=true",
-				fmt.Sprintf("--initial-cluster=bar=https://127.0.0.1:%d", kubeadmconstants.EtcdListenPeerPort),
+				"--initial-cluster-state=existing",
+				fmt.Sprintf("--initial-cluster=foo=https://1.2.3.4:%d,bar=https://5.6.7.8:%d", kubeadmconstants.EtcdListenPeerPort, kubeadmconstants.EtcdListenPeerPort),
 			},
 		},
 		{
+			name: "Extra args",
 			cfg: &kubeadmapi.InitConfiguration{
+				APIEndpoint: kubeadmapi.APIEndpoint{
+					AdvertiseAddress: "1.2.3.4",
+				},
 				NodeRegistration: kubeadmapi.NodeRegistrationOptions{
-					Name: "wombat",
+					Name: "bar",
 				},
 				ClusterConfiguration: kubeadmapi.ClusterConfiguration{
 					Etcd: kubeadmapi.Etcd{
 						Local: &kubeadmapi.LocalEtcd{
-							DataDir: "/etc/foo",
+							DataDir: "/var/lib/etcd",
+							ExtraArgs: map[string]string{
+								"listen-client-urls":    "https://10.0.1.10:2379",
+								"advertise-client-urls": "https://10.0.1.10:2379",
+							},
 						},
 					},
 				},
 			},
 			expected: []string{
 				"etcd",
-				"--name=wombat",
-				fmt.Sprintf("--listen-client-urls=https://127.0.0.1:%d", kubeadmconstants.EtcdListenClientPort),
-				fmt.Sprintf("--advertise-client-urls=https://127.0.0.1:%d", kubeadmconstants.EtcdListenClientPort),
-				fmt.Sprintf("--listen-peer-urls=https://127.0.0.1:%d", kubeadmconstants.EtcdListenPeerPort),
-				fmt.Sprintf("--initial-advertise-peer-urls=https://127.0.0.1:%d", kubeadmconstants.EtcdListenPeerPort),
-				"--data-dir=/etc/foo",
+				"--name=bar",
+				"--listen-client-urls=https://10.0.1.10:2379",
+				"--advertise-client-urls=https://10.0.1.10:2379",
+				fmt.Sprintf("--listen-peer-urls=https://1.2.3.4:%d", kubeadmconstants.EtcdListenPeerPort),
+				fmt.Sprintf("--initial-advertise-peer-urls=https://1.2.3.4:%d", kubeadmconstants.EtcdListenPeerPort),
+				"--data-dir=/var/lib/etcd",
 				"--cert-file=" + kubeadmconstants.EtcdServerCertName,
 				"--key-file=" + kubeadmconstants.EtcdServerKeyName,
 				"--trusted-ca-file=" + kubeadmconstants.EtcdCACertName,
@@ -220,17 +238,19 @@ func TestGetEtcdCommand(t *testing.T) {
 				"--peer-trusted-ca-file=" + kubeadmconstants.EtcdCACertName,
 				"--snapshot-count=10000",
 				"--peer-client-cert-auth=true",
-				fmt.Sprintf("--initial-cluster=wombat=https://127.0.0.1:%d", kubeadmconstants.EtcdListenPeerPort),
+				fmt.Sprintf("--initial-cluster=bar=https://1.2.3.4:%d", kubeadmconstants.EtcdListenPeerPort),
 			},
 		},
 	}
 
 	for _, rt := range tests {
-		actual := getEtcdCommand(rt.cfg)
-		sort.Strings(actual)
-		sort.Strings(rt.expected)
-		if !reflect.DeepEqual(actual, rt.expected) {
-			t.Errorf("failed getEtcdCommand:\nexpected:\n%v\nsaw:\n%v", rt.expected, actual)
-		}
+		t.Run(rt.name, func(t *testing.T) {
+			actual := getEtcdCommand(rt.cfg, rt.initialCluster)
+			sort.Strings(actual)
+			sort.Strings(rt.expected)
+			if !reflect.DeepEqual(actual, rt.expected) {
+				t.Errorf("failed getEtcdCommand:\nexpected:\n%v\nsaw:\n%v", rt.expected, actual)
+			}
+		})
 	}
 }

cmd/kubeadm/app/phases/upgrade/compute_test.go

@@ -107,6 +107,12 @@ func (f fakeEtcdClient) GetClusterVersions() (map[string]string, error) {
 	}, nil
 }
 
+func (f fakeEtcdClient) Sync() error { return nil }
+
+func (f fakeEtcdClient) AddMember(name string, peerAddrs string) ([]etcdutil.Member, error) {
+	return []etcdutil.Member{}, nil
+}
+
 func TestGetAvailableUpgrades(t *testing.T) {
 	etcdClient := fakeEtcdClient{}
 	tests := []struct {

cmd/kubeadm/app/phases/upgrade/staticpods.go

@@ -23,8 +23,8 @@ import (
 	"time"
 
 	"github.com/pkg/errors"
-
 	"k8s.io/apimachinery/pkg/util/version"
+	clientset "k8s.io/client-go/kubernetes"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	certsphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/certs"
@@ -252,7 +252,7 @@ func upgradeComponent(component string, waiter apiclient.Waiter, pathMgr StaticP
 }
 
 // performEtcdStaticPodUpgrade performs upgrade of etcd, it returns bool which indicates fatal error or not and the actual error.
-func performEtcdStaticPodUpgrade(waiter apiclient.Waiter, pathMgr StaticPodPathManager, cfg *kubeadmapi.InitConfiguration, recoverManifests map[string]string, isTLSUpgrade bool, oldEtcdClient, newEtcdClient etcdutil.ClusterInterrogator) (bool, error) {
+func performEtcdStaticPodUpgrade(client clientset.Interface, waiter apiclient.Waiter, pathMgr StaticPodPathManager, cfg *kubeadmapi.InitConfiguration, recoverManifests map[string]string, isTLSUpgrade bool, oldEtcdClient, newEtcdClient etcdutil.ClusterInterrogator) (bool, error) {
 	// Add etcd static pod spec only if external etcd is not configured
 	if cfg.Etcd.External != nil {
 		return false, errors.New("external etcd detected, won't try to change any etcd state")
@@ -276,10 +276,18 @@ func performEtcdStaticPodUpgrade(waiter apiclient.Waiter, pathMgr StaticPodPathM
 	if err != nil {
 		return true, errors.Wrap(err, "failed to retrieve an etcd version for the target kubernetes version")
 	}
-	currentEtcdVersionStr, err := oldEtcdClient.GetVersion()
+
+	// gets the etcd version of the local/stacked etcd member running on the current machine
+	currentEtcdVersions, err := oldEtcdClient.GetClusterVersions()
 	if err != nil {
 		return true, errors.Wrap(err, "failed to retrieve the current etcd version")
 	}
+	currentEtcdVersionStr, ok := currentEtcdVersions[fmt.Sprintf("https://%s:%d", cfg.APIEndpoint.AdvertiseAddress, constants.EtcdListenClientPort)]
+	if !ok {
+		fmt.Println(currentEtcdVersions)
+		return true, errors.Wrap(err, "failed to retrieve the current etcd version")
+	}
+
 	currentEtcdVersion, err := version.ParseSemantic(currentEtcdVersionStr)
 	if err != nil {
 		return true, fmt.Errorf("failed to parse the current etcd version(%s): %v", currentEtcdVersionStr, err)
@@ -353,15 +361,11 @@ func performEtcdStaticPodUpgrade(waiter apiclient.Waiter, pathMgr StaticPodPathM
 
 	// Initialize the new etcd client if it wasn't pre-initialized
 	if newEtcdClient == nil {
-		client, err := etcdutil.NewFromStaticPod(
-			[]string{fmt.Sprintf("localhost:%d", constants.EtcdListenClientPort)},
-			constants.GetStaticPodDirectory(),
-			cfg.CertificatesDir,
-		)
+		etcdClient, err := etcdutil.NewFromCluster(client, cfg.CertificatesDir)
 		if err != nil {
 			return true, errors.Wrap(err, "fatal error creating etcd client")
 		}
-		newEtcdClient = client
+		newEtcdClient = etcdClient
 	}
 
 	// Checking health state of etcd after the upgrade
@@ -399,7 +403,7 @@ func performEtcdStaticPodUpgrade(waiter apiclient.Waiter, pathMgr StaticPodPathM
 }
 
 // StaticPodControlPlane upgrades a static pod-hosted control plane
-func StaticPodControlPlane(waiter apiclient.Waiter, pathMgr StaticPodPathManager, cfg *kubeadmapi.InitConfiguration, etcdUpgrade bool, oldEtcdClient, newEtcdClient etcdutil.ClusterInterrogator) error {
+func StaticPodControlPlane(client clientset.Interface, waiter apiclient.Waiter, pathMgr StaticPodPathManager, cfg *kubeadmapi.InitConfiguration, etcdUpgrade bool, oldEtcdClient, newEtcdClient etcdutil.ClusterInterrogator) error {
 	recoverManifests := map[string]string{}
 	var isTLSUpgrade bool
 	var isExternalEtcd bool
@@ -413,7 +417,7 @@ func StaticPodControlPlane(waiter apiclient.Waiter, pathMgr StaticPodPathManager
 		if cfg.Etcd.External != nil {
 			// External etcd
 			isExternalEtcd = true
-			client, err := etcdutil.New(
+			etcdClient, err := etcdutil.New(
 				cfg.Etcd.External.Endpoints,
 				cfg.Etcd.External.CAFile,
 				cfg.Etcd.External.CertFile,
@@ -422,22 +426,18 @@ func StaticPodControlPlane(waiter apiclient.Waiter, pathMgr StaticPodPathManager
 			if err != nil {
 				return errors.Wrap(err, "failed to create etcd client for external etcd")
 			}
-			oldEtcdClient = client
+			oldEtcdClient = etcdClient
 			// Since etcd is managed externally, the new etcd client will be the same as the old client
 			if newEtcdClient == nil {
-				newEtcdClient = client
+				newEtcdClient = etcdClient
 			}
 		} else {
 			// etcd Static Pod
-			client, err := etcdutil.NewFromStaticPod(
-				[]string{fmt.Sprintf("localhost:%d", constants.EtcdListenClientPort)},
-				constants.GetStaticPodDirectory(),
-				cfg.CertificatesDir,
-			)
+			etcdClient, err := etcdutil.NewFromCluster(client, cfg.CertificatesDir)
 			if err != nil {
 				return errors.Wrap(err, "failed to create etcd client")
 			}
-			oldEtcdClient = client
+			oldEtcdClient = etcdClient
 		}
 	}
 
@@ -452,7 +452,7 @@ func StaticPodControlPlane(waiter apiclient.Waiter, pathMgr StaticPodPathManager
 		}
 
 		// Perform etcd upgrade using common to all control plane components function
-		fatal, err := performEtcdStaticPodUpgrade(waiter, pathMgr, cfg, recoverManifests, isTLSUpgrade, oldEtcdClient, newEtcdClient)
+		fatal, err := performEtcdStaticPodUpgrade(client, waiter, pathMgr, cfg, recoverManifests, isTLSUpgrade, oldEtcdClient, newEtcdClient)
 		if err != nil {
 			if fatal {
 				return err

cmd/kubeadm/app/phases/upgrade/staticpods_test.go

@@ -54,12 +54,13 @@ kind: InitConfiguration
 nodeRegistration:
   name: foo
   criSocket: ""
+apiEndpoint:
+  advertiseAddress: 1.2.3.4
+  bindPort: 6443
 ---
 apiVersion: kubeadm.k8s.io/v1beta1
 kind: ClusterConfiguration
-api:
-  advertiseAddress: 1.2.3.4
-  bindPort: 6443
+
 apiServerCertSANs: null
 apiServerExtraArgs: null
 certificatesDir: %s
@@ -75,9 +76,6 @@ networking:
   dnsDomain: cluster.local
   podSubnet: ""
   serviceSubnet: 10.96.0.0/12
-nodeRegistration:
-  name: foo
-  criSocket: ""
 schedulerExtraArgs: null
 token: ce3aa5.5ec8455bb76b379f
 tokenTTL: 24h
@@ -236,14 +234,14 @@ func (c fakeTLSEtcdClient) WaitForClusterAvailable(delay time.Duration, retries
 
 func (c fakeTLSEtcdClient) GetClusterStatus() (map[string]*clientv3.StatusResponse, error) {
 	return map[string]*clientv3.StatusResponse{
-		"foo": {
+		"https://1.2.3.4:2379": {
 			Version: "3.1.12",
 		}}, nil
 }
 
 func (c fakeTLSEtcdClient) GetClusterVersions() (map[string]string, error) {
 	return map[string]string{
-		"foo": "3.1.12",
+		"https://1.2.3.4:2379": "3.1.12",
 	}, nil
 }
 
@@ -251,6 +249,12 @@ func (c fakeTLSEtcdClient) GetVersion() (string, error) {
 	return "3.1.12", nil
 }
 
+func (c fakeTLSEtcdClient) Sync() error { return nil }
+
+func (c fakeTLSEtcdClient) AddMember(name string, peerAddrs string) ([]etcdutil.Member, error) {
+	return []etcdutil.Member{}, nil
+}
+
 type fakePodManifestEtcdClient struct{ ManifestDir, CertificatesDir string }
 
 func (c fakePodManifestEtcdClient) HasTLS() bool {
@@ -277,13 +281,13 @@ func (c fakePodManifestEtcdClient) GetClusterStatus() (map[string]*clientv3.Stat
 	}
 
 	return map[string]*clientv3.StatusResponse{
-		"foo": {Version: "3.1.12"},
+		"https://1.2.3.4:2379": {Version: "3.1.12"},
 	}, nil
 }
 
 func (c fakePodManifestEtcdClient) GetClusterVersions() (map[string]string, error) {
 	return map[string]string{
-		"foo": "3.1.12",
+		"https://1.2.3.4:2379": "3.1.12",
 	}, nil
 }
 
@@ -291,6 +295,12 @@ func (c fakePodManifestEtcdClient) GetVersion() (string, error) {
 	return "3.1.12", nil
 }
 
+func (c fakePodManifestEtcdClient) Sync() error { return nil }
+
+func (c fakePodManifestEtcdClient) AddMember(name string, peerAddrs string) ([]etcdutil.Member, error) {
+	return []etcdutil.Member{}, nil
+}
+
 func TestStaticPodControlPlane(t *testing.T) {
 	tests := []struct {
 		description          string
@@ -477,6 +487,7 @@ func TestStaticPodControlPlane(t *testing.T) {
 		}
 
 		actualErr := StaticPodControlPlane(
+			nil,
 			waiter,
 			pathMgr,
 			newcfg,

cmd/kubeadm/app/phases/uploadconfig/BUILD

@@ -12,16 +12,13 @@ go_library(
     importpath = "k8s.io/kubernetes/cmd/kubeadm/app/phases/uploadconfig",
     deps = [
         "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
-        "//cmd/kubeadm/app/apis/kubeadm/scheme:go_default_library",
         "//cmd/kubeadm/app/constants:go_default_library",
         "//cmd/kubeadm/app/util/apiclient:go_default_library",
         "//cmd/kubeadm/app/util/config:go_default_library",
         "//pkg/apis/rbac/v1:go_default_library",
         "//staging/src/k8s.io/api/core/v1:go_default_library",
         "//staging/src/k8s.io/api/rbac/v1:go_default_library",
-        "//staging/src/k8s.io/apimachinery/pkg/api/errors:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
-        "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//staging/src/k8s.io/client-go/kubernetes:go_default_library",
     ],
 )
@@ -48,13 +45,10 @@ go_test(
         "//cmd/kubeadm/app/apis/kubeadm/scheme:go_default_library",
         "//cmd/kubeadm/app/apis/kubeadm/v1beta1:go_default_library",
         "//cmd/kubeadm/app/constants:go_default_library",
-        "//cmd/kubeadm/app/util/apiclient:go_default_library",
         "//cmd/kubeadm/app/util/config:go_default_library",
-        "//staging/src/k8s.io/api/core/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/api/errors:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
-        "//staging/src/k8s.io/client-go/kubernetes:go_default_library",
         "//staging/src/k8s.io/client-go/kubernetes/fake:go_default_library",
         "//staging/src/k8s.io/client-go/testing:go_default_library",
     ],

cmd/kubeadm/app/phases/uploadconfig/uploadconfig.go

@@ -21,12 +21,9 @@ import (
 
 	"k8s.io/api/core/v1"
 	rbac "k8s.io/api/rbac/v1"
-	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-	"k8s.io/apimachinery/pkg/runtime"
 	clientset "k8s.io/client-go/kubernetes"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
-	kubeadmscheme "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/scheme"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	"k8s.io/kubernetes/cmd/kubeadm/app/util/apiclient"
 	configutil "k8s.io/kubernetes/cmd/kubeadm/app/util/config"
@@ -59,7 +56,7 @@ func UploadConfiguration(cfg *kubeadmapi.InitConfiguration, client clientset.Int
 	// Prepare the ClusterStatus for upload
 	// Gets the current cluster status
 	// TODO: use configmap locks on this object on the get before the update.
-	clusterStatus, err := getClusterStatus(client)
+	clusterStatus, err := configutil.GetClusterStatus(client)
 	if err != nil {
 		return err
 	}
@@ -129,22 +126,3 @@ func UploadConfiguration(cfg *kubeadmapi.InitConfiguration, client clientset.Int
 		},
 	})
 }
-
-func getClusterStatus(client clientset.Interface) (*kubeadmapi.ClusterStatus, error) {
-	obj := &kubeadmapi.ClusterStatus{}
-
-	// Read the ConfigMap from the cluster
-	configMap, err := client.CoreV1().ConfigMaps(metav1.NamespaceSystem).Get(kubeadmconstants.KubeadmConfigConfigMap, metav1.GetOptions{})
-	if apierrors.IsNotFound(err) {
-		return obj, nil
-	}
-	if err != nil {
-		return nil, err
-	}
-
-	// Decode the file content  using the componentconfig Codecs that knows about all APIs
-	if err := runtime.DecodeInto(kubeadmscheme.Codecs.UniversalDecoder(), []byte(configMap.Data[kubeadmconstants.ClusterStatusConfigMapKey]), obj); err != nil {
-		return nil, err
-	}
-	return obj, nil
-}

cmd/kubeadm/app/phases/uploadconfig/uploadconfig_test.go

@@ -20,18 +20,15 @@ import (
 	"reflect"
 	"testing"
 
-	"k8s.io/api/core/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
-	clientset "k8s.io/client-go/kubernetes"
 	clientsetfake "k8s.io/client-go/kubernetes/fake"
 	core "k8s.io/client-go/testing"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	kubeadmscheme "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/scheme"
 	kubeadmapiv1beta1 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1beta1"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
-	"k8s.io/kubernetes/cmd/kubeadm/app/util/apiclient"
 	configutil "k8s.io/kubernetes/cmd/kubeadm/app/util/config"
 )
 
@@ -158,62 +155,3 @@ func TestUploadConfiguration(t *testing.T) {
 		})
 	}
 }
-
-func TestGetClusterStatus(t *testing.T) {
-	var tests = []struct {
-		name                     string
-		clusterStatus            *kubeadmapi.ClusterStatus
-		expectedClusterEndpoints int
-	}{
-		{
-			name:                     "return empty ClusterStatus if cluster kubeadm-config doesn't exist (e.g init)",
-			expectedClusterEndpoints: 0,
-		},
-		{
-			name: "return ClusterStatus if cluster kubeadm-config exist (e.g upgrade)",
-			clusterStatus: &kubeadmapi.ClusterStatus{
-				APIEndpoints: map[string]kubeadmapi.APIEndpoint{
-					"dummy": {AdvertiseAddress: "1.2.3.4", BindPort: 1234},
-				},
-			},
-			expectedClusterEndpoints: 1,
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			client := clientsetfake.NewSimpleClientset()
-
-			if tt.clusterStatus != nil {
-				createConfigMapWithStatus(tt.clusterStatus, client)
-			}
-
-			actual, err := getClusterStatus(client)
-			if err != nil {
-				t.Error("GetClusterStatus returned unexpected error")
-				return
-			}
-			if tt.expectedClusterEndpoints != len(actual.APIEndpoints) {
-				t.Error("actual ClusterStatus doesn't return expected endpoints")
-			}
-		})
-	}
-}
-
-// createConfigMapWithStatus create a ConfigMap with ClusterStatus for TestGetClusterStatus
-func createConfigMapWithStatus(statusToCreate *kubeadmapi.ClusterStatus, client clientset.Interface) error {
-	statusYaml, err := configutil.MarshalKubeadmConfigObject(statusToCreate)
-	if err != nil {
-		return err
-	}
-
-	return apiclient.CreateOrUpdateConfigMap(client, &v1.ConfigMap{
-		ObjectMeta: metav1.ObjectMeta{
-			Name:      kubeadmconstants.KubeadmConfigConfigMap,
-			Namespace: metav1.NamespaceSystem,
-		},
-		Data: map[string]string{
-			kubeadmconstants.ClusterStatusConfigMapKey: string(statusYaml),
-		},
-	})
-}

cmd/kubeadm/app/preflight/checks.go

@@ -900,6 +900,7 @@ func RunInitMasterChecks(execer utilsexec.Interface, cfg *kubeadmapi.InitConfigu
 		// Only do etcd related checks when no external endpoints were specified
 		checks = append(checks,
 			PortOpenCheck{port: kubeadmconstants.EtcdListenClientPort},
+			PortOpenCheck{port: kubeadmconstants.EtcdListenPeerPort},
 			DirAvailableCheck{Path: cfg.Etcd.Local.DataDir},
 		)
 	}

cmd/kubeadm/app/util/config/BUILD

@@ -25,6 +25,7 @@ go_library(
         "//cmd/kubeadm/app/util:go_default_library",
         "//pkg/util/node:go_default_library",
         "//staging/src/k8s.io/api/core/v1:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/api/errors:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
@@ -35,6 +36,7 @@ go_library(
         "//staging/src/k8s.io/client-go/util/cert:go_default_library",
         "//staging/src/k8s.io/cluster-bootstrap/token/util:go_default_library",
         "//vendor/github.com/golang/glog:go_default_library",
+        "//vendor/github.com/pkg/errors:go_default_library",
     ],
 )
 

cmd/kubeadm/app/util/config/cluster.go

@@ -18,13 +18,14 @@ package config
 
 import (
 	"crypto/x509"
-	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
 	"path/filepath"
 	"strings"
 
+	"github.com/pkg/errors"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/version"
@@ -196,12 +197,8 @@ func getNodeNameFromKubeletConfig(kubeconfigDir string) (string, error) {
 // getAPIEndpoint returns the APIEndpoint for the current node
 func getAPIEndpoint(data map[string]string, nodeName string, apiEndpoint *kubeadmapi.APIEndpoint) error {
 	// gets the ClusterStatus from kubeadm-config
-	clusterStatusData, ok := data[constants.ClusterStatusConfigMapKey]
-	if !ok {
-		return fmt.Errorf("unexpected error when reading kubeadm-config ConfigMap: %s key value pair missing", constants.ClusterStatusConfigMapKey)
-	}
-	clusterStatus := &kubeadmapi.ClusterStatus{}
-	if err := runtime.DecodeInto(kubeadmscheme.Codecs.UniversalDecoder(), []byte(clusterStatusData), clusterStatus); err != nil {
+	clusterStatus, err := unmarshalClusterStatus(data)
+	if err != nil {
 		return err
 	}
 
@@ -232,3 +229,34 @@ func getComponentConfigs(client clientset.Interface, clusterConfiguration *kubea
 	}
 	return nil
 }
+
+// GetClusterStatus returns the kubeadm cluster status read from the kubeadm-config ConfigMap
+func GetClusterStatus(client clientset.Interface) (*kubeadmapi.ClusterStatus, error) {
+	configMap, err := client.CoreV1().ConfigMaps(metav1.NamespaceSystem).Get(constants.KubeadmConfigConfigMap, metav1.GetOptions{})
+	if apierrors.IsNotFound(err) {
+		return &kubeadmapi.ClusterStatus{}, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	clusterStatus, err := unmarshalClusterStatus(configMap.Data)
+	if err != nil {
+		return nil, err
+	}
+
+	return clusterStatus, nil
+}
+
+func unmarshalClusterStatus(data map[string]string) (*kubeadmapi.ClusterStatus, error) {
+	clusterStatusData, ok := data[constants.ClusterStatusConfigMapKey]
+	if !ok {
+		return nil, errors.Errorf("unexpected error when reading kubeadm-config ConfigMap: %s key value pair missing", constants.ClusterStatusConfigMapKey)
+	}
+	clusterStatus := &kubeadmapi.ClusterStatus{}
+	if err := runtime.DecodeInto(kubeadmscheme.Codecs.UniversalDecoder(), []byte(clusterStatusData), clusterStatus); err != nil {
+		return nil, err
+	}
+
+	return clusterStatus, nil
+}

cmd/kubeadm/app/util/config/cluster_test.go

@@ -770,6 +770,94 @@ func TestGetInitConfigurationFromCluster(t *testing.T) {
 	}
 }
 
+func TestGetGetClusterStatus(t *testing.T) {
+	var tests = []struct {
+		name              string
+		configMaps        []fakeConfigMap
+		expectedEndpoints int
+		expectedError     bool
+	}{
+		{
+			name:              "invalid missing config map",
+			expectedEndpoints: 0,
+		},
+		{
+			name: "valid v1beta1",
+			configMaps: []fakeConfigMap{
+				{
+					name: kubeadmconstants.KubeadmConfigConfigMap,
+					data: map[string]string{
+						kubeadmconstants.ClusterStatusConfigMapKey: string(cfgFiles["ClusterStatus_v1beta1"]),
+					},
+				},
+			},
+			expectedEndpoints: 1,
+		},
+		{
+			name: "valid v1alpha3",
+			configMaps: []fakeConfigMap{
+				{
+					name: kubeadmconstants.KubeadmConfigConfigMap,
+					data: map[string]string{
+						kubeadmconstants.ClusterStatusConfigMapKey: string(cfgFiles["ClusterStatus_v1alpha3"]),
+					},
+				},
+			},
+			expectedEndpoints: 1,
+		},
+		{
+			name: "invalid missing ClusterStatusConfigMapKey in the config map",
+			configMaps: []fakeConfigMap{
+				{
+					name: kubeadmconstants.KubeadmConfigConfigMap,
+					data: map[string]string{},
+				},
+			},
+			expectedError: true,
+		},
+		{
+			name: "invalid wrong value in the config map",
+			configMaps: []fakeConfigMap{
+				{
+					name: kubeadmconstants.KubeadmConfigConfigMap,
+					data: map[string]string{
+						kubeadmconstants.ClusterStatusConfigMapKey: "not a kubeadm type",
+					},
+				},
+			},
+			expectedError: true,
+		},
+	}
+
+	for _, rt := range tests {
+		t.Run(rt.name, func(t *testing.T) {
+			client := clientsetfake.NewSimpleClientset()
+
+			for _, c := range rt.configMaps {
+				err := c.create(client)
+				if err != nil {
+					t.Errorf("couldn't create ConfigMap %s", c.name)
+					return
+				}
+			}
+
+			clusterStatus, err := GetClusterStatus(client)
+			if rt.expectedError != (err != nil) {
+				t.Errorf("unexpected return err from GetClusterStatus: %v", err)
+				return
+			}
+			if rt.expectedError {
+				return
+			}
+
+			// Test expected values in clusterStatus
+			if len(clusterStatus.APIEndpoints) != rt.expectedEndpoints {
+				t.Errorf("unexpected ClusterStatus return value")
+			}
+		})
+	}
+}
+
 type fakeConfigMap struct {
 	name string
 	data map[string]string

cmd/kubeadm/app/util/etcd/BUILD

@@ -8,9 +8,12 @@ go_library(
     deps = [
         "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
         "//cmd/kubeadm/app/constants:go_default_library",
+        "//cmd/kubeadm/app/util/config:go_default_library",
         "//cmd/kubeadm/app/util/staticpod:go_default_library",
+        "//staging/src/k8s.io/client-go/kubernetes:go_default_library",
         "//vendor/github.com/coreos/etcd/clientv3:go_default_library",
         "//vendor/github.com/coreos/etcd/pkg/transport:go_default_library",
+        "//vendor/github.com/golang/glog:go_default_library",
         "//vendor/github.com/pkg/errors:go_default_library",
     ],
 )

cmd/kubeadm/app/util/etcd/etcd.go

@@ -26,9 +26,12 @@ import (
 
 	"github.com/coreos/etcd/clientv3"
 	"github.com/coreos/etcd/pkg/transport"
+	"github.com/golang/glog"
 	"github.com/pkg/errors"
+	clientset "k8s.io/client-go/kubernetes"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
+	"k8s.io/kubernetes/cmd/kubeadm/app/util/config"
 	"k8s.io/kubernetes/cmd/kubeadm/app/util/staticpod"
 )
 
@@ -40,6 +43,8 @@ type ClusterInterrogator interface {
 	GetVersion() (string, error)
 	HasTLS() bool
 	WaitForClusterAvailable(delay time.Duration, retries int, retryInterval time.Duration) (bool, error)
+	Sync() error
+	AddMember(name string, peerAddrs string) ([]Member, error)
 }
 
 // Client provides connection parameters for an etcd cluster
@@ -125,6 +130,108 @@ func NewFromStaticPod(endpoints []string, manifestDir string, certificatesDir st
 	return New(endpoints, "", "", "")
 }
 
+// NewFromCluster creates an etcd client for the the etcd endpoints defined in the ClusterStatus value stored in
+// the kubeadm-config ConfigMap in kube-system namespace.
+// Once created, the client synchronizes client's endpoints with the known endpoints from the etcd membership API (reality check).
+func NewFromCluster(client clientset.Interface, certificatesDir string) (*Client, error) {
+	// Gets the cluster status
+	clusterStatus, err := config.GetClusterStatus(client)
+	if err != nil {
+		return nil, err
+	}
+
+	// Get the list of etcd endpoints from cluster status
+	endpoints := []string{}
+	for _, e := range clusterStatus.APIEndpoints {
+		endpoints = append(endpoints, fmt.Sprintf("https://%s:%d", e.AdvertiseAddress, constants.EtcdListenClientPort))
+	}
+	glog.V(1).Infof("etcd endpoints read from pods: %s", strings.Join(endpoints, ","))
+
+	// Creates an etcd client
+	etcdClient, err := New(
+		endpoints,
+		filepath.Join(certificatesDir, constants.EtcdCACertName),
+		filepath.Join(certificatesDir, constants.EtcdHealthcheckClientCertName),
+		filepath.Join(certificatesDir, constants.EtcdHealthcheckClientKeyName),
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	// synchronizes client's endpoints with the known endpoints from the etcd membership.
+	err = etcdClient.Sync()
+	if err != nil {
+		return nil, err
+	}
+
+	return etcdClient, nil
+}
+
+// Sync synchronizes client's endpoints with the known endpoints from the etcd membership.
+func (c Client) Sync() error {
+	cli, err := clientv3.New(clientv3.Config{
+		Endpoints:   c.Endpoints,
+		DialTimeout: 20 * time.Second,
+		TLS:         c.TLS,
+	})
+	if err != nil {
+		return err
+	}
+	defer cli.Close()
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	err = cli.Sync(ctx)
+	cancel()
+	if err != nil {
+		return err
+	}
+	glog.V(1).Infof("etcd endpoints read from etcd: %s", strings.Join(cli.Endpoints(), ","))
+
+	c.Endpoints = cli.Endpoints()
+	return nil
+}
+
+// Member struct defines an etcd member; it is used for avoiding to spread github.com/coreos/etcd dependency
+// across kubeadm codebase
+type Member struct {
+	Name    string
+	PeerURL string
+}
+
+// AddMember notifies an existing etcd cluster that a new member is joining
+func (c Client) AddMember(name string, peerAddrs string) ([]Member, error) {
+	cli, err := clientv3.New(clientv3.Config{
+		Endpoints:   c.Endpoints,
+		DialTimeout: 20 * time.Second,
+		TLS:         c.TLS,
+	})
+	if err != nil {
+		return nil, err
+	}
+	defer cli.Close()
+
+	// Adds a new member to the cluster
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	resp, err := cli.MemberAdd(ctx, []string{peerAddrs})
+	cancel()
+	if err != nil {
+		return nil, err
+	}
+
+	// Returns the updated list of etcd members
+	ret := []Member{}
+	for _, m := range resp.Members {
+		// fixes the entry for the joining member (that doesn't have a name set in the initialCluster returned by etcd)
+		if m.Name == "" {
+			ret = append(ret, Member{Name: name, PeerURL: m.PeerURLs[0]})
+		} else {
+			ret = append(ret, Member{Name: m.Name, PeerURL: m.PeerURLs[0]})
+		}
+	}
+
+	return ret, nil
+}
+
 // GetVersion returns the etcd version of the cluster.
 // An error is returned if the version of all endpoints do not match
 func (c Client) GetVersion() (string, error) {