kubeadm: Remove etcd member from the etcd cluster when reset the control plane node

cmd/kubeadm/app/cmd/BUILD

@@ -40,6 +40,7 @@ go_library(
         "//cmd/kubeadm/app/images:go_default_library",
         "//cmd/kubeadm/app/phases/bootstraptoken/node:go_default_library",
         "//cmd/kubeadm/app/phases/certs:go_default_library",
+        "//cmd/kubeadm/app/phases/etcd:go_default_library",
         "//cmd/kubeadm/app/phases/kubeconfig:go_default_library",
         "//cmd/kubeadm/app/phases/uploadconfig:go_default_library",
         "//cmd/kubeadm/app/preflight:go_default_library",

cmd/kubeadm/app/cmd/reset.go

@@ -36,6 +36,7 @@ import (
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
 	cmdutil "k8s.io/kubernetes/cmd/kubeadm/app/cmd/util"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
+	etcdphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/etcd"
 	"k8s.io/kubernetes/cmd/kubeadm/app/preflight"
 	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
 	configutil "k8s.io/kubernetes/cmd/kubeadm/app/util/config"
@@ -139,6 +140,9 @@ func (r *Reset) Run(out io.Writer, client clientset.Interface) error {
 	etcdDataDir, err := getEtcdDataDir(etcdManifestPath, client)
 	if err == nil {
 		dirsToClean = append(dirsToClean, etcdDataDir)
+		if err := removeEtcdMember(client); err != nil {
+			klog.Warningf("[reset] failed to remove etcd member: %v\n.Please manually remove this etcd member using etcdctl", err)
+		}
 	} else {
 		fmt.Println("[reset] no etcd config found. Assuming external etcd")
 		fmt.Println("[reset] please manually reset etcd to prevent further issues")
@@ -205,6 +209,14 @@ func (r *Reset) Run(out io.Writer, client clientset.Interface) error {
 	return nil
 }
 
+func removeEtcdMember(client clientset.Interface) error {
+	cfg, err := configutil.FetchInitConfigurationFromCluster(client, os.Stdout, "reset", false)
+	if err != nil {
+		return err
+	}
+	return etcdphase.RemoveStackedEtcdMemberFromCluster(client, cfg)
+}
+
 func getEtcdDataDir(manifestPath string, client clientset.Interface) (string, error) {
 	const etcdVolumeName = "etcd-data"
 	var dataDir string

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

@@ -81,6 +81,35 @@ func CheckLocalEtcdClusterStatus(client clientset.Interface, cfg *kubeadmapi.Clu
 	return nil
 }
 
+// RemoveStackedEtcdMemberFromCluster will remove a local etcd member from etcd cluster,
+// when reset the control plane node.
+func RemoveStackedEtcdMemberFromCluster(client clientset.Interface, cfg *kubeadmapi.InitConfiguration) error {
+	// creates an etcd client that connects to all the local/stacked etcd members
+	klog.V(1).Info("[etcd] 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 removing member
+	etcdPeerAddress := etcdutil.GetPeerURL(&cfg.LocalAPIEndpoint)
+
+	klog.V(2).Infof("[etcd] get the member id from peer: %s", etcdPeerAddress)
+	id, err := etcdClient.GetMemberID(etcdPeerAddress)
+	if err != nil {
+		return err
+	}
+
+	klog.V(1).Infof("[etcd] removing etcd member: %s, id: %d", etcdPeerAddress, id)
+	members, err := etcdClient.RemoveMember(id)
+	if err != nil {
+		return err
+	}
+	klog.V(1).Infof("[etcd] Updated etcd member list: %v", members)
+
+	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.

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

@@ -113,6 +113,14 @@ func (f fakeEtcdClient) AddMember(name string, peerAddrs string) ([]etcdutil.Mem
 	return []etcdutil.Member{}, nil
 }
 
+func (f fakeEtcdClient) GetMemberID(peerURL string) (uint64, error) {
+	return 0, nil
+}
+
+func (f fakeEtcdClient) RemoveMember(id uint64) ([]etcdutil.Member, error) {
+	return []etcdutil.Member{}, nil
+}
+
 func TestGetAvailableUpgrades(t *testing.T) {
 	etcdClient := fakeEtcdClient{}
 	tests := []struct {

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

@@ -256,6 +256,14 @@ func (c fakeTLSEtcdClient) AddMember(name string, peerAddrs string) ([]etcdutil.
 	return []etcdutil.Member{}, nil
 }
 
+func (c fakeTLSEtcdClient) GetMemberID(peerURL string) (uint64, error) {
+	return 0, nil
+}
+
+func (c fakeTLSEtcdClient) RemoveMember(id uint64) ([]etcdutil.Member, error) {
+	return []etcdutil.Member{}, nil
+}
+
 type fakePodManifestEtcdClient struct{ ManifestDir, CertificatesDir string }
 
 func (c fakePodManifestEtcdClient) ClusterAvailable() (bool, error) { return true, nil }
@@ -297,6 +305,14 @@ func (c fakePodManifestEtcdClient) AddMember(name string, peerAddrs string) ([]e
 	return []etcdutil.Member{}, nil
 }
 
+func (c fakePodManifestEtcdClient) GetMemberID(peerURL string) (uint64, error) {
+	return 0, nil
+}
+
+func (c fakePodManifestEtcdClient) RemoveMember(id uint64) ([]etcdutil.Member, error) {
+	return []etcdutil.Member{}, nil
+}
+
 func TestStaticPodControlPlane(t *testing.T) {
 	tests := []struct {
 		description          string

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

@@ -46,6 +46,8 @@ type ClusterInterrogator interface {
 	WaitForClusterAvailable(retries int, retryInterval time.Duration) (bool, error)
 	Sync() error
 	AddMember(name string, peerAddrs string) ([]Member, error)
+	GetMemberID(peerURL string) (uint64, error)
+	RemoveMember(id uint64) ([]Member, error)
 }
 
 // Client provides connection parameters for an etcd cluster
@@ -146,6 +148,62 @@ type Member struct {
 	PeerURL string
 }
 
+// GetMemberID returns the member ID of the given peer URL
+func (c Client) GetMemberID(peerURL string) (uint64, error) {
+	cli, err := clientv3.New(clientv3.Config{
+		Endpoints:   c.Endpoints,
+		DialTimeout: 30 * time.Second,
+		TLS:         c.TLS,
+	})
+	if err != nil {
+		return 0, err
+	}
+	defer cli.Close()
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	resp, err := cli.MemberList(ctx)
+	cancel()
+	if err != nil {
+		return 0, err
+	}
+
+	for _, member := range resp.Members {
+		if member.GetPeerURLs()[0] == peerURL {
+			return member.GetID(), nil
+		}
+	}
+	return 0, nil
+}
+
+// RemoveMember notifies an etcd cluster to remove an existing member
+func (c Client) RemoveMember(id uint64) ([]Member, error) {
+	cli, err := clientv3.New(clientv3.Config{
+		Endpoints:   c.Endpoints,
+		DialTimeout: 30 * time.Second,
+		TLS:         c.TLS,
+	})
+	if err != nil {
+		return nil, err
+	}
+	defer cli.Close()
+
+	// Remove an existing member from the cluster
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	resp, err := cli.MemberRemove(ctx, id)
+	cancel()
+	if err != nil {
+		return nil, err
+	}
+
+	// Returns the updated list of etcd members
+	ret := []Member{}
+	for _, m := range resp.Members {
+		ret = append(ret, Member{Name: m.Name, PeerURL: m.PeerURLs[0]})
+	}
+
+	return ret, nil
+}
+
 // AddMember notifies an existing etcd cluster that a new member is joining
 func (c *Client) AddMember(name string, peerAddrs string) ([]Member, error) {
 	// Parse the peer address, required to add the client URL later to the list