kubeadm: Use internal etcd client through an interface

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

@@ -66,27 +66,69 @@ type ClusterInterrogator interface {
 	RemoveMember(id uint64) ([]Member, error)
 }
 
+type etcdClient interface {
+	// Close shuts down the client's etcd connections.
+	Close() error
+
+	// Endpoints lists the registered endpoints for the client.
+	Endpoints() []string
+
+	// MemberList lists the current cluster membership.
+	MemberList(ctx context.Context) (*clientv3.MemberListResponse, error)
+
+	// MemberAdd adds a new member into the cluster.
+	MemberAdd(ctx context.Context, peerAddrs []string) (*clientv3.MemberAddResponse, error)
+
+	// MemberAddAsLearner adds a new learner member into the cluster.
+	MemberAddAsLearner(ctx context.Context, peerAddrs []string) (*clientv3.MemberAddResponse, error)
+
+	// MemberRemove removes an existing member from the cluster.
+	MemberRemove(ctx context.Context, id uint64) (*clientv3.MemberRemoveResponse, error)
+
+	// MemberPromote promotes a member from raft learner (non-voting) to raft voting member.
+	MemberPromote(ctx context.Context, id uint64) (*clientv3.MemberPromoteResponse, error)
+
+	// Status gets the status of the endpoint.
+	Status(ctx context.Context, endpoint string) (*clientv3.StatusResponse, error)
+
+	// Sync synchronizes client's endpoints with the known endpoints from the etcd membership.
+	Sync(ctx context.Context) error
+}
+
 // Client provides connection parameters for an etcd cluster
 type Client struct {
 	Endpoints []string
-	TLS       *tls.Config
+
+	newEtcdClient func(endpoints []string) (etcdClient, error)
 }
 
 // New creates a new EtcdCluster client
 func New(endpoints []string, ca, cert, key string) (*Client, error) {
 	client := Client{Endpoints: endpoints}
 
+	var err error
+	var tlsConfig *tls.Config
 	if ca != "" || cert != "" || key != "" {
 		tlsInfo := transport.TLSInfo{
 			CertFile:      cert,
 			KeyFile:       key,
 			TrustedCAFile: ca,
 		}
-		tlsConfig, err := tlsInfo.ClientConfig()
+		tlsConfig, err = tlsInfo.ClientConfig()
 		if err != nil {
 			return nil, err
 		}
-		client.TLS = tlsConfig
+	}
+
+	client.newEtcdClient = func(endpoints []string) (etcdClient, error) {
+		return clientv3.New(clientv3.Config{
+			Endpoints:   endpoints,
+			DialTimeout: etcdTimeout,
+			DialOptions: []grpc.DialOption{
+				grpc.WithBlock(), // block until the underlying connection is up
+			},
+			TLS: tlsConfig,
+		})
 	}
 
 	return &client, nil
@@ -192,24 +234,16 @@ func getRawEtcdEndpointsFromPodAnnotationWithoutRetry(client clientset.Interface
 // Sync synchronizes client's endpoints with the known endpoints from the etcd membership.
 func (c *Client) Sync() error {
 	// Syncs the list of endpoints
-	var cli *clientv3.Client
+	var cli etcdClient
 	var lastError error
 	err := wait.ExponentialBackoff(etcdBackoff, func() (bool, error) {
 		var err error
-		cli, err = clientv3.New(clientv3.Config{
+		cli, err = c.newEtcdClient(c.Endpoints)
-			Endpoints:   c.Endpoints,
-			DialTimeout: etcdTimeout,
-			DialOptions: []grpc.DialOption{
-				grpc.WithBlock(), // block until the underlying connection is up
-			},
-			TLS: c.TLS,
-		})
 		if err != nil {
 			lastError = err
 			return false, nil
 		}
 		defer cli.Close()
-
 		ctx, cancel := context.WithTimeout(context.Background(), etcdTimeout)
 		err = cli.Sync(ctx)
 		cancel()
@@ -241,14 +275,7 @@ func (c *Client) listMembers() (*clientv3.MemberListResponse, error) {
 	var lastError error
 	var resp *clientv3.MemberListResponse
 	err := wait.ExponentialBackoff(etcdBackoff, func() (bool, error) {
-		cli, err := clientv3.New(clientv3.Config{
+		cli, err := c.newEtcdClient(c.Endpoints)
-			Endpoints:   c.Endpoints,
-			DialTimeout: etcdTimeout,
-			DialOptions: []grpc.DialOption{
-				grpc.WithBlock(), // block until the underlying connection is up
-			},
-			TLS: c.TLS,
-		})
 		if err != nil {
 			lastError = err
 			return false, nil
@@ -306,14 +333,7 @@ func (c *Client) RemoveMember(id uint64) ([]Member, error) {
 	var lastError error
 	var resp *clientv3.MemberRemoveResponse
 	err := wait.ExponentialBackoff(etcdBackoff, func() (bool, error) {
-		cli, err := clientv3.New(clientv3.Config{
+		cli, err := c.newEtcdClient(c.Endpoints)
-			Endpoints:   c.Endpoints,
-			DialTimeout: etcdTimeout,
-			DialOptions: []grpc.DialOption{
-				grpc.WithBlock(), // block until the underlying connection is up
-			},
-			TLS: c.TLS,
-		})
 		if err != nil {
 			lastError = err
 			return false, nil
@@ -365,14 +385,7 @@ func (c *Client) addMember(name string, peerAddrs string, isLearner bool) ([]Mem
 		return nil, errors.Wrapf(err, "error parsing peer address %s", peerAddrs)
 	}
 
-	cli, err := clientv3.New(clientv3.Config{
+	cli, err := c.newEtcdClient(c.Endpoints)
-		Endpoints:   c.Endpoints,
-		DialTimeout: etcdTimeout,
-		DialOptions: []grpc.DialOption{
-			grpc.WithBlock(), // block until the underlying connection is up
-		},
-		TLS: c.TLS,
-	})
 	if err != nil {
 		return nil, err
 	}
@@ -482,14 +495,7 @@ func (c *Client) MemberPromote(learnerID uint64) error {
 	}
 
 	klog.V(1).Infof("[etcd] Promoting a learner as a voting member: %016x", learnerID)
-	cli, err := clientv3.New(clientv3.Config{
+	cli, err := c.newEtcdClient(c.Endpoints)
-		Endpoints:   c.Endpoints,
-		DialTimeout: etcdTimeout,
-		DialOptions: []grpc.DialOption{
-			grpc.WithBlock(), // block until the underlying connection is up
-		},
-		TLS: c.TLS,
-	})
 	if err != nil {
 		return err
 	}
@@ -537,14 +543,7 @@ func (c *Client) getClusterStatus() (map[string]*clientv3.StatusResponse, error)
 		var lastError error
 		var resp *clientv3.StatusResponse
 		err := wait.ExponentialBackoff(etcdBackoff, func() (bool, error) {
-			cli, err := clientv3.New(clientv3.Config{
+			cli, err := c.newEtcdClient(c.Endpoints)
-				Endpoints:   c.Endpoints,
-				DialTimeout: etcdTimeout,
-				DialOptions: []grpc.DialOption{
-					grpc.WithBlock(), // block until the underlying connection is up
-				},
-				TLS: c.TLS,
-			})
 			if err != nil {
 				lastError = err
 				return false, nil