kubeadm: check whether the peer URL for the added etcd member already exists when the MemberAddAsLearner/MemberAdd fails

Author: SataQiu

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

@@ -421,29 +421,19 @@ func (c *Client) addMember(name string, peerAddrs string, isLearner bool) ([]Mem
 	var (
 		lastError   error
 		respMembers []*etcdserverpb.Member
-		learnerID   uint64
 		resp        *clientv3.MemberAddResponse
 	)
 	err = wait.PollUntilContextTimeout(context.Background(), constants.EtcdAPICallRetryInterval, constants.EtcdAPICallTimeout,
 		true, func(_ context.Context) (bool, error) {
 			ctx, cancel := context.WithTimeout(context.Background(), etcdTimeout)
 			defer cancel()
 			if isLearner {
-				// if learnerID is set, it means the etcd member is already added successfully.
-				if learnerID == 0 {
-					klog.V(1).Info("[etcd] Adding etcd member as learner")
-					resp, err = cli.MemberAddAsLearner(ctx, []string{peerAddrs})
-					if err != nil {
-						lastError = err
-						return false, nil
-					}
-					learnerID = resp.Member.ID
-				}
-				respMembers = resp.Members
-				return true, nil
+				klog.V(1).Infof("[etcd] Adding etcd member %q as learner", peerAddrs)
+				resp, err = cli.MemberAddAsLearner(ctx, []string{peerAddrs})
+			} else {
+				klog.V(1).Infof("[etcd] Adding etcd member %q", peerAddrs)
+				resp, err = cli.MemberAdd(ctx, []string{peerAddrs})
 			}
-
-			resp, err = cli.MemberAdd(ctx, []string{peerAddrs})
 			if err == nil {
 				respMembers = resp.Members
 				return true, nil