[root@k8s-master01 ssl]# etcdctl member list   
client: etcd cluster is unavailable or misconfigured; error #0: x509: certificate signed by unknown authority
; error #1: x509: certificate signed by unknown authority
; error #2: x509: certificate signed by unknown authority

etcdctl工具是一个可以对etcd数据进行管理的命令行工具，这个工具在两个不同的etcd版本下的行为方式也完全不同。

export ETCDCTL_API=2

export ETCDCTL_API=3

解决方法：

[root@k8s-master01 ssl]# export ETCDCTL_API=3

[root@k8s-master01 ssl]# systemctl restart etcd
[root@k8s-master01 ssl]# etcdctl member list   
4b28ead506078a9, started, k8s-master01, https://172.18.98.21:2380, https://172.18.98.21:2379
298eff4fdb961547, started, k8s-master02, https://172.18.98.22:2380, https://172.18.98.22:2379
450977bc449bdf82, started, k8s-master03, https://172.18.98.23:2380, https://172.18.98.23:2379