搭建etcd集群时，报错etcd: request cluster ID mismatch错误解决，只适用于新建etcd集群或无数据集群

在搭建etcd时集群时，碰到集群无法正常启动，查看日志可以发现：

Mar 01 00:16:48 k8s-master etcd[2118]: request cluster ID mismatch (got 1b52d892f8086ec1 want 5b2749c5cdc7697b)
Mar 01 00:16:48 k8s-master etcd[2118]: request cluster ID mismatch (got 1b52d892f8086ec1 want 5b2749c5cdc7697b)
Mar 01 00:16:48 k8s-master etcd[2118]: request cluster ID mismatch (got 1b52d892f8086ec1 want 5b2749c5cdc7697b)
Mar 01 00:16:48 k8s-master etcd[2118]: request cluster ID mismatch (got 1b52d892f8086ec1 want 5b2749c5cdc7697b)
Mar 01 00:16:48 k8s-master etcd[2118]: request sent was ignored (cluster ID mismatch: peer[c0236cc262568b7d]=1b52d892f8086ec1, local=5
Mar 01 00:16:48 k8s-master etcd[2118]: request sent was ignored (cluster ID mismatch: peer[c0236cc262568b7d]=1b52d892f8086ec1, local=5
Mar 01 00:16:48 k8s-master etcd[2118]: request cluster ID mismatch (got 1b52d892f8086ec1 want 5b2749c5cdc7697b)
Mar 01 00:16:48 k8s-master etcd[2118]: request cluster ID mismatch (got 1b52d892f8086ec1 want 5b2749c5cdc7697b)
Mar 01 00:16:48 k8s-master etcd[2118]: request cluster ID mismatch (got 1b52d892f8086ec1 want 5b2749c5cdc7697b)
Mar 01 00:16:48 k8s-master etcd[2118]: request cluster ID mismatch (got 1b52d892f8086ec1 want 5b2749c5cdc7697b)

原因分析： 通过日志，可以得知，故障的原因为集群的id匹配不上，有可能时搭建过程中启动过某个节点等原因导致
解决：
注意：此方法仅用于新搭建的集群进行解决，原有有数据的集群不能这样做！！

1. 通过配置文件，或者启动脚本，找到etcd存放数据的目录
   
2. 对所有集群节点该目录下的数据进行删除，删除前需要先停止所有etcd
3. systemctl daemon-reload && systemctl start etcd
   这时候，新搭建的集群就能正常启动了