etcd upgrade

etcd 2.3升級到3.0， v2數據轉v3

主：

systemctl stop etcd
etcdctl backup --data-dir=/home/data --backup-dir=/home/etcd20181217

恢復:
1、複製數據，啓動etcd

cp -r etcd20181217 /var/lib/etcd
etcd --data-dir=/var/lib/etcd --force-new-cluster

2、v2轉v3

pkill etcd
export ETCDCTL_API=3
etcdctl migrate --data-dir /var/lib/etcd
systemctl start etcd
etcdctl get / --prefix --keys-only

已經顯示數據