etcdctl --endpoints=localhost:12379 lease grant 30
etcdctl --endpoints=localhost:12379 lease list
etcdctl --endpoints=localhost:12379 --lease 1cf77c6926d4620e put /a b
etcdctl --endpoints=localhost:12379 get --prefix /
etcdctl --endpoints=localhost:12379 lease keep-alive 1cf77c6926d4620e