Upgrading from 2.0.x could be a shaky path; in fact etcd devs only guarantee a flawless transition if the upgrade is from 2.1:

https://github.com/coreos/etcd/blob/release-2.2/Documentation/upgrade_2_2.md

we should thoroughly test the upgrade path from our current version to 2.2 and maybe come up with alternative approaches like doing a dump and load with https://github.com/lavagetto/etcddump