Comment 5 for bug 1759597

The best fit would be etcd3 if it had support for leadership methods because Designate uses them in the coordination code.

leader_methods = [
    'watch_elected_as_leader',
    'unwatch_elected_as_leader',
    'stand_down_group_leader',
    'get_leader',
]

As of Queens only Memcached, Redis, Zake and Zookeeper have that supported:
https://github.com/openstack/tooz/blob/stable/queens/tools/compat-matrix.py#L104-L119