There is no specific reason to start with ZooKeeper, nor with ClickHouse Keeper, if you want to use another distributed consensus system. But: every such syste

There is no specific reason to start with ZooKeeper, nor with ClickHouse Keeper, if you want to use another distributed consensus system. But: every such system is slightly different in the data model and the set of available primitives. It's very hard to build a distributed system correctly, even relying on ZooKeeper/Etcd/FoundationDB. For example, when I hear "distributed lock," I know that there is 90% chance there is a bug (distributed lock can be safely used if every transaction made under a lock also atomically tests that the lock still holds). So, if there is an existing system heavily relying on one distributed consensus implementation, it's very hard to switch to another. The main value of ClickHouse Keeper is its compatibility with ZooKeeper - it uses the same data model and wire protocol.