It's common for server stacks to already partially exist; often using components we don't have the privilege of choosing. Servers and related software can be around for years before we adapt them to our needs. Thus it's possible an infrastructure department already uses a distributed key-value storage system like etcd for its own purposes.
ZooKeeper is one of these alternative key-value storage layers. Patroni is fully capable of utilizing this instead of etcd, provided we make some changes to how it is configured.
Let's leverage an existing ZooKeeper installation to our advantage!
Please note that installing ZooKeeper itself is beyond the scope of this recipe. The intention here is to make changes to Patroni that make it compatible with an existing ZooKeeper installation. This can happen when an infrastructure already incorporates ZooKeeper, allowing us to leverage it as well.