ZooKeeper ACLs Best Practices
As more and more components begin to rely on ZooKeeper within a Hadoop cluster, there are various permissions that need to be maintained to ensure the integrity and security of the znodes. These permissions are different from component to component. You must follow the required steps for tightening the ZooKeeper ACLs or permissions when provisioning a secure cluster as a best practices guideline.
Some components only use ZooKeeper when they are running in their component specific HA mode. Others have separate secure and unsecure ACLs defined and switch between which to enforce based on the component knowledge of whether the cluster is secured or not.
In general, ACLs are pretty open and assume an unsecure cluster by default. These permissions need to be hardened for secure clusters in order to avoid inappropriate access or modification of this critical platform state.