For AI agents: the complete documentation index is available at /llms.txt, the full documentation bundle is available at /llms-full.txt, and this page is available as Markdown at /docs/databases/zookeeper.md.
Ivory

    ZooKeeper

    A ZooKeeper ensemble — the coordination service ClickHouse replicates through, and a store other HA tools can use too. ZooKeeper elects its leader by itself, so Ivory watches it rather than operating it.

    Stage: BETA

    At a glance

    • Cluster side — ZooKeeper's four-letter-word commands (mntr, conf) on the client port, used as both Keeper and Database port (2181)
    • Keeper credentials — none; the four-letter words have no authentication
    • Replication — one leader, followers and observers
    • Lag — not measured; ZooKeeper does not report it per follower

    How Ivory reads the cluster

    • Members — the server.N lines of the node's configuration, when they carry a client port (…;2181). The single-host template's lines do not, so there each node shows only itself.
    • Cluster identity — each node reports the ensemble it is configured into, so a node from another ensemble is flagged.
    • Roles — leader and standalone are the leader, follower and observer are replicas.
    • Also shown — the ZooKeeper version, the number of znodes and connections, and the server state when it is neither leader nor follower.
    • Warnings — followers not in sync with the leader, a server not serving requests, and a configuration Ivory could not read.

    ZooKeeper only answers commands on its whitelist, so add at least mntr and conf to 4lw.commands.whitelist.

    Operations

    • View the configuration (conf)

    Leader election is automatic and cannot be triggered by hand, so nothing else is offered.

    Query console

    A znode console: ls, get, create, set, delete and exists, plus the mntr, srvr, stat, ruok and conf commands. Database credentials, if given, are used as digest authentication. Saved queries include the root children, the ensemble configuration and the znodes Patroni and ClickHouse keep.

    Deploying

    Both templates run the official zookeeper:3.9 image with the four-letter words Ivory needs whitelisted.

    • ZooKeeper (Multi Host) — three nodes zookeeper1–zookeeper3, one per machine, client port 2181 (quorum 2888, election 3888). Server ids are 1–3 in order and the server list names 10.0.0.1–10.0.0.3; replace the addresses and keep the order.
    • ZooKeeper (Single Host) — all three on one machine on client ports 2181–2183. It is what the ClickHouse single-host template points at.

    See Deployment.