Apache ZooKeeper¶

The zookeeper probe monitors an Apache ZooKeeper node via the mntr four-letter command over raw TCP, reporting request latency, packet counts, connection counts, znode and watch counts, file descriptor usage and ensemble state (leader/follower/observer).

Quick start¶

probes:
  - name: zookeeper
    type: zookeeper
    params:
      host: localhost
      port: 2181

Parameters¶

Parameter	Default	Description
`host`	`localhost`	ZooKeeper node hostname or IP
`port`	`2181`	ZooKeeper client port

Metrics¶

Metric	Unit	Description
`senhub.zookeeper.up`	1	1 when the node answered the `mntr` command
`zookeeper.latency.avg`	ms	Average request processing latency (`zk_avg_latency`)
`zookeeper.latency.max`	ms	Maximum request processing latency
`zookeeper.connections.count`	{connection}	Current client connections
`zookeeper.packets.received`	{packet}	Packets received since start
`zookeeper.packets.sent`	{packet}	Packets sent since start
`zookeeper.znodes.count`	{znode}	Number of znodes in the data tree
`zookeeper.watches.count`	{watch}	Number of active watches
`zookeeper.file_descriptors.open`	{fd}	Open file descriptors
`zookeeper.leader_elections`	{election}	Leader elections triggered (leader nodes only)
`zookeeper.pending_syncs`	{sync}	Pending sync operations (leader only)

Operational notes¶

The mntr four-letter command must be enabled in zoo.cfg: 4lw.commands.whitelist=mntr (required since ZooKeeper 3.5).
Leader-only metrics (leader_elections, pending_syncs) are only emitted by the ensemble leader; follower nodes emit zero or omit them.
For multi-node ensembles, configure one probe instance per node to monitor the ensemble comprehensively.