CODEWITHSUNDEEP
apache-kafka
Suhas Chikkanna
Suhas Chikkanna

Reputation: 1510

How to know the broker that is the active controller?

Other than using JMX is there any other way to know, whether a broker is an ActiveController?

I know that the cluster generates a metric kafka.controller:type=KafkaController,name=ActiveControllerCount, but I cannot find which broker is the active controller.

Is it necessary to write a JMX client to know it or is there another (better?) way?

Upvotes: 13

Views: 18911

Answers (4)

DieterDP
DieterDP

Reputation: 4347

Starting from Kafka 3.3.1, Kafka uses KRaft instead of ZooKeeper to elect/manage the active controller. See this question on how to find the active controller in such a cluster.

Upvotes: 2

Paul Robu
Paul Robu

Reputation: 122

Also by calling zookeeper-shell.sh twice, we can get directly the broker name that is the active controller, instead of the broker id.

Example for a zookeeper instance running on localhost:

/opt/kafka/bin/zookeeper-shell.sh localhost get /brokers/ids/$(/opt/kafka/bin/zookeeper-shell.sh localhost get /controller|tail -1|jq .brokerid)|tail -1|jq .endpoints[]

Upvotes: 1

Mickael Maison
Mickael Maison

Reputation: 26865

You can find the active controller using the zookeeper-shell tool as follows:

./bin/zookeeper-shell.sh [ZK_IP] get /controller

Upvotes: 25

Milos Pajic
Milos Pajic

Reputation: 336

Perhaps easier way, since you don't need to have kafka and it's zookeeper-shell.sh, is using command line to connect to zookeeper's client port with: 

nc [zookeeper_ip] [zookeeper_port]

or

telnet [zookeeper_ip] [zookeeper_port]

and then executing 

dump

It will print sessions with ephemeral nodes and one can see which broker is a controller by finding session that contains /controller path

For example, a dump result like this:

Sessions with Ephemerals (3):
0x266542cfaa90000:
    /brokers/ids/1
0x166542cfe670001:
    /brokers/ids/3
0x166542cfe670000:
    /controller
    /brokers/ids/2

means that controller is a broker whose broker_id is 2.

Upvotes: 10

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