Kafka survival guide

cli.md

Get committed offets on Kafka consumer

The guide explains how to inspect consumer using Kafka CLI.

Find running Kafka container:

> docker ps | grep kafka

Enter your Kafka (docker) container:

> docker exec -it <your-kafka-container> bash

Install Kafka CLI (only once)

Verify Dependencies

Verify Java is installed

> java -version

# openjdk version "21.0.11" 2026-04-21 LTS
# OpenJDK Runtime Environment Temurin-21.0.11+10 (build 21.0.11+10-LTS)
# OpenJDK 64-Bit Server VM Temurin-21.0.11+10 (build 21.0.11+10-LTS, mixed mode, sharing)

Wget (installation tool)

> which wget
# /usr/bin/wget

Tar (unzip tool)

> which tar
# /bin/tar

Install CLI:

Enter tmp directory to be able to download things

> cd /tmp

Download Kafka installer

> wget https://archive.apache.org/dist/kafka/3.7.0/kafka_2.13-3.7.0.tgz

Unzip files:

> tar -xvf kafka_2.13-3.7.0.tgz

Enter unzipped directory:

> cd kafka_2.13-3.7.0/bin

Kafka Groups: commands to run

List active groups (within the Broker):

> ./kafka-consumer-groups.sh --bootstrap-server localhost:9092 --list

# group1
# group2
# group3

Inspect your group:

> ./kafka-consumer-groups.sh --bootstrap-server localhost:9092 --describe --group <your-group>

$:/tmp/kafka_2.13-3.7.0/bin$ ./kafka-consumer-groups.sh --bootstrap-server localhost:9092 --describe --group red-group

GROUP           TOPIC           PARTITION  CURRENT-OFFSET  LOG-END-OFFSET  LAG             CONSUMER-ID                                      HOST            CLIENT-ID
red-group       first-topic     0          10              10              0               my-node-app-48dcd40e-4bec-4d71-92d0-6931d3586f8b /172.18.0.1     my-node-app

Inspect all groups:

> ./kafka-consumer-groups.sh --bootstrap-server localhost:9092 --describe --all-groups

kafkajs-admin.js

const { Kafka, logLevel  } = require('kafkajs');

const kafka = new Kafka({
    clientId: 'my-node-app',
    brokers: ['localhost:9092'],
    logLevel: logLevel.NOTHING,
    retry: {
      initialRetryTime: 300,
      retries: 8
    }
  });

const fetchOffsets = async () => {

  const admin = kafka.admin();
  await admin.connect();

  const offsets = await admin.fetchTopicOffsets('first-topic');
  console.log(offsets);

  await admin.disconnect();

};

fetchOffsets().catch(console.error);