kafkacat

kafkacat is a generic non-JVM producer and consumer for Apache Kafka >=0.8, think of it as a netcat for Kafka.

In producer mode kafkacat reads messages from stdin, delimited with a configurable delimeter (-D, defaults to newline), and produces them to the provided Kafka cluster (-b), topic (-t) and partition (-p).

In consumer mode kafkacat reads messages from a topic and partition and prints them to stdout using the configured message delimiter.

There's also support for the Kafka >=0.9 high-level balanced consumer, use the -G <group> switch and provide a list of topics to join the group.

kafkacat also features a Metadata list (-L) mode to display the current state of the Kafka cluster and its topics and partitions.

kafkacat is fast and lightweight; statically linked it is no more than 150Kb.

Install

On recent enough Debian systems:

apt-get install kafkacat

And on Mac OS X with homebrew installed:

brew install kafkacat

Otherwise follow directions below.

Requirements

librdkafka - https://github.com/edenhill/librdkafka
libyajl (for JSON support, optional)

On Ubuntu or Debian: sudo apt-get install librdkafka-dev libyajl-dev

Build

./configure <usual-configure-options>
make
sudo make install

Quick build

The bootstrap.sh build script will download and build the required dependencies, providing a quick and easy means of building kafkacat. Internet connectivity and wget/curl is required by this script. The resulting kafkacat binary will be linked statically to avoid runtime dependencies. NOTE: Requires curl and cmake (for yajl) to be installed.

./bootstrap.sh

Examples

High-level balanced KafkaConsumer: subscribe to topic1 and topic2 (requires broker >=0.9.0 and librdkafka version >=0.9.1)

$ kafkacat -b mybroker -G mygroup topic1 topic2

Read messages from stdin, produce to 'syslog' topic with snappy compression

$ tail -f /var/log/syslog | kafkacat -b mybroker -t syslog -z snappy

Read messages from Kafka 'syslog' topic, print to stdout

$ kafkacat -b mybroker -t syslog

Produce messages from file (one file is one message)

$ kafkacat -P -b mybroker -t filedrop -p 0 myfile1.bin /etc/motd thirdfile.tgz

Read the last 2000 messages from 'syslog' topic, then exit

$ kafkacat -C -b mybroker -t syslog -p 0 -o -2000 -e

Consume from all partitions from 'syslog' topic

$ kafkacat -C -b mybroker -t syslog

Output consumed messages in JSON envelope:

$ kafkacat -b mybroker -t syslog -J

Output consumed messages according to format string:

$ kafkacat -b mybroker -t syslog -f 'Topic %t[%p], offset: %o, key: %k, payload: %S bytes: %s\n'

Read the last 100 messages from topic 'syslog' with librdkafka configuration parameter 'broker.version.fallback' set to '0.8.2.1' :

$ kafkacat -C -b mybroker -X broker.version.fallback=0.8.2.1 -t syslog -p 0 -o -100 -e

Metadata listing

$ kafkacat -L -b mybroker
Metadata for all topics (from broker 1: mybroker:9092/1):
 3 brokers:
  broker 1 at mybroker:9092
  broker 2 at mybrokertoo:9092
  broker 3 at thirdbroker:9092
 16 topics:
  topic "syslog" with 3 partitions:
    partition 0, leader 3, replicas: 1,2,3, isrs: 1,2,3
    partition 1, leader 1, replicas: 1,2,3, isrs: 1,2,3
    partition 2, leader 1, replicas: 1,2, isrs: 1,2
  topic "rdkafkatest1_auto_49f744a4327b1b1e" with 2 partitions:
    partition 0, leader 3, replicas: 3, isrs: 3
    partition 1, leader 1, replicas: 1, isrs: 1
  topic "rdkafkatest1_auto_e02f58f2c581cba" with 2 partitions:
    partition 0, leader 3, replicas: 3, isrs: 3
    partition 1, leader 1, replicas: 1, isrs: 1
  ....

JSON metadata listing

$ kafkacat -b mybroker -L -J

Pretty-printed JSON metadata listing

$ kafkacat -b mybroker -L -J | jq .

Query offset(s) by timestamp(s)