kafkacat

command-line Kafka producer and consumer

TLDR

Produce messages

$ echo "[message]" | kafkacat -P -b [localhost:9092] -t [topic]

Consume messages

$ kafkacat -C -b [localhost:9092] -t [topic]

Consume from beginning

$ kafkacat -C -b [localhost:9092] -t [topic] -o beginning

List topics

$ kafkacat -L -b [localhost:9092]

Produce from file

$ kafkacat -P -b [localhost:9092] -t [topic] [file.txt]

Consume with format

$ kafkacat -C -b [localhost:9092] -t [topic] -f '[%T] %k: %s\n'

Produce with key using delimiter

$ echo "[key]:[value]" | kafkacat -P -b [localhost:9092] -t [topic] -K ":"

Consume N messages and exit

$ kafkacat -C -b [localhost:9092] -t [topic] -c [10]

SYNOPSIS

kafkacat [options]

DESCRIPTION

kafkacat (also known as kcat) is a command-line Kafka producer and consumer. It's faster and simpler than Kafka's built-in shell scripts, useful for testing and debugging.

PARAMETERS

-P

Producer mode.

-C

Consumer mode.

-L

Metadata list mode.

-b brokers

Broker list.

-t topic

Topic name.

-p partition

Partition number.

-o offset

Offset: beginning, end, stored, or number.

-K delim

Key delimiter.

-f format

Output format string.

-c count

Exit after consuming count messages.

-e

Exit at end of topic.

-G group topic

Consumer group mode (high-level balanced consumer).

-X property=value

Set librdkafka property (e.g., security.protocol=SSL).

FORMAT STRINGS

$ %T  - Timestamp
%k  - Key
%s  - Message (payload)
%p  - Partition
%o  - Offset
%t  - Topic

INSTALL

brew install kafkacat

CAVEATS

Renamed to kcat in newer versions. Requires librdkafka. Not included with Kafka distribution. Some features need specific librdkafka version.

HISTORY

kafkacat was created by Magnus Edenhill, who also created librdkafka. It's been renamed to kcat but kafkacat remains widely used.