Kafka

The Kafka input plugin allows subscribing to one or more Kafka topics to collect messages from an Apache Kafka service. This plugin uses the official librdkafka C library (built-in dependency).

Configuration Parameters

Key	Description	default
brokers	Single or multiple list of Kafka Brokers, e.g: 192.168.1.3:9092, 192.168.1.4:9092.
topics	Single entry or list of topics separated by comma (,) that Fluent Bit will subscribe to.
client_id	Client id passed to librdkafka.
group_id	Group id passed to librdkafka.	fluent-bit
poll_ms	Kafka brokers polling interval in milliseconds.	500
rdkafka.{property}	{property} can be any librdkafka properties

Getting Started

In order to subscribe/collect messages from Apache Kafka, you can run the plugin from the command line or through the configuration file:

Command Line

The kafka plugin can read parameters through the -p argument (property), e.g:

$ fluent-bit -i kafka -o stdout -p brokers=192.168.1.3:9092 -p topics=some-topic

Configuration File

In your main configuration file append the following Input & Output sections:

[INPUT]
    Name        kafka
    Brokers     192.168.1.3:9092
    Topics      some-topic
    poll_ms     100

[OUTPUT]
    Name        stdout

Example of using kafka input/output plugins

The fluent-bit source repository contains a full example of using fluent-bit to process kafka records:

[INPUT]
    Name kafka
    brokers kafka-broker:9092
    topics fb-source
    poll_ms 100

[FILTER]
    Name    lua
    Match   *
    script  kafka.lua
    call    modify_kafka_message

[OUTPUT]
    Name kafka
    brokers kafka-broker:9092
    topics fb-sink

The above will connect to the broker listening on kafka-broker:9092 and subscribe to the fb-source topic, polling for new messages every 100 milliseconds.

Every message received is then processed with kafka.lua and sent back to the fb-sink topic of the same broker.

The example can be executed locally with make start in the examples/kafka_filter directory (docker/compose is used).