The out_kafka2 Output plugin writes records into Apache Kafka.


out_kafka2 is included in td-agent. Fluentd gem users will need to install the fluent-plugin-kafka gem using the following command:

$ fluent-gem install fluent-plugin-kafka

Example Configuration

<match pattern>
  @type kafka2

  # list of seed brokers
  brokers <broker1_host>:<broker1_port>,<broker2_host>:<broker2_port>
  use_event_time true

  # buffer settings
  <buffer topic>
    @type file
    path /var/log/td-agent/buffer/td
    flush_interval 3s

  # data type settings
    @type json

  # topic settings
  topic_key topic
  default_topic messages

  # producer settings
  required_acks -1
  compression_codec gzip

Please see the Configuration File article for the basic structure and syntax of the configuration file.

Please make sure that you have enough space in the buffer path directory. Running out of disk space is a problem frequently reported by users.


@type (required)

The value must be kafka2.

brokers (required/optional)

The list of all seed brokers, with their host and port information.

Default: localhost:9092


The field name for the target topic. If the field value is app, this plugin writes events to the app topic.

This field name must be included in the buffer chunk keys:

topic_key category
<buffer category> # topic_key should be included in buffer chunk key
  # ...

Default: topic


The name of the default topic. (default: nil)

This value will be used when the topic_key field is missing.

<format> Directive

The format of each message. The available options are json, ltsv, and formatter plugins.

Here is the json example:

  @type json

See formatter article for more detail.


Set fluentd event time to Kafka's CreateTime.

Default: false (It means the current time.)


The number of acks required per request.

Default: -1


The codec the producer uses to compress messages (default: nil).

Default: nil

Available options: gzip, snappy

For snappy, you need to install snappy gem by td-agent-gem command.


The @log_level option allows the user to set different levels of logging for each plugin.

Supported log levels: fatal, error, warn, info, debug, trace.

Please see the logging article for further details.

Common Output / Buffer parameters

For common output / buffer parameters, please check the following articles:

Further Reading

This page does not describe all the possible configurations. If you want to know about other configurations, please check the link below:

If this article is incorrect or outdated, or omits critical information, please let us know. Fluentd is an open-source project under Cloud Native Computing Foundation (CNCF). All components are available under the Apache 2 License.

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