Configuring event streams

The event streaming plugin for Apache Kafka is configured using command line options.

Ensure a Kafka system is available to receive streams from Hyperledger Besu.

Info

Hyperledger Besu is compatible with Kafka versions 2.5.0 and above.

Multiple topics are created for each event stream in the format <stream_prefix><domain_type>, where the domain types are:

block
transaction
smart-contract
node
log

<stream_prefix> is defined using --plugin-kafka-stream.

Configuring a Kafka event stream

Configure a Kafka event stream in the command line by enabling the plugin and setting the appropriate options.

Example

besu --plugin-kafka-enabled --plugin-kafka-stream=my-besu-stream --plugin-kafka-url=127.0.0.1:9090 --plugin-kafka-producer-config-override-enabled --plugin-kafka-producer-property=sasl.mechanism=PLAIN

The command line specifies:

Enable the Kafka plugin using the --plugin-kafka-enabled option.
Prefix to identify the stream in Kafka using the --plugin-kafka-stream option.
URL endpoint of the Kafka stream using the --plugin-kafka-url option.
Restrict broadcasted event topics with the --plugin-kafka-enabled-topic option.
Override Kafka Producer configuration properties using the --plugin-kafka-producer-config-override-enabled option.
Kafka Producer configuration property using the --plugin-kafka-producer-property option. If multiple properties are required, the --plugin-kafka-producer-property option can be specified multiple times.

Note

If --plugin-kafka-url is not specified, the plugin attempts to connect to a local Kafka broker at 127.0.0.1:9092.

Filtering smart contract event logs

You can configure event streaming plugins to filter event logs from specified smart contracts. To create the filter, use the following CLI options:

To display the filtered events in a more readable format, create a schema file to decode the events. To specify the schema file location, use the --plugin-kafka-log-schema-file option.