The kafka write mode buffers data in Kafka before writing it to ClickHouse. This mode is useful when you have a high volume of data and want to avoid overwhelming ClickHouse. This mode takes advantage of ClickHouse’s kafka table engine.

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Setup

To set up Dittofeed with the kafka write mode, you can make use of the following environment variables: 
# necessary to use the write mode
WRITE_MODE=kafka
# the kafka host and portnames to write to
KAFKA_BROKERS=host1:port1,host2:port2
# the username and password to use for the kafka connection
KAFKA_USERNAME=my-kafka-username
KAFKA_PASSWORD=my-kafka-password
# whether to use SSL for the kafka connection
KAFKA_SSL=true
# the kafka sasl mechanism to use
# possible values are: plain, scram-sha-256, scram-sha-512
KAFKA_SASL_MECHANISM=plain
# the number of partitions to use for the user events topic when bootstrapping
KAFKA_USER_EVENTS_PARTITIONS=1
# the replication factor to use for the user events topic when bootstrapping
KAFKA_USER_EVENTS_REPLICATION_FACTOR=1
# the name of the user events topic to create when bootstrapping
USER_EVENTS_TOPIC_NAME=dittofeed-user-events
Finally, you can run the bootstrap script to create the necessary Kafka topic: 
BOOTSTRAP_KAFKA=true ./admin.sh bootstrap