We kicked off this series by seeing on day 1 how to use InsertField
to add in the timestamp to a message passing through the Kafka Connect sink connector. Today weβll see how to use the same Single Message Transform to add in a static field value, as well as the name of the Kafka topic, partition, and offset from which the message has been read.
"transforms" : "insertStaticField1",
"transforms.insertStaticField1.type" : "org.apache.kafka.connect.transforms.InsertField$Value",
"transforms.insertStaticField1.static.field": "sourceSystem",
"transforms.insertStaticField1.static.value": "NeverGonna"
Adding fields to messages at ingest in the Kafka Connect source connector
When ingesting data from a source it can be useful to add fields to store information such as the server from which it was read.
Hereβs an example source connector, which adds
curl -i -X PUT -H "Content-Type:application/json" \
http://localhost:8083/connectors/source-voluble-datagen-day6-00/config \
-d '{
"connector.class" : "io.mdrogalis.voluble.VolubleSourceConnector",
"genkp.day6-transactions.with" : "#{Internet.uuid}",
"genv.day6-transactions.cost.with" : "#{Commerce.price}",
"genv.day6-transactions.card_type.with" : "#{Business.creditCardType}",
"genv.day6-transactions.item.with" : "#{Beer.name}",
"topic.day6-transactions.throttle.ms" : 5000,
"transforms" : "insertStaticField1,insertStaticField2",
"transforms.insertStaticField1.type" : "org.apache.kafka.connect.transforms.InsertField$Value",
"transforms.insertStaticField1.static.field": "sourceSystem",
"transforms.insertStaticField1.static.value": "NeverGonna",
"transforms.insertStaticField2.type" : "org.apache.kafka.connect.transforms.InsertField$Value",
"transforms.insertStaticField2.static.field": "ingestAgent",
"transforms.insertStaticField2.static.value": "GiveYouUp"
}'
The resulting message thatβs written to Kafka includes the data from the source system (a data generator, in this case, writing fields cost
, card_type
, and item
), plus the static fields configured (sourceSystem
, ingestAgent
):
docker exec kafkacat kafkacat -b broker:29092 -r http://schema-registry:8081 -s key=s -s value=avro -t day6-transactions -C -c1 -o end -u -q -J | jq '.payload'
{
"cost": {
"string": "25.79"
},
"card_type": {
"string": "visa"
},
"item": {
"string": "Westmalle Trappist Tripel"
},
"sourceSystem": {
"string": "NeverGonna"
},
"ingestAgent": {
"string": "GiveYouUp"
}
}
Adding details about the Kafka message at egress with a Kafka Connect sink connector
π https://www.confluent.io/hub/confluentinc/kafka-connect-jdbc
See also π₯ Kafka Connect in Action : JDBC Sink (πΎ demo code
) and π₯ ksqlDB & Kafka Connect JDBC Sink in action (πΎ demo code
)
It can often be useful to add information about the Kafka message (topic, partition, offset) when the data is sent to a target system. Hereβs an example using the above topic, with another static field added in for good measure. You can also add the timestamp of the Kafka message, as shown previously.
curl -i -X PUT -H "Accept:application/json" \
-H "Content-Type:application/json" http://localhost:8083/connectors/sink-jdbc-mysql-day6-00/config \
-d '{
"connector.class" : "io.confluent.connect.jdbc.JdbcSinkConnector",
"connection.url" : "jdbc:mysql://mysql:3306/demo",
"connection.user" : "mysqluser",
"connection.password" : "mysqlpw",
"topics" : "day6-transactions",
"tasks.max" : "4",
"auto.create" : "true",
"auto.evolve" : "true",
"transforms" : "insertPartition,insertOffset,insertTopic",
"transforms.insertPartition.type" : "org.apache.kafka.connect.transforms.InsertField$Value",
"transforms.insertPartition.partition.field": "kafkaPartition",
"transforms.insertOffset.type" : "org.apache.kafka.connect.transforms.InsertField$Value",
"transforms.insertOffset.offset.field" : "kafkaOffset",
"transforms.insertTopic.type" : "org.apache.kafka.connect.transforms.InsertField$Value",
"transforms.insertTopic.topic.field" : "kafkaTopic"
}'
Hereβs the data as it appears in the target system:
mysql> SELECT * FROM `day6-transactions` LIMIT 5;
+-------+-----------+---------------------+--------------+-------------+----------------+-------------+-------------------+
| cost | card_type | item | sourceSystem | ingestAgent | kafkaPartition | kafkaOffset | kafkaTopic |
+-------+-----------+---------------------+--------------+-------------+----------------+-------------+-------------------+
| 11.78 | visa | Schneider Aventinus | NeverGonna | GiveYouUp | 0 | 0 | day6-transactions |
| 17.65 | discover | Two Hearted Ale | NeverGonna | GiveYouUp | 0 | 1 | day6-transactions |
| 11.63 | jcb | Stone IPA | NeverGonna | GiveYouUp | 0 | 2 | day6-transactions |
| 67.51 | switch | Shakespeare Oatmeal | NeverGonna | GiveYouUp | 0 | 3 | day6-transactions |
| 22.25 | discover | Hop Rod Rye | NeverGonna | GiveYouUp | 0 | 4 | day6-transactions |
+-------+-----------+---------------------+--------------+-------------+----------------+-------------+-------------------+
5 rows in set (0.00 sec)
Top comments (0)