Troubleshooting the Camel Kafka Connector

If the Kafka Connect runtime is not loading the Camel connector, the cause could be an incorrect directory structure. There is a specific directory structure that needs to be followed when installing the connectors. They are meant to be installed in a subdirectory of the Kafka Connect plugin.path and every connector should be within its own directory.

For example, if you have set the value of plugin.path to /camel-kafka-connectors/ then every connector should be within a directory inside it:

It’s possible to have multiple connectors in the plugin.path, therefore in a setup with both amqp and hdfs connectors, it would be possible to have a directory structure like this:

A common root cause for Kafka Connect failing to serialize or deserialize the data in transit is incorrect values for the key.converter or the value.converter (or both). There are usually verifiable in the logs by looking for Caused by: org.apache.kafka.common.errors.SerializationException or Caused by: org.apache.kafka.connect.errors.DataException.

Here’s one example with trying to exchange data using the AMQP connector without setting the key.converter and value.converter correctly:

Caused by: org.apache.kafka.connect.errors.DataException: JsonConverter with schemas.enable requires "schema" and "payload" fields and may not contain additional fields. If you are trying to deserialize plain JSON data, set schemas.enable=false in your converter configuration.

When deploying the connector manually (ie.: without the assistance of tools such as Strimzi) you may need to make sure to provide the required runtime dependencies and their dependencies. Some notable examples are: