Troubleshooting the Camel Kafka Connector
This page describes some common pitfalls when deploying the connectors.
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
/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
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
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:
AMQP connector requires a JMS-compliant client (such as qpid-jms-client)
SJMS2 connector requires the client libraries for the protocol used to communicate with the broker (ie.: qpid-jms-client, activemq-client, artemis-jms-client, etc).
JDBC connector requires the JDBC client for the database
Do not use activemq-all 5.16.0 or older with the SJMS2 connector: the activemq-all jar contains packages older versions of Camel that cause conflict when trying to run the connector. You may find very interesting errors such as
java.lang.NoSuchMethodError: org.apache.camel.main.Main.configure()Lorg/apache/camel/main/MainConfigurationPropertieswhen trying to do so.