[KAFKA-17150] Connect converter validation does not accept class aliases

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 3.8.0
• Fix Version/s: 3.8.0
• Component/s: connect
• Assignee: Greg Harris
• Reporter: Greg Harris
• Created: 16/Jul/24 21:14
• Updated: 18/Jul/24 00:13
• Resolved: 18/Jul/24 00:13

Description

Connect allows users to specify aliases instead of full classes when configuring plugins. For example, the following configuration is valid:

{
        "connector.class": "FileStreamSource",
        "topic": "anything",
        "key.converter": "JsonConverter"
}

In <= 3.7.1 this will pass validation and function correctly.

In 3.8.0-rc1 this will instead fail with this error message:

[2024-07-16 13:58:54,250] ERROR Failed to instantiate key converter class JsonConverter; this should have been caught by prior validation logic (org.apache.kafka.connect.runtime.AbstractHerder:462)
java.lang.ClassNotFoundException: JsonConverter
	at java.base/java.lang.Class.forName0(Native Method)
	at java.base/java.lang.Class.forName(Class.java:534)
	at java.base/java.lang.Class.forName(Class.java:513)
	at org.apache.kafka.common.utils.Utils.loadClass(Utils.java:426)
	at org.apache.kafka.common.utils.Utils.newInstance(Utils.java:415)
	at org.apache.kafka.connect.runtime.AbstractHerder.validateConverterConfig(AbstractHerder.java:460)
	at org.apache.kafka.connect.runtime.AbstractHerder.validateKeyConverterConfig(AbstractHerder.java:528)
	at org.apache.kafka.connect.runtime.AbstractHerder.validateConnectorConfig(AbstractHerder.java:734)
	at org.apache.kafka.connect.runtime.AbstractHerder.lambda$validateConnectorConfig$3(AbstractHerder.java:574)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:572)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
	at java.base/java.lang.Thread.run(Thread.java:1583)

and this error will eventually be shown to the user:

Connector configuration is invalid and contains the following 1 error(s):
Failed to load class JsonConverter: JsonConverter

When the full class name is specified, the class is found and passes validation.

Issue Links

• is caused by: KAFKA-13329 Connect does not perform preflight validation for per-connector key and value converters
• is related to: KAFKA-8550 Connector validation fails with aliased converters
• links to: GitHub Pull Request #16608