Ewen Cheslack-Postava created KAFKA-5164:
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Summary: SetSchemaMetadata does not replace the schemas in structs
correctly
Key: KAFKA-5164
URL: https://issues.apache.org/jira/browse/KAFKA-5164
Project: Kafka
Issue Type: Bug
Components: KafkaConnect
Affects Versions: 0.10.2.1
Reporter: Ewen Cheslack-Postava
In SetSchemaMetadataTest we verify that the name and version of the schema in
the record have been replaced:
https://github.com/apache/kafka/blob/trunk/connect/transforms/src/test/java/org/apache/kafka/connect/transforms/SetSchemaMetadataTest.java#L62
However, in the case of Structs, the schema will be attached to both the record
and the Struct itself. So we correctly rebuild the Record:
https://github.com/apache/kafka/blob/trunk/connect/transforms/src/main/java/org/apache/kafka/connect/transforms/SetSchemaMetadata.java#L77
https://github.com/apache/kafka/blob/trunk/connect/transforms/src/main/java/org/apache/kafka/connect/transforms/SetSchemaMetadata.java#L104
https://github.com/apache/kafka/blob/trunk/connect/transforms/src/main/java/org/apache/kafka/connect/transforms/SetSchemaMetadata.java#L119
But if the key or value are a struct, they will still contain the old schema
embedded in the struct.
Ultimately this can lead to validations in other code failing (even for very
simple changes like adjusting the name of a schema):
{code}
(org.apache.kafka.connect.runtime.WorkerTask:141)
org.apache.kafka.connect.errors.DataException: Mismatching struct schema
at io.confluent.connect.avro.AvroData.fromConnectData(AvroData.java:471)
at io.confluent.connect.avro.AvroData.fromConnectData(AvroData.java:295)
at
io.confluent.connect.avro.AvroConverter.fromConnectData(AvroConverter.java:73)
at
org.apache.kafka.connect.runtime.WorkerSourceTask.sendRecords(WorkerSourceTask.java:196)
at
org.apache.kafka.connect.runtime.WorkerSourceTask.execute(WorkerSourceTask.java:167)
at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:139)
at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:182)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
{code}
The solution to this is probably to check whether we're dealing with a Struct
when we use a new schema and potentially copy/reallocate it.
This particular issue would only appear if we don't modify the data, so I think
SetSchemaMetadata is currently the only transformation that would have the
issue.
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