Publishing an AVRO messages to Kafka via Kafka REST - apache-kafka

Question

We have deployed Confluent Platform 6.0 in our Kubernetes cluster. I have created a Kafka topic "test-topic-1" via Kafka REST api. Now I'm trying to publish a simple AVRO message to this topic.
curl --location --request POST 'https://kafka-rest-master.k8s.hip.com.au/topics/test-topic-1' \
--header 'Content-Type: application/vnd.kafka.avro.v2+json' \
--header 'Accept: application/vnd.kafka.v2+json' \
--data-raw '{"value_schema":{"type":"record","name":"User","fields":[{"name":"name","type":"string"}]},"records":[{"value":{"name":"testUser"}}]}'
I get a 500 error response for this request,
{"error_code":500,"message":"Internal Server Error"}
When I check the logs of the kafka rest pod, I can see the following error,
ERROR Request Failed with exception
(io.confluent.rest.exceptions.DebuggableExceptionMapper)
com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot
deserialize instance of java.lang.String out of START_OBJECT token
at [Source:
(org.glassfish.jersey.message.internal.ReaderInterceptorExecutor$UnCloseableInputStream);
line: 1, column: 17] (through ref erence chain:
io.confluent.kafkarest.entities.v2.SchemaTopicProduceRequest["value_schema"])
at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:59)
at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1445)
Am I following the correct steps to publish an AVRO message to a newly created Kafka topic? If so what could be the problem here?

Answer 1

your AVRO schema definition is wrong. It should be defined as the following
{
"type": "record",
"name": "recordName",
"namespace": "namespace",
"doc": "description",
"fields": [
{
"name": "key",
"type": {
"type": "string",
"avro.java.string": "String"
}
}
]
}
OR
"fields": [
{
"name": "fiedName",
"type": "string"
},
]