Kafka Streams ERROR Could not parse Avro schema

[berbarroso]

Hi,

I encountered an error when I tried this tutorial "How to filter a stream of events" using Kafka Streams.
Link: https://developer.confluent.io/tutorials/filter-a-stream-of-events/kstreams.html

On "Produce events to the input topic" section, I tried to run this command:
docker exec -i schema-registry /usr/bin/kafka-avro-console-producer --topic publications --bootstrap-server broker:9092 --property value.schema="$(< src/main/avro/publication.avsc)"

This is the error:
_[2024-03-20 07:14:22,648] ERROR Could not parse Avro schema (io.confluent.kafka.schemaregistry.avro.AvroSchemaProvider)
org.apache.avro.SchemaParseException: com.fasterxml.jackson.core.JsonParseException: Unrecognized token '$': was expecting (JSON String, Number, Array, Object or token 'null', 'true' or 'false')
at [Source: (String)"$(cat src/main/avro/publication.avsc)"; line: 1, column: 2]
at org.apache.avro.Schema$Parser.parse(Schema.java:1435)
at org.apache.avro.Schema$Parser.parse(Schema.java:1421)
at io.confluent.kafka.schemaregistry.avro.AvroSchema.(AvroSchema.java:76)
at io.confluent.kafka.schemaregistry.avro.AvroSchemaProvider.parseSchemaOrElseThrow(AvroSchemaProvider.java:53)
at io.confluent.kafka.schemaregistry.SchemaProvider.parseSchema(SchemaProvider.java:77)
at io.confluent.kafka.schemaregistry.SchemaProvider.parseSchema(SchemaProvider.java:86)
at io.confluent.kafka.formatter.SchemaMessageReader.parseSchema(SchemaMessageReader.java:221)
at io.confluent.kafka.formatter.SchemaMessageReader.getSchema(SchemaMessageReader.java:233)
at io.confluent.kafka.formatter.SchemaMessageReader.init(SchemaMessageReader.java:162)
at kafka.tools.ConsoleProducer$.main(ConsoleProducer.scala:42)
at kafka.tools.ConsoleProducer.main(ConsoleProducer.scala)
Caused by: com.fasterxml.jackson.core.JsonParseException: Unrecognized token '$': was expecting (JSON String, Number, Array, Object or token 'null', 'true' or 'false')
at [Source: (String)"$(cat src/main/avro/publication.avsc)"; line: 1, column: 2]
at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:2391)
at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:745)
at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._reportInvalidToken(ReaderBasedJsonParser.java:2961)
at com.fasterxml.jackson.core.json.ReaderBasedJsonParser.handleOddValue(ReaderBasedJsonParser.java:2002)
at com.fasterxml.jackson.core.json.ReaderBasedJsonParser.nextToken(ReaderBasedJsonParser.java:802)
at com.fasterxml.jackson.databind.ObjectMapper.readTree(ObjectMapper.java:2935)
at org.apache.avro.Schema$Parser.parse(Schema.java:1433)
... 10 more
java.util.NoSuchElementException: No value present
at java.base/java.util.Optional.get(Optional.java:148)
at io.confluent.kafka.formatter.SchemaMessageReader.parseSchema(SchemaMessageReader.java:221)
at io.confluent.kafka.formatter.SchemaMessageReader.getSchema(SchemaMessageReader.java:233)
at io.confluent.kafka.formatter.SchemaMessageReader.init(SchemaMessageReader.java:162)
at kafka.tools.ConsoleProducer$.main(ConsoleProducer.scala:42)
at kafka.tools.ConsoleProducer.main(ConsoleProducer.scala)

How to solve this problem?

Thank you in advance for answering! :)