Question

我正在尝试使用新功能（https://www.confluent.io/blog/put-several-event-types-kafka-topic/）来存储两个关于同一主题的不同类型的事件。实际上我使用Confluent版本4.1.0并在下面设置这些属性实现这一目标

properties.put(KafkaAvroSerializerConfig.VALUE_SUBJECT_NAME_STRATEGY,TopicRecordNameStrategy.class.getName());
properties.put("value.multi.type", true);

数据被写入主题没有问题，可以从Kafka Streams应用程序看作Generic Avro Records。也在Kafka Schema注册表中，为该特定主题上托管的每个事件创建了两个新条目。

我面临的问题是我无法使用Kafka Connect从此主题导出这些数据。在最简单的情况下我使用文件接收器连接器如下

{
  "name": "sink-connector",
  "config": {
      "topics": "source-topic",
      "connector.class": "org.apache.kafka.connect.file.FileStreamSinkConnector",
      "tasks.max": 1,
      "key.converter": "org.apache.kafka.connect.storage.StringConverter",
      "key.converter.schema.registry.url":"http://kafka-schema-registry:8081",
      "value.converter":"io.confluent.connect.avro.AvroConverter",
      "value.converter.schema.registry.url":"http://kafka-schema-registry:8081",
      "value.subject.name.strategy":"io.confluent.kafka.serializers.subject.TopicRecordNameStrategy",
      "file": "/tmp/sink-file.txt"
    }
}

我从连接器收到错误，似乎是某种基于AvroConverter的序列化错误这里显示的那个

org.apache.kafka.connect.errors.DataException: source-topic
    at io.confluent.connect.avro.AvroConverter.toConnectData(AvroConverter.java:95)
    at org.apache.kafka.connect.runtime.WorkerSinkTask.convertMessages(WorkerSinkTask.java:468)
    at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:301)
    at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:205)
    at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:173)
    at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:170)
    at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:214)
    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)
Caused by: org.apache.kafka.common.errors.SerializationException: Error retrieving Avro schema for id 2
Caused by: io.confluent.kafka.schemaregistry.client.rest.exceptions.RestClientException: Subject not found.; error code: 40401
    at io.confluent.kafka.schemaregistry.client.rest.RestService.sendHttpRequest(RestService.java:202)
    at io.confluent.kafka.schemaregistry.client.rest.RestService.httpRequest(RestService.java:229)
    at io.confluent.kafka.schemaregistry.client.rest.RestService.lookUpSubjectVersion(RestService.java:296)
    at io.confluent.kafka.schemaregistry.client.rest.RestService.lookUpSubjectVersion(RestService.java:284)
    at io.confluent.kafka.schemaregistry.client.CachedSchemaRegistryClient.getVersionFromRegistry(CachedSchemaRegistryClient.java:125)
    at io.confluent.kafka.schemaregistry.client.CachedSchemaRegistryClient.getVersion(CachedSchemaRegistryClient.java:236)
    at io.confluent.kafka.serializers.AbstractKafkaAvroDeserializer.deserialize(AbstractKafkaAvroDeserializer.java:152)
    at io.confluent.kafka.serializers.AbstractKafkaAvroDeserializer.deserializeWithSchemaAndVersion(AbstractKafkaAvroDeserializer.java:194)
    at io.confluent.connect.avro.AvroConverter$Deserializer.deserialize(AvroConverter.java:120)
    at io.confluent.connect.avro.AvroConverter.toConnectData(AvroConverter.java:83)
    at org.apache.kafka.connect.runtime.WorkerSinkTask.convertMessages(WorkerSinkTask.java:468)
    at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:301)
    at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:205)
    at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:173)
    at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:170)
    at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:214)
    at java.util.concurrent.Executors$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)

请注意，架构注册表具有ID为2的Avro架构，而另一个架构ID为3，用于描述托管在其上的两个事件同一主题。使用JDBC连接器时会出现同样的问题。

那么我如何处理这种情况才能从我的Kafka集群中导出数据到外部系统。我在配置上遗漏了什么吗？是否可以拥有包含多种类型事件的主题并通过Kafka Connect导出它们？

Answer 1

找到解决方案。我的代码将密钥作为String传递，值为avro。阅读时的Hive-sink试图查找密钥的avro架构并且无法找到它。添加属性 key.converter = org.apache.kafka.connect.storage.StringConverter key.converter.schema.registry.url = http://localhost:8081 帮助解决了这个问题。

Kafka Connect从同一主题导出多个事件类型

1 个答案: