如何将 SMT 应用于 Kafka 连接中的单个主题？

Question

我想将一组 SMT（单消息转换）应用到一个主题。

我有以下配置..

connector.class: io.debezium.connector.postgresql.PostgresConnector
name: test
database.server.name: testserver
database.hostname: 127.0.0.1
database.port: 5432
database.dbname: test
database.user: testuser
database.password: "testpass"
schema.whitelist: test

table.whitelist: test.topic1, test.topic2, test.topic3

transforms:unwrap,extractTopic1Key,extractTopic1Value,extractTopic2Key


transforms.unwrap.type: io.debezium.transforms.UnwrapFromEnvelope
transforms.unwrap.delete.handling.mode: rewrite
transforms.unwrap.drop.tombstones: false

transforms.extractTopic1Key.type: org.apache.kafka.connect.transforms.ExtractField$Key
transforms.extractTopic1Value.type: org.apache.kafka.connect.transforms.ExtractField$Value

transforms.extractTopic1Key.field: propname
transforms.extractTopic1Value.field: propvalue

transforms.extractTopic1Key.predicate: test_topic1
transforms.extractTopic1Value.predicate: test_topic1

transforms.extractTopic2Key.type:org.apache.kafka.connect.transforms.ExtractField$Key
transforms.extractTopic2Key.field: id
transforms.extractTopic2Key.predicate: test_topic2


predicates=test_topic1,test_topic2
predicates.test_topic1.type=org.apache.kafka.connect.predicates.TopicNameMatches
predicates.test_topic1.pattern=.*topic1

predicates.test_topic2.type=org.apache.kafka.connect.predicates.TopicNameMatches
predicates.test_topic2.pattern=.*topic2

key.converter: org.apache.kafka.connect.json.JsonConverter
key.converter.schemas.enable: false
value.converter: org.apache.kafka.connect.json.JsonConverter
value.converter.schemas.enable: false
decimal.handling.mode: string
include.schema.changes: false
#Adds header which says insert,update,delete
transforms.unwrap.operation.header: true
snapshot.mode: initial
heartbeat.interval.ms: 10000
slot.name: test

我收到以下错误..

org.apache.kafka.connect.errors.ConnectException: Tolerance exceeded in error handler
        at org.apache.kafka.connect.runtime.errors.RetryWithToleranceOperator.execAndHandleError(RetryWithToleranceOperator.java:178)
        at org.apache.kafka.connect.runtime.errors.RetryWithToleranceOperator.execute(RetryWithToleranceOperator.java:104)
        at org.apache.kafka.connect.runtime.TransformationChain.apply(TransformationChain.java:50)
        at org.apache.kafka.connect.runtime.WorkerSourceTask.sendRecords(WorkerSourceTask.java:308)
        at org.apache.kafka.connect.runtime.WorkerSourceTask.execute(WorkerSourceTask.java:234)
        at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:177)
        at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:227)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
        at org.apache.kafka.connect.transforms.ExtractField.apply(ExtractField.java:61)
        at org.apache.kafka.connect.runtime.TransformationChain.lambda$apply$0(TransformationChain.java:50)
        at org.apache.kafka.connect.runtime.errors.RetryWithToleranceOperator.execAndRetry(RetryWithToleranceOperator.java:128)
        at org.apache.kafka.connect.runtime.errors.RetryWithToleranceOperator.execAndHandleError(RetryWithToleranceOperator.java:162)
        ... 11 more

当我删除除unwrap 之外的所有转换时，它工作正常。 我的示例主题数据如下所示。

键

{"propname":"my.test.prop"} 

价值

{"propname":"my.test.prop","propvalue":"10","__deleted":"false"}

propname是表中的主键。

上述配置有什么问题，我们如何将特定的 SMT 仅应用于指定的主题？

P.S：我使用的是 Confluent Platform 5.3.1

Answer 1

apache-kafka 包括支持从 2.6.0 版本到KIP-585 - Filter and Conditional SMTs 有条件地应用 SMT。

您使用的是 Confluent Platform 5.3.1。 5.3.1 是 Confluent Platform 的一个错误修复版本，为您提供 Apache Kafka 2.3.0，这是 Kafka 的最新稳定版本。

所以你需要将 Kafka Connect 升级到 2.6.0 版本。