I can stream data from Kafka to MongoDB.
I stream by kafka-console-producer.sh
with a json message(for example: {"id": 1, "test": 123}
). It is inserted into MongoDB successfully.
However, if I stream a message (for example: abc
). Then, I will get the error because of json parsing
[2019-07-09 14:44:30,365] ERROR WorkerSinkTask{id=mongo-sink-0} Task threw an uncaught and unrecoverable exception (org.apache.kafka.connect.runtime.WorkerTask)
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.WorkerSinkTask.convertAndTransformRecord(WorkerSinkTask.java:487)
at org.apache.kafka.connect.runtime.WorkerSinkTask.convertMessages(WorkerSinkTask.java:464)
at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:320)
at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:224)
at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:192)
at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:175)
at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:219)
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: org.apache.kafka.connect.errors.DataException: Converting byte[] to Kafka Connect data failed due to serialization error:
at org.apache.kafka.connect.json.JsonConverter.toConnectData(JsonConverter.java:344)
at org.apache.kafka.connect.runtime.WorkerSinkTask.lambda$convertAndTransformRecord$1(WorkerSinkTask.java:487)
at org.apache.kafka.connect.runtime.errors.RetryWithToleranceOperator.execAndRetry(RetryWithToleranceOperator.java:128)
at org.apache.kafka.connect.runtime.errors.RetryWithToleranceOperator.execAndHandleError(RetryWithToleranceOperator.java:162)
... 13 more
Caused by: org.apache.kafka.common.errors.SerializationException: com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'abc': was expecting ('true', 'false
' or 'null')
at [Source: (byte[])"abc"; line: 1, column: 7]
Caused by: com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'abc': was expecting ('true', 'false' or 'null')
at [Source: (byte[])"abc"; line: 1, column: 7]
at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1804)
at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:703)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._reportInvalidToken(UTF8StreamJsonParser.java:3532)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._handleUnexpectedValue(UTF8StreamJsonParser.java:2627)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._nextTokenNotInObject(UTF8StreamJsonParser.java:832)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser.nextToken(UTF8StreamJsonParser.java:729)
at com.fasterxml.jackson.databind.ObjectMapper._readTreeAndClose(ObjectMapper.java:4042)
at com.fasterxml.jackson.databind.ObjectMapper.readTree(ObjectMapper.java:2571)
at org.apache.kafka.connect.json.JsonDeserializer.deserialize(JsonDeserializer.java:50)
at org.apache.kafka.connect.json.JsonConverter.toConnectData(JsonConverter.java:342)
at org.apache.kafka.connect.runtime.WorkerSinkTask.lambda$convertAndTransformRecord$1(WorkerSinkTask.java:487)
at org.apache.kafka.connect.runtime.errors.RetryWithToleranceOperator.execAndRetry(RetryWithToleranceOperator.java:128)
at org.apache.kafka.connect.runtime.errors.RetryWithToleranceOperator.execAndHandleError(RetryWithToleranceOperator.java:162)
at org.apache.kafka.connect.runtime.errors.RetryWithToleranceOperator.execute(RetryWithToleranceOperator.java:104)
at org.apache.kafka.connect.runtime.WorkerSinkTask.convertAndTransformRecord(WorkerSinkTask.java:487)
at org.apache.kafka.connect.runtime.WorkerSinkTask.convertMessages(WorkerSinkTask.java:464)
at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:320)
at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:224)
at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:192)
at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:175)
at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:219)
at java.util.concurrent.Executors$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$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
[2019-07-09 14:44:30,374] ERROR WorkerSinkTask{id=mongo-sink-0} Task is being killed and will not recover until manually restarted (org.apache.kafka.connect.runtime.Wor
kerTask)
The sink connector configuration file is MongoSinkConnector.properties
with content (I create it based on this source )
name=mongo-sink
topics=test
connector.class=com.mongodb.kafka.connect.MongoSinkConnector
tasks.max=1
key.ignore=true
# Specific global MongoDB Sink Connector configuration
connection.uri=mongodb://localhost:27017
database=test_kafka
collection=transaction
max.num.retries=3
retries.defer.timeout=5000
type.name=kafka-connect
key.converter=org.apache.kafka.connect.json.JsonConverter
key.converter.schemas.enable=false
value.converter=org.apache.kafka.connect.json.JsonConverter
value.converter.schemas.enable=false
I have 2 separated questions:
how to ignore the message which is non-json format?
how to defined a default-key for this kind of message (for example: abc
-> { "non-json": "abc" }
A String is "JSON format", however, The JsonConverter
typically expects JSON objects , or in some cases null
, not plain strings.
There is no property to set defaults for errors, but you can either simply skip the events, or send them to a different topic, which you must process & fix the messages separately if you expect them to also end up in the database. This is configured with the errors.tolerance
setting (only available since Kafka Connect 2.0)
Refer - https://www.confluent.io/blog/kafka-connect-deep-dive-error-handling-dead-letter-queues
If the data is just "abc"
, then I would suggest using StringConverter
rather than JsonConverter
anyways
But if you wanted to wrap all events in a JSON object (not just plain strings), you would have to add transforms
property
transforms=MakeMap
transforms.MakeMap.type=org.apache.kafka.connect.transforms.HoistField$Value
transforms.MakeMap.field=non-json
This would take "abc"
to {"non-json":"abc"}
as well as {"id": 1, "test": 123}
to {"non-json":{"id": 1, "test": 123}}
, so you need to be careful about what you are producing into the topic.
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