[jira] [Created] (SPARK-31805) Spark Structured Streaming with "assign" KafkaConsumer mode still uses group.id

["Arseniy Tashoyan (Jira)" <ji...@apache.org>]

Arseniy Tashoyan created SPARK-31805:
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             Summary: Spark Structured Streaming with "assign" KafkaConsumer mode still uses group.id
                 Key: SPARK-31805
                 URL: https://issues.apache.org/jira/browse/SPARK-31805
             Project: Spark
          Issue Type: Bug
          Components: Structured Streaming
    Affects Versions: 2.4.5, 3.0.0
            Reporter: Arseniy Tashoyan


[Spark Structured Streaming - Kafka integration|https://spark.apache.org/docs/latest/structured-streaming-kafka-integration.html#creating-a-kafka-source-for-batch-queries] provides the [assign|https://kafka.apache.org/25/javadoc/org/apache/kafka/clients/consumer/KafkaConsumer.html#assign-java.util.Collection-] strategy to consume data from Kafka. This strategy assumes manual assignment of offsets in topic partitions. The consumer group in the assign strategy is not used.

When creating a consumer to read data, Spark provides an internally-generated group id like this:

[KafkaRelation|https://github.com/apache/spark/blob/bcadd5c3096109878fe26fb0d57a9b7d6fdaa257/external/kafka-0-10-sql/src/main/scala/org/apache/spark/sql/kafka010/KafkaRelation.scala#L60]:
{code:scala}
val uniqueGroupId = s"spark-kafka-relation-${UUID.randomUUID}"
{code}

This is done for any consumer strategy, even for "assign". The problem is that with a secured Kafka cluster a client cannot use an arbitrary consumer group id. That's why a Structured Streaming application fails with an exception like:

{code:none}
org.apache.kafka.common.errors.GroupAuthorizationException: Not authorized to access group: spark-kafka-relation-ecab045d-4ee6-425e-88a0-495d4100a013-driver-0
{code}
 
In Spark 3.0.0, this problem could be avoided by two workarounds:
- SPARK-26121: Specify a custom prefix for the consumer group id generated by Spark (allowed by the broker)
- SPARK-26350: Specify a custom group id

However, with the "assign" strategy the user does not need to worry about consumer group - the consumer group should be disregarded. Therefore a better fix could be to not set the consumer property "group.id" when using the "assign" strategy.





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