When Kafka Offset committing is enabled and done on Flinks checkpointing, an error might occur if one Kafka broker is shutdown which might be the leader of that partition in Kafkas internal __consumer_offsets topic.
This is an expected behaviour. But once the broker is started up again, the next checkpoint issued by flink should commit the meanwhile processed offsets back to kafka. Somehow this does not seem to happen always in Flink 1.15.0 anymore and the offset committing is broken. An warning like the following will be logged on each checkpoint:
To reproduce this I've attached a small flink job program. To execute this java8, scala sbt and docker / docker-compose is required. Also see readme.md for more details.
The job can be run with `sbt run`, kafka cluster is started by `docker-compose up`. If then the kafka brokers are restarted gracefully by e.g. `docker-compose stop kafka1` and `docker-compose start kafka1` with kafka2 and kafka3 afterwards, this warning will occur and no offsets will be committed into kafka.
This is not reproducible in flink 1.14.4.