Using a compacted Kafka topic to keep a local cache in every pod

Disclosure: I used AI assistance to edit this text and code. The implementation and production experience behind it are mine. This post came from this recent discussion: https://www.reddit.com/r/apachekafka/comments/1vhv9nn/can_kafka_replace_redis_for_cache_synchronization/ ; as initial post was about k8s / sping-boot stack here I also operate with them. The question was whether Kafka can replace Redis for synchronizing a cache across about 25 Spring Boot pods. I have used this pattern in production, and the answer is yes for some types of data, but there are a few details that are easy to mis