setting offsets.retention.minutes in spec.kafka.config doesn't seem to have any effect

[rubensayshi]

Describe the bug
setting offsets.retention.minutes in spec.kafka.config doesn't seem to have any effect on the __consumer_offsets topic.

To Reproduce

1. Create a kafka resource with offsets.retention.minutes set in spec.kafka.config
2. Check the kube describe kafkatopic consumer-offsets
3. See there spec is set to compact without any retention params.

Expected behavior
I would expect the retention to be applied to the __consumer-offsets topic, to avoid my offsets being lost when a consumer hasn't been alive for a while longer than the default 7 days (which also happens if there just weren't any new messages on the topic).

YAML files and logs

apiVersion: kafka.strimzi.io/v1beta2
kind: Kafka
metadata:
  name: main
  namespace: kafka
spec:
  kafka:
    version: 3.0.0
    replicas: 2
    authorization:
      type: simple
    listeners:
      - name: tls
        port: 9093
        type: internal
    config:
      offsets.retention.minutes: 525600

Additional notes
I do see the value set in the config file on the pod (custom-config/server.config)

[scholzj]

Strimzi just passes the value to Kafka. So if you see it in the configuration file, there is not much more Strimzi can do about it.

[rubensayshi]

hmm, I can see there's a kafkatopic k8s resource for the __consumer-offsets topic, is that strimzi reflecting a topic that was made automatically by kafka itself or is strimzi creating that topic?

I'm having a hard time figuring this our from the strimzi code, but if strimzi is creating this topic ahead of kafka creating it then maybe that could be the problem?

[scholzj]

A lot depends on your configuration and how you use Strimzi. In general, Kafka creates the consumer offsets topic. The KAfTopic is just a reflection of it created by the Topic Operator.