[Enhancement]: Ability to check a condition when updating a kafkanodepool for rollout completion

[jack1902]

Related problem

When creating/updating a kafkanodepool, it would be great to have something on the nodepool itself i could monitor to detect convergence on the spec.

For example, given a kafkanodepool with roles controller and an update to controller,broker, i currently see no way to easily detect the completion of the broker role addition to all the replicas within a given nodepool.

Suggested solution

Extension of the kafkaNodePool resource to include some conditions such as, but not limited to:

• Ready
• Phase (updating, complete)

Alternatives

I have currently hacked around this by utilising the .status.labelSelector of the nodepool, to filter for all pods the nodepool targets and consistently checking two things:

• are the pods "Ready"
• is the value of the label strimzi.io/broker-role="true"

Additional context

I've migrated from the flat kafka resource to a single kafkaNodePool. Along the way i had to:

• migrate from zookeeper -> kraft (the .status.kafkaMetadataState on the kafka resource is <3)
• reduce 3x controller 3xbroker down to 3x controller,broker

[scholzj]

I'm not sure whether a phase or readiness of the KafkaNodePool resource is the right thing because they would be hard to maintain and find a proper meaning for them. Observed generation would make more sense -> likely in the Kafka CR or in the KafkaNodePool CR. But implementation wise it would be easier in the Kafka CR I guess. Comparing the observed generation of the node pool in the Kafka CR status with the KafkaNodePool generation would then show if everything is up to date.

[ppatierno]

Triaged on 23.1.2025: keep this for the next community calls. Maintainers will think more about it looking at options about how to do support this, which looks to make sense anyway.

[katheris]

Triaged on 20.2.2025: We think this enhancement is worth doing but it would need a proposal first to work out the best approach