Migrating to KIP-848 and the new assignors, Live: A Visual Guide

KIP-848 is GA, but the migration is still ahead of most teams. At its core is the protocol switch: the Classic rebalance protocol is on a deprecation path (KIP-1274). But there's a second story that lands directly on applications: assignors. KIP-848 moves assignment from a client-side, leader-driven election to broker-hosted pluggable assignors, so teams with specific assignment needs face a real question: what do I do about my custom, client-side assignor, and how do I move it to the new world in the 4.x releases?

This session covers the assignor migration in as much depth as the protocol switch itself. We'll demystify how assignment works in the KIP-848 era — the coordinator's target-assignment model and incremental reconciliation — then walk the move off classic client-side strategies to the broker side: how the built-in assignors map onto the two server-side ones, how to implement a custom assignor through the new server assignor SPI and enable it via group-level and client configuration, and how to observe, debug, and roll back the result with the new logs and metrics. We'll ground it all in a live visual simulator of the group coordinator and its members — watching a real Classic group migrate on stage, with heartbeats, epochs, reconciliation, and offset commits visible as they happen — alongside the protocol essentials: config changes, rolling upgrade and rollback, and the post-GA follow-ups.

Takeaways: A clear, visual model of the new protocol, and a concrete playbook for the assignor migration that comes with it — mapping the built-ins, implementing and enabling a custom server-side assignor, and verifying the result before 5.0, without sacrificing the resilience and operability benefits of KIP-848.

Who is it for:

Consumer-group owners planning their KIP-848 migration.
Platform and application engineers running Kafka at scale.
Teams with custom assignors that need to move to the broker-side assignors.