[KAFKA-9100] The controller code allows for replicas to get added to the assignment when the replicas goes online

• Type: Task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.3.0
• Component/s: controller
• Assignee: Jose Armando Garcia Sancio
• Reporter: Jose Armando Garcia Sancio
• Created: 25/Oct/19 00:06
• Updated: 25/Oct/19 00:06

Description

The controller code when modelling the replicas state machine allows for a replica to be added to assignment when going online from a new state. This should not be possible.

Replicas are added to a partition when creating a topic, creating a partition or reassigning a partition. Whether a replica goes online should not cause a replica to get added to the assignment.

The code that currently allows this is here: https://github.com/apache/kafka/blob/trunk/core/src/main/scala/kafka/controller/ReplicaStateMachine.scala#L194-L198

We should restructure the code so that that condition is not possible.