Status

Current state: Under Discussion",

...

Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

Motivation

In KIP-584, it introduced describeFutures Admin API to return supported and finalized features. Finalized features are consistent across the entire cluster, allowing users to receive the same response from any node. In contrast, supported features depend on unstable.api.versions.enable configuration, which can lead to different results from different nodes. This inconsistency can confuse users about the correct supported minimum and maximum versions within the cluster. Even if users are aware of this issue and want to check the supported version on a specific node, they currently cannot specify the node ID in the Admin API or CLI tool. This KIP proposes adding a new optional argument to the describeFeatures Admin API and FeatureCommand CLI tool, enabling users to retrieve supported features from a specified node.

Public Interfaces

DescribeFeaturesOptions

Add nodeId to DescribeFeaturesOptions. Default value is -1.

public class DescribeFeaturesOptions extends AbstractOptions<DescribeFeaturesOptions> {
    private int nodeId = -1;

    /**
     * Set the node id to which the request should be sent. If using bootstrap controller and node id is less than 0,
     * the request will be sent to the controller node. If using bootstrap broker and node id is less than 0, the
     * request will be sent to the first available node.
     */
    public DescribeFeaturesOptions nodeId(int nodeId) {
        this.nodeId = nodeId;
        return this;
    }

    /**
     * The node id to which the request should be sent. If using bootstrap controller and node id is less than 0,
     * the request will be sent to the controller node. If using bootstrap broker and node id is less than 0, the
     * request will be sent to the first available node.
     */
    public int nodeId() {
        return nodeId;
    }
}

Proposed Changes

kafka-features.sh

describe —node-id <node-id>

Add —-node-id to kafka-features.sh describe command. The argument is optional. If the value is negative, throws IllegalArgumentException.

> ./bin/kafka-features.sh --bootstrap-server localhost:9092 describe --node-id 2
Feature: eligible.leader.replicas.version	SupportedMinVersion: 0	SupportedMaxVersion: 1	FinalizedVersionLevel: 0	Epoch: 153
Feature: group.version	SupportedMinVersion: 0	SupportedMaxVersion: 1	FinalizedVersionLevel: 1	Epoch: 153
Feature: kraft.version	SupportedMinVersion: 0	SupportedMaxVersion: 1	FinalizedVersionLevel: 1	Epoch: 153
Feature: metadata.version	SupportedMinVersion: 3.3-IV3	SupportedMaxVersion: 4.0-IV3	FinalizedVersionLevel: 4.0-IV3	Epoch: 153
Feature: transaction.version	SupportedMinVersion: 0	SupportedMaxVersion: 2	FinalizedVersionLevel: 2	Epoch: 153
  
> ./bin/kafka-features.sh --bootstrap-controller localhost:9093 describe --node-id 1
Feature: eligible.leader.replicas.version	SupportedMinVersion: 0	SupportedMaxVersion: 1	FinalizedVersionLevel: 0	Epoch: 7
Feature: group.version	SupportedMinVersion: 0	SupportedMaxVersion: 1	FinalizedVersionLevel: 1	Epoch: 7
Feature: kraft.version	SupportedMinVersion: 0	SupportedMaxVersion: 1	FinalizedVersionLevel: 1	Epoch: 7
Feature: metadata.version	SupportedMinVersion: 3.3-IV3	SupportedMaxVersion: 4.1-IV0	FinalizedVersionLevel: 4.0-IV3	Epoch: 7
Feature: transaction.version	SupportedMinVersion: 0	SupportedMaxVersion: 2	FinalizedVersionLevel: 2	Epoch: 7

Compatibility, Deprecation, and Migration Plan

No breaking change is introduced. The new argument —-node-id is optional.

Test Plan

Admin API

• Default DescribeFeaturesOptions can work as usual.

• If nodeId is negative, the Admin client ignores it and falls back to use LeastLoadedBrokerOrActiveKController.

• If nodeId is valid, the Admin client sends ApiVersionRequest to a node with nodeId.

kafka-features.sh

• The empty —-node-id can work as usual.

• If nodeId is negative, throws IllegalArgumentException.

• If nodeId is valid, the FeatureCommand get ApiVersionResponse from a node with nodeId.

Rejected Alternatives

N/A