Status

Current state: Under discussion

Discussion thread: https://lists.apache.org/thread/w4ml9ffkj1j31j8kjpbywq9jsw5ck5sr

JIRA: KAFKA-19254 - Getting issue details... STATUS

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Motivation

Currently, there exists a kafka.server:type=MetadataLoader,name=CurrentMetadataVersion  metric which tells the operator the metadata version feature level for every node in a cluster. However, now that there several features with support beyond the metadata.version  feature, adding a metric to display those features' levels would be helpful for monitoring upgrade/downgrade scenarios for clusters using those features.

Public Interfaces

Monitoring

Add a metric for each production feature (i.e. metadata.version , kraft.version , transaction.version , group.version , eligible.leader.replicas.version , share.version, and streams.version ).

This can be accomplished via one generic "feature level" metric that is tagged by feature. Using a generic metric allows for new production features to automatically expose their feature level going forward. 

This metric will report the finalized feature level for each production feature. If the feature level is not set, the metric will return a value of 0.

Compatibility, Deprecation, and Migration Plan

We will deprecate the kafka.server:type=MetadataLoader,name=CurrentMetadataVersion metric since this per-feature tagged metric also exposes this value, and the previous metric can be removed starting in 5.0.

Test Plan

We will add junit tests to verify the new metrics.

Rejected Alternatives

Running kafka-feature describe  on every node is one way to track feature level upgrades/downgrades, but it is not straightforward to monitor since it is not a metric.