Status

Current state: Under Discussion

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

Motivation

In KIP-444 we refactored the structure of the built-in metrics in Streams. In order to allow users to still use the old metrics structure, we introduced the Streams config built.in.metrics.version with values 0.10.0-2.4 and latest. Maintaining the code for the old and the new structure of the built-in metrics is error-prone and probably not necessary anymore since enough time passed since KIP-444 was released. Moreover, new metrics that were added after KIP-444 only conform to the new structure, so that if users still rely on the old built-in metrics structure they have to deal with a mix of the old and the new structure.

We propose to deprecate the config value 0.10.0-2.4 for Streams config built.in.metrics.version in AK 4.0 and remove the config value in 4.0.

Public Interfaces

/**
 * Config value for parameter {@link #BUILT_IN_METRICS_VERSION_CONFIG "built.in.metrics.version"} for built-in metrics from version 0.10.0. to 2.4
 * 
 * @deprecated Since 3.0.0, will be removed in 4.0.
 */
@Deprecated
public static final String METRICS_0100_TO_24 = "0.10.0-2.4";

Proposed Changes

We plan to deprecate value 0.10.0-2.4 of config built.in.metrics.version in AK 3.0.0 and to remove it in AK 4.0.

Since some users may skip the StreamsConfig and set the string value of 0.10.0-2.4 directly, we will also log a warning if the config value is detected to raise the visibility for users who may have missed the deprecation.

Compatibility, Deprecation, and Migration Plan

Config value 0.10.0-2.4 of config built.in.metrics.version will be deprecated in AK 3.0.0 and will be removed in AK 4.0.

Rejected Alternatives

• Removing the complete config built.in.metrics.version: The config can still be used for future changes to the built-in metrics.