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

Kafka clients report warning for config options that were not used during initialization, for example, a default set of warnings you get when starting Streams application:

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This list can be extended if you use some extra configuration, required by your internal infrastructure or if you use some 3rd party plugins. While these config options are valid they create a lot of noise in monitoring. This KIP proposes to make behavior configurable when unknown configs are being processedsuppress this warning by changing its log level to DEBUG.

Public Interfaces

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None.

Proposed Changes

Add new config option "unused.config.reporter.class" to AbstractConfig. Add new interface UnusedConfigReporter, default implementation for this interface will mimic current behaviour (report warning).Change log level from WARN to DEBUG for unused config message.

Compatibility, Deprecation, and Migration Plan

It will be a transparent change, as a default behavior will produce the same result as we have todayNone. Hard to imagine a scenario where anyone relies on this message to be a warning.

Rejected Alternatives

Adding interface to control message log level

There are no strong reasons to keep it as a warning, so introducing an extra interface would be an overkill. 

Remove the warningmessage

The warning should stay, as it could save time debugging issues related to incorrect configuration.

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