[jira] [Created] (KAFKA-18523) Improve default.replication.factor docs

["Matthias J. Sax (Jira)" <ji...@apache.org>]

Matthias J. Sax created KAFKA-18523:
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             Summary: Improve default.replication.factor docs
                 Key: KAFKA-18523
                 URL: https://issues.apache.org/jira/browse/KAFKA-18523
             Project: Kafka
          Issue Type: Task
          Components: docs
            Reporter: Matthias J. Sax


We had a user report, that the `default.replication.factor` was not picked up correctly by a KafkaStreams app, which by default uses `-1` as client side config for `replication.factor` when creating internal topics.

Turns out, that there seems to be a difference between "regular brokers" and "controller nodes" in KRaft. This is not clear from the docs.

From the user:
{quote}Although the config setting {{default.replication.factor}} is listed under "Broker configuration" in the Kafka docs, digging in the Kafka source code revealed that the {{-1}} value is actually mapped on the controllers, not the "normal" brokers. Adding {{default.replication.factor}} to the controllers as well, resolved the problem.
{quote}
Would be great to improve the docs accordingly. Not sure if this might apply to other configs, too.



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