Hi! Thank you for the Apache Kafka! We are grateful for it.
In our root cause analysis process discussions, we were asked to share following piece of information to the Apache Kafka community. Following is a known topic, in generic, it seems, already. E.g. there are existing tickets, and Uuid.java implementation already handles the "problem", in one way. Following was still asked to be raised up. Kafka cluster ID does not work exactly as it is defined in documentation of Apache Kafka. ( Those are not exactly in sync. ) Regarding location of one character. In the documentation of Apache Kafka, hyphen, "-" is allowed to be in the beginning, according to the exact definition and regexp: https://kafka.apache.org/documentation/ Quotation: "The cluster id ... the allowed characters are defined by the regular expression [a-zA-Z0-9_\-]+". According to that, hyphen, "-", is allowed to be in the beginning of the value of cluster ID. But that is incorrect. In reality, the Apache Kafka instance / cluster does not start up with hyphen "-" in the beginning of the value of the cluster ID. The problem: kafka-storage could not parse command line argument ( cluster ID ). There comes an error: "argument --cluster-id/-t: expected one argument" More: It seems to be a known issue in Apache kafka. Because there exists following source codes / function: ... * This will not generate a UUID equal to 0, 1, or one whose string representation starts with a dash ("-") */ public static Uuid randomUuid() { Uuid uuid = unsafeRandomUuid(); while (RESERVED.contains(uuid) || uuid.toString().*startsWith*("*-*")) { uuid = unsafeRandomUuid(); } return uuid; } } https://fossies.org/dox/kafka-3.8.0-src/Uuid_8java_source.html https://github.com/apache/kafka/blob/trunk/clients/src/main/java/org/apache/kafka/common/Uuid.java https://issues.apache.org/jira/browse/KAFKA-13741 An other older ticket related to UUID / cluster ID starting with "hyphen": https://issues.apache.org/jira/browse/KAFKA-15754 We generated/generate the cluster ID in our own function. And that caused trouble. Best Regards Sam
