[KAFKA-8619] Allow instances to be passed instead of Classes or Strings for configuration

• Type: Wish
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Fix Version/s: 2.3.0
• Assignee: Unassigned
• Reporter: Graeme Rocher
• Created: 01/Jul/19 11:12
• Updated: 01/Jul/19 11:15

Description

The getConfiguredInstances method of AbstractConfig currently forces values to be either a Class instantiated directly by Kafka or a String that uses dynamic classloading.

This limits how DI systems can integrate with Kafka since if you want to inject an existing Spring, Micronaut, Guice etc. bean to for example by your Metrics reporter then there is no way to do that currently.

What would be useful is if a simple statement such as:

if (t.isInstance(klazz))  {
    o = klazz;
}

Could be added here:

https://github.com/apache/kafka/blob/53b837f9c604cdb8a5a77a9363fc058b9ef9cd7e/clients/src/main/java/org/apache/kafka/common/config/AbstractConfig.java#L421

This would make it possible to specify instances that are not instantiated by Kafka.