KIP-909 — DNS Resolution Failure Should Not Fail the Client

Accepted Kafka 4.3 Client

Changes Kafka client construction to tolerate transient DNS resolution failures by deferring the fatal ConfigException and retrying resolution in the background during the connection establishment phase. A client whose bootstrap.servers hostname cannot be resolved at construction time immediately throws a ConfigException and dies, even if the DNS entry is about to become available—an especially severe problem in containerized environments with slow DNS propagation.

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