How do you configure the consumer to start from the beginning for a new application deployment?

For the first deployment of a new consumer group, set spring.kafka.consumer.auto-offset-reset=earliest. This starts from offset 0. For subsequent deployments (same group-id), the committed offsets take precedence over auto-offset-reset (reset only applies when no committed offset exists). If you want to force re-read all messages: delete the consumer group first (kafka-consumer-groups.sh --delete --group my-group) or reset offsets manually. Be careful: auto-offset-reset=earliest on a running group with committed offsets has NO effect.

Expected key concepts: auto-offset-reset, earliest, new consumer group, committed offsets, group-id, delete consumer group, reset offsets, first deployment, subsequent deployments