Idempotency violation with modern kafka clients #3039
Description
Version & Environment
Redpanda version: all versions up to 21.10.2
What went wrong?
Currently Redpanda doesn't do de duplication and returns OutOfOrderSequenceException when it suspects and an out of order record. Modern clients consider it as a non fatal error, bumps an epoch, resets seq number and retries the request. As a result in case of a network isolation (client <-> leader) or an leader termination (kill -9) a record may be produced twice.
What should have happened instead?
Redpanda should do de duplication or at least return a fatal error to force a user to close and recreate a producer