boost-bootstrap-adapter-kafka

REQUIRED BACKGROUND:

• boost-bootstrap-function — handler typing rule.
• boost-bootstrap-middleware — recovery/logger/publisher chain.
• boost-extra-middleware — NewAnyErrorWrapper for the workaround.
• boost-bootstrap-adapter-pubsub — same shape, full workaround pattern documented there.

Canonical (prototype / dev)

import (
    akafka "github.com/xgodev/boost/bootstrap/function/adapter/contrib/confluentinc/confluent-kafka-go/v2"
    "github.com/xgodev/boost/bootstrap/function"
)

fn, _ := function.New[*cloudevents.Event](rec, lmi, pmi)
fn.Run(ctx, handle, akafka.New[*cloudevents.Event](consumer))

Topics, consumer group, broker list, and offset reset behavior are configured via boost.bootstrap.function.adapter.kafka.* (override via BOOST_BOOTSTRAP_FUNCTION_ADAPTER_KAFKA_*).

Production caveat — same ctx-loss as Pub/Sub

bootstrap/function/adapter/contrib/confluentinc/confluent-kafka-go/v2/helper.go:41 hard-codes:

err := subscriber.Subscribe(context.Background())

SIGTERM does not gracefully drain in-flight messages. Apply the same workaround pattern documented in boost-bootstrap-adapter-pubsub: bypass fn.Run, build the chain via extra/middleware.NewAnyErrorWrapper, drive akafka.NewSubscriber with a signal-aware ctx, and add the // TODO(boost-upstream): annotation naming the offending file.

Consumer group semantics

Kafka delivers each message to exactly one member of a consumer group. The boost adapter respects the group config — set boost.bootstrap.function.adapter.kafka.groupID so multiple replicas of your service share the partition load.

Offsets commit on successful handler return (post-publisher middleware). A handler error propagates as a nack — the message replays per Kafka's redelivery semantics. Wrap errors via bootsterrors.Wrap (see boost-model-errors) so the deadletter middleware can route by type.

Red flags

Red flag	Fix
kafka.Consumer.Poll(...) / ReadMessage(...) loops directly	Use akafka.NewSubscriber(...).Subscribe(ctx) or function.New + fn.Run
Bypass of fn.Run without // TODO(boost-upstream): naming helper.go:41	Add the comment, OR accept ungraceful shutdown
Reading KAFKA_BROKERS / KAFKA_GROUP_ID via os.Getenv	Use BOOST_BOOTSTRAP_FUNCTION_ADAPTER_KAFKA_* overrides
Manual offset commit inside the handler	Let the publisher middleware drive commit on success (default)