If one of the services is unavailable during enrichment (for example, the service with the user's full name/data), what happens? Does the entire Kafka stop?

If during data enrichment one of the services, such as a service with full name or user data, is unavailable, it does not cause the entire Kafka to stop. Kafka as a messaging system continues to operate because it is separated from the data processing and enrichment logic.

What happens in practice:

• A consumer that reads messages from Kafka and calls the enrichment service may encounter an error or timeout when accessing the unavailable service.
• Depending on the implementation, the consumer may:
  • Log the error and skip enrichment for this message,
  • Retry with exponential backoff,
  • Send the message to a DLQ (Dead Letter Queue) for later analysis,
  • Pause message processing if it is critical.

Thus, the failure of one service does not stop Kafka but may affect message processing in a specific consumer. To ensure system resilience, it is recommended to implement error and timeout handling, as well as use resilience patterns such as Circuit Breaker.