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Conduktor Gateway data quality Interceptors validate Kafka messages at the proxy layer — before they hit the broker. Rules run per record and have three outcomes: block the message (error returned to the producer), mark it with a header so consumers can decide what to do, or redirect it to a dead-letter topic.

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When to use data quality interceptors

Use data quality interceptors when you need to:
  • Enforce schema contracts — reject records that don’t match an expected Avro, Protobuf, or JSON Schema
  • Apply business rules — validate field values using CEL expressions (e.g., age > 0, email not null)
  • Prevent bad data propagation — stop invalid records before they reach consumers and cause processing failures
  • Observe without blocking — audit violations in real time without interrupting producer traffic

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Available policies

PolicyUse case
Data quality policyCEL expression and JSON Schema validation on topic messages
Data quality producer policyValidate records at produce time before they are written to the topic
Schema payload validation policyEnforce that records use a registered Schema Registry schema ID