Retries & backoff

The retry middleware retries failed sends with exponential backoff. Output only.

output:
  middlewares:
    - retry: { max_attempts: 5, initial_interval_ms: 200, max_interval_ms: 10000, multiplier: 2.0 }
  kafka: { topic: "orders", url: "localhost:9092" }

From the copy CLI:

Attach the chain to --to, since retry is output-only:

--to 'kafka://localhost:9092?topic=orders|retry?max_attempts=5&initial_interval_ms=200'

What gets retried

Only Retryable and connection errors are retried; NonRetryable failures pass straight through. Once attempts are exhausted, the error is marked so a following dlq treats it as permanent.

Always pair retry with dlq

retry does not retain a message it gives up on — it hands the still-failing message on to be dropped, or to a following dlq. Put dlq after retry so it’s the outermost layer and captures the exhausted failures:

output:
  middlewares:
    - retry: { max_attempts: 3 }
    - dlq: { endpoint: { file: { path: "rejected.jsonl" } } }

Don’t over-tune

Several endpoints already retry connection/timeout errors internally, and the retry middleware adds backoff on top — so you rarely need a large max_attempts. Cap max_interval_ms to match your latency budget so retries never stall a route indefinitely. See Performance tuning → Retry & backoff.