AWS eventbridge: Clarify FIFO ordering limits for Lambda EVENT vs REQUEST_RESPONSE
Summary
Adds a note that a FIFO subscriber accepts InvocationType EVENT for Lambda targets but ordering holds only to the hand-off into Lambda's async queue, recommending REQUEST_RESPONSE; also softens the earlier claim of 'exactly-once delivery' to 'exactly-once ingestion'.
Security assessment
The change is about event ordering/duplicate-delivery semantics, not a security control; no auth, encryption, or vulnerability information is involved.
Evidence
+A FIFO subscriber accepts `InvocationType` `EVENT` for a Lambda target, but order then holds only up to the hand-off into Lambda's asynchronous queue. Use `REQUEST_RESPONSE` for ordered processing.
Diff
diff --git a/eventbridge/latest/userguide/eb-custom-bus-ordering.md b/eventbridge/latest/userguide/eb-custom-bus-ordering.md index d6893478a..93f7bc858 100644 --- a//eventbridge/latest/userguide/eb-custom-bus-ordering.md +++ b//eventbridge/latest/userguide/eb-custom-bus-ordering.md @@ -20,0 +21,2 @@ Within a FIFO subscriber, an event that cannot be delivered holds up the later e +A FIFO subscriber accepts `InvocationType` `EVENT` for a Lambda target, but order then holds only up to the hand-off into Lambda's asynchronous queue. Use `REQUEST_RESPONSE` for ordered processing. + @@ -34 +36 @@ EventBridge suppresses a duplicate that arrives within 5 minutes (300 seconds) o -Together, this gives exactly-once delivery: a duplicate publish within the window is suppressed at the bus, and a FIFO subscriber then delivers each accepted event once, in order, within its group. Outside the window, or from a different account or group, a repeated publish is a new event. Keep consumers idempotent for those cases. +Together, this gives exactly-once ingestion: a duplicate publish within the window is suppressed at the bus, and a FIFO subscriber then hands each accepted event to its target once, in order, within its group.