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The target of my EventBridge rule is a Lambda function. While creating the rule, it was noticed that the default value for retry attempts is set at 185. If the function's concurrency limit is reached and the rule tries to send a new event to Lambda, I assume the event is throttled. Now, will EventBridge rule retry sending this throttled event to Lambda?

I conducted an experiment by setting the reserved concurrency to 5 and then simultaneously sending 7 events to the EventBus, all of which matched the same rule pattern. Interestingly, I observed that all 7 events were processed by Lambda. Initially, I assumed that an event was throttled at Lambda and the EventBridge rule retried, but then I discovered that asynchronous event invocations to Lambda are queued and some form of retry occurs when the function is throttled. I am curious: is my retry due to the Lambda retry policy or the EventBridge retry policy?

djmonki
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100ELL
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1 Answers1

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The retry you observed is due to Lambda's retry policy, not EventBridge's retry policy. When an event is throttled at a Lambda function due to reaching the function's concurrency limit, AWS Lambda will automatically retry the event. EventBridge, on the other hand, does not handle the retrying of events in this scenario.

Code_Sphinx_TSK
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  • thanks for the info, do you know if there is any way to make eventbridge retry when event gets throttled because for lambda max retry attempts that can be configured is 2, but for EventBridge its way higher – 100ELL Jul 25 '23 at 04:56
  • As of my knowledge, there is no direct way to configure EventBridge to retry when events get throttled. Retry behavior for throttled events is primarily handled by AWS Lambda's retry policies. – Code_Sphinx_TSK Jul 25 '23 at 06:01
  • Hey, i configured the retry attempts in asynchronous invocations to 0 in console, with reserved concurrency to 5 and i sent 10 events at once, now what i expected to happen is 5 events to be processed and 5 events throttled and unprocessed, but all 10 events got processed and i saw the throttle count in graph which was showing 29, this shouldn't happen if retry policy is handled by Lambda for throttled events unless this was taken care by EventBridge or am i missing something – 100ELL Jul 27 '23 at 17:20