Same CloudTrail event triggering (using EventBridge Rule) Lambda function many times

Question

Hello, could someone explain to me why the same **CloudTrail event** is triggering a Lambda function multiple times (using an EventBridge rule)? The curious thing is that it doesn't always happen; sometimes the same type of event only executes the Lambda once. Here is the EventBridge rule:

{
  "source": ["aws.ecs"],
  "detail-type": ["AWS API Call via CloudTrail"],
  "detail": {
    "eventSource": ["ecs.amazonaws.com"],
    "eventName": ["SubmitTaskStateChange"],
    "requestParameters": {
      "cluster": [{
        "prefix": "XYZ"
      }],
      "status": ["PENDING"]
    }
  }
}

Thank you!

Riku_Kobayashi · Accepted Answer

Hello.

I think this is normal behavior since EventBridge may occasionally be executed multiple times.  
https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-troubleshooting.html#eb-rule-triggered-more-than-once  
> In rare cases, the same rule can run more than once for a single event or scheduled time, or the same target can be invoked more than once for a given triggered rule.

You can tell if the same event is being called by looking at the ID contained in the event.  
If this ID matches, you can determine that it is the same rule.

Same CloudTrail event triggering (using EventBridge Rule) Lambda function many times

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