How to trigger a Lambda on S3 file upload

Question

I can't seem to get my lambda to trigger as I would expect. In AWS EventBridge, I created a rule with the following custom event pattern:

{
  "source": ["aws.s3"],
  "detail-type": ["AWS API Call via CloudTrail"],
  "detail": {
    "eventSource": ["s3.amazonaws.com"],
    "eventName": [
      "CopyObject",
      "CompleteMultipartUpload",
      "PutObject"
    ],
    "requestParameters": {
      "bucketName": ["my-bucket"],
      "key": [{"prefix": "folder1/folder2/"}]
    }
  }
}

but when I upload a file to the "directory" the rule does not trigger the lambda.

Can someone tell me where I've gone wrong?

Answer 1

Thanks to all for the help and suggestions - all good resources should someone come across this post in the future. Turns out in my case @Balu Vyamajala was correct in the comments - I had incorrectly configured CloudTrail.