Does AWS CloudWatch Events Rule supports any wildcards in S3 bucket/key names

The template code gave by Marto was not working for me, however the doc led to a solution:

{
  "source": ["aws.s3"],
  "account": ["1111111xxxxx"],
  "detail": {
    "eventSource": ["s3.amazonaws.com"],
    "eventName": ["PutObject"],
    "requestParameters": {
      "bucketName": ["mybucket"],
      "key": [{"prefix": "myfile-*"}]
    }
  }
}

Hope it helps.

I found a fancy solution for this using Content-based filtering (released in February 2020) like prefix for example.

So in your case, the solution should be:

{
  "source": ["aws.s3"],
  "account": ["1111111xxxxx"],
  "detail": {
    "eventSource": ["s3.amazonaws.com"],
    "eventName": ["PutObject"],
    "requestParameters": {
      "bucketName": ["mybucket"],
      "key": [{ "prefix": "myfile-" }]
    }
  }
}