title: What's the best strategy to monitor S3 bucket for missing a new file in the last x hours?
body: <p>I have a use case where some process puts a file every 6 hours to an S3 bucket. This bucket has already thousands of files in it and I wanted to generate an sns alert or something if no new file is added in the last 7 hours.  what would be a reasonable approach?
  Thanks</p>