title: How to use AWS Lambda to check file in S3
body: <p>Brand new to AWS Lambda so I'm not even sure if this is the right tool to accomplish what I'm trying to do.</p>
  
  <p>Basically what I'm trying to do is check if a file exists or if it was updated recently in S3.  If that file isn't there or wasn't updated recently I want an AMI to be cloned to an AWS instance.</p>
  
  <ol>
  <li>Is the above possible?</li>
  <li>Is Lambda the right tool for the job?</li>
  </ol>
  
  <p>I'm fairly competent in JavaScript but have never used node.js or Python so writing a Lambda function seems complex to me.</p>
  
  <p>Do you know of any resources that can help with building Lambda functions?</p>
  
  <p>Thanks!</p>