title: Lambda processing same SNS event multiple times?
body: <p>I have an AWS Lambda function configured to process SNS events from a single topic. When the function runs it will potentially send out some other notifications and call context.succeed, or context.fail if some error occurs.
  The problem is the same SNS event seems to be invoking the Lambda multiple times. Looking at the CloudWatch logs I see</p>
  
  <p><code>START RequestId: cd7afdf8-2816-11e6-bca2-6f2e3027c5e1 Version: $LATEST</code></p>
  
  <p>Which eventually ends</p>
  
  <p><code>END RequestId: cd7afdf8-2816-11e6-bca2-6f2e3027c5e1 
  REPORT RequestId: cd7afdf8-2816-11e6-bca2-6f2e3027c5e1 ...</code></p>
  
  <p>Immediately followed in the same log by a start for the exact same RequestID</p>
  
  <p><code>START RequestId: cd7afdf8-2816-11e6-bca2-6f2e3027c5e1 Version: $LATEST</code></p>
  
  <p>Looking into CloudWatch at the topic sending this SNS Event it seems to only be Publishing and Delivering only one even as I had expected, so it seems to be a Lambda-side problem. Does anyone know of any reason an event might be triggering my lambda multiple times like this?</p>
  
  <p>Edit: I've noticed that this seems to be happening when the lambda receives a failure. I don't see any sort of retry configuration on the lambda and wouldn't expect it to be behaving this way by default.</p>