title: Verify that API call was made from AWS Lambda (or another server)
body: <p>Is there any way I can check that a call is made from an expected lambda function or you can consider it as another server. </p>
  
  <p>The use case is: I want to emit a websocket event to notify my web app when my EC2 status changes. (Do suggest a better way if any) My web socket server will be an EC2 instance. So I am wondering, if there is some way to allow calls to this specific API to be only from a valid AWS Lambda function? </p>
  
  <p>Currently I am thinking maybe I can just use a shared secret ... but since this never expires, wonder if its a security risk? </p>
  
  <p><strong>UPDATE</strong></p>
  
  <p>A thought came to mind, isit ok to use asymmetric encryption like RSA for this? </p>
  
  <p>Oh wait, is RSA not suitable for such data encryption? I read its for signing keys? </p>