title: Maintenance mode using S3 + CloudFront
body: <p>I'm serving a single page app that is hosted on S3 and exposed to the web via CloudFront. When I'm performing maintenance on my API, I'd like to have a manual switch that causes the request to my app to render a maintenance page.</p>
  
  <p>I can put the maintenance HTML (or json) to the S3. How to configure CloudFront to return the maintenance site when I switch the maintenance mode on?</p>