Working with Magento SSL behind a Load Balancer

index.php

/**
 * EC2's load balancer sets these for us so we know we're secure,
 *  preventing Magento from performing a redirect loop.
**/
if( isset($_SERVER['HTTP_X_FORWARDED_PROTO']) ) {
    $_SERVER['HTTPS'] = 'on';
    $_SERVER['SERVER_PORT'] = 443;
}