Part of croudfront settings for drupal7

/**
 * @file
 * AWS configuration file.
 */

if (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] == 'on') {
  $base_root = 'https';
}
// We're behind a proxy that talks to the web server via HTTP.
elseif (isset($_SERVER['HTTP_X_FORWARDED_PROTO'])) {
  $base_root = $_SERVER['HTTP_X_FORWARDED_PROTO'];
}
elseif (isset($_SERVER['HTTP_CLOUDFRONT_FORWARDED_PROTO'])) {
  $base_root = $_SERVER['HTTP_CLOUDFRONT_FORWARDED_PROTO'];
}
// There's no HTTPS spoor -- we must be running HTTP.
else {
  $base_root = 'http';
}

if (!empty($_SERVER['HTTP_X_FORWARDED_PROTO'])) {
  $http_host = $_SERVER['HTTP_X_FORWARDED_HOST'];
}
else {
  $http_host = $_SERVER['HTTP_HOST'];
}

$base_url = $base_root .= '://' . $http_host;