I was recently doing some work on a site hosted on Pantheon and came across an issue, for which part of the suggested fix was to ensure that the $base_url variable was explicitly defined within settings.php (this is also best practice on all Drupal sites).

The way that was recommended was by using a switch() function based on Pantheon's environment variable. For example:

Tags:

• Drupal Planet
• Pantheon
• settings.php
• Drupal