One of the great things about the Pantheon platform is that it provides a very easy way to apply updates to your Drupal sites. All that you need to do is navigate to the dashboard for your site, and if there have been any new releases for Drupal core, you will be able to see an "Apply Updates" button. Just click this button, and you'll be ready to run some tests and deploy to production. For more information on this process, see Applying Upstream Updates in the Pantheon documentation.
Although the process of applying updates on Pantheon is very easy, it is none the less different than the drush pm-update workflow that many Drupal users have become accustomed to using. If you use Drush to update a local copy of a Pantheon-hosted Drupal site, it will cause operational problems when the code is pushed up to the platform, and additional work will need to be done to back out the change. To make things easier on users, Pantheon is working on some improvements to the integration between the Pantheon platform and the Drush update workflow.
Today, as an initial interim step, Pantheon deployed a new file to the upstream repositories for Drupal 6, 7 and 8 on the Pantheon platform. This new file looks like this:
Do not update via Drush. See: https://pantheon.io/docs/articles/sites/code/applying-upstream-updates/
This file will have no effect for users of contemporary versions of Drush; however, if you upgrade to Drush 7.0-rc1, released last week, then the presence of this file will act as a guard against inadvertaint updates of Drupal core by Drush. If you run drush pm-update, then you will see the following notification:
|Locked Notification Message in Drush|
This is just the first step; keep an eye out for future updates that will pick up Drush update requests, and automatically pull in the right code for the Pantheon platform. The ultimate goal is to allow remote Drush updates of sites on the Pantheon platform, without any extra or special steps required on the part of the user. Stay tuned.