- Simplified inventory management: Well, yes. Drush can be called locally and initiate tasks on remote server when provided with the right parameters. However, if all that was done through Ansible, the inventory would only have to be maintained for Ansible and not for Drush as well.
- Better performance: Ansible is really optimized to get connections established and tasks initiated on remote servers including all the permission management and other overhead. Drush does it as well, but Ansible is focusing on this area.
- Parallel execution: with Ansible as the master, Drush commands could be executed on many hosts at once where Drush is only designed to work in a series.
- Installing and upgrading Drush
- Managing inventory and facts:
- Determine Drupal root directories
- Create and maintain alias lists
- Feed all those details back into the facts for Ansible and make them available for subsequent Drush calls
- Executing Drush commands
- d.o Vagrant Ansible: https://drupal.org/sandbox/franskuipers/1801378
- ansible-drush role: https://github.com/thecarlhall/ansible-drush
- Drupal Host using both, Drush and Ansible: https://www.xplainhosting.com/contact-us
- Four Kitchen: http://fourkitchens.com/tags/open-source
- dbuild.py: http://devblog.more-onion.com/building-multi-sites-dbuildpy
Coding Standards: https://github.com/ansible/ansible/blob/devel/CODING_GUIDELINES.md