I now use ansible for provisioning to a mix of customer owned hardware, linode and digitalocean systems, previously experimented with saltstack. I use capistrano for deployment of the rails code, but am aiming at transitioning everything to ansible.
Recommended links:
- railsbox.io - “railsbox helps you to start applying best DevOps practices in your project by generating ansible playbooks for configuring and deploying Ruby on Rails applications. You no longer need to edit a single configuration file on your server and use tools like capistrano for code deployments - all this comes out of the box.”
- http://valdhaus.co/books/taste-test-puppet-chef-salt-stack-ansible.html - A good intro to the variety of tools (updated to include docker).
- http://itrevolution.com/books/phoenix-project-devops-book/ - The Phoenix Project: A Novel About IT, DevOps, and Helping Your Business Win
(and Grrrrr at 2 link limit 
)