There are many Docker orchestration tools. If you're looking to set up a fully elastic Docker cluster on DigitalOcean you can check out the infrastructure as a service capabilities in DCHQ.
http://dchq.co/docker-digitalocean.html
It seems that there's a meetup coming up on this topic as well.
http://www.meetup.com/DCHQs-Docker-Meetups/events/228712311/