You can basically do this with the "building" gem: https://github.com/CenturyLinkLabs/building
It uses Heroku buildpacks to build self-contained containers with all your dependencies with one command: building containername
Dokku is great, and has a PG plugin:
https://github.com/progrium/dokku
https://github.com/Kloadut/dokku-pg-plugin
DO has a Dokku vm you can select when you spin up a new droplet.
Chef-solo is probably more up your alley. You should be able to easily find recipes for Postgres, Nginx, RVM/rbenv, etc. to automate the building of the server.
Try https://www.cloud66.com/, it does what you want, but for some money.
Re:Peas: Ruby-based Docker PaaS
by michaelbuckbee on Sunday April 06, 2014 @12:48PM
(#7541506)
Cloud66 is kind of incredible, I was an early beta tester for them and they really are hitting an interesting price/value point wrt managing complex systems.
Then I can deploy with a single command?
I have done this a ton of times with Capistrano but it's always a pain in the ass for new projects because I need to install Nginx, PostgreSQL, RVM, Ruby version, etc etc etc. Lots of busywork I don't really care about.