adamwiggins/12factor — pull request #9 by moredip (2012-02-10 06:43:08+00:00)
Title: Devs can also use virtual envs to get closer parity with prod

I added the following sentence:

Alternatively, declarative provisioning tools such as Chef and Puppet combined with light-weight virtual environments such as Vagrant allow developers to run local environments which closely approximate production environments.