I maintain over 50 roles on Ansible Galaxy, and a few dozen more locally. Since I run both CentOS (a RedHat derivative) and Ubuntu/Debian-based servers, I like to have a reliable platform to test my roles and playbooks everywhere with minimal effort. On GitHub, I generally use Travis CI to run a minimal set of tests against the Travis CI environment (currently Ubuntu 12.04). I wrote about this setup on the Server Check.in Blog: Testing Ansible Roles with Travis CI on GitHub. It's impossible to bootstrap extra test VMs inside the Travis environment due to Travis' use of OpenVZ. Thus, to run Ansible playbooks against CentOS and other versions of Ubuntu, I have to rely on a local configuration.