Rudder is 100% open source.
Rudder is the only open source automation solution that includes an administration web interface, thanks to which you only need a few clicks to deploy your configuration rules, never being forced to write code. Indeed, a ready for use rules library is built in.
You think you are going to face very specific issues for which ready to use built in rules will not fit. You are right. However, Rudder will not let you fall back into developement. A graphical custom rules creation module is built in the solution.
Made for production issues, Rudder go beyond deployment instructions. It verifies and keeps proactively your IT desired state in order to stay compliant.
Rudder is able to manage every type of infrastructure, physical servers as virtual machines, open source OS (redhat, debian, suse, ubuntu, smartOS, android...) as licensed ones (Windows, AIX, UNIX...).