Regardless of tools, I see two features as essential: agentless clients + programmable dsl. As far as I know, no such tool exists (would love to be proven wrong

Regardless of tools, I see two features as essential: agentless clients + programmable dsl. As far as I know, no such tool exists (would love to be proven wrong). Ansible relies on SSH only, which is pretty much a must on 99,9% servers anyway, but its language (and philosophy) is purely declarative. At the moment you need anything generic, abstracted into functions, you are in trouble. (Believe me, you don't want to be hacking stuff into Yaml, it's a mess). Chef is the opposite: you have access to a Turing complete language, but you need an overly complex server architecture along with running agents on all nodes. Merge Ansible's ssh client with Chef's programmable dsl and you probably have something huge there.