What’s special about Puppet’s model-driven design?
Traditionally, managing the configurations of a large group of computers has meant a series of imperative steps; in its rawest state, SSH and a for loop. This general approach grew more sophisticated over time, but it retained the more profound limitations at its root. Puppet takes a different approach, which is to model everything — the current state of the node, the desired configuration state, the actions taken during configuration enforcement — as data: each node receives a catalog of resources and relationships, compares it to the current system state, and makes changes as needed to bring the system into compliance. The benefits go far beyond just healing the headaches of configuration drift and unknown system state: modeling systems as data lets Puppet simulate configuration changes, track the history of a system over its lifecycle, and prove that refactored manifest code still produces the same system state. It also drastically lowers the barrier to entry for hacking and extendi
