Promise-Theory

Mark Burgess shipped CFEngine in 1993, formalized promise theory with Siri Fagernes around 2005, and published In Search of Certainty in 2015. The model is precise: autonomous agents observe their environment, reason locally about what they find, and make promises about their own behavior. The agent does not receive instructions from a controller. The agent looks around, decides what to do, and commits to doing it. Every infrastructure tool since has claimed some lineage from this idea. Chef called its resources “convergent.” Puppet called its catalogs “desired state.” Terraform called its plans “declarative.” Ansible called its playbooks “idempotent.” ...

Every Terraform file you ever wrote was a note to a blind tool. You looked at your infrastructure, decided what it should be, wrote that decision into HCL, and handed it to a program that could not see for itself. The declaration was your observation, pre-computed and frozen into a file. The same was true for Chef recipes, Puppet manifests, and CFEngine promises. You observed the system. You wrote down what you saw and what you wanted. You gave that note to an agent that could parse files but could not look around. ...