Charon: Declarative provisioning and deployment

We introduce Charon, a tool for automated provisioning and deployment of networks of machines from declarative specifications. Building upon NixOS, a Linux distribution with a purely functional configuration management model, Charon specifications completely describe the desired configuration of sets of “logical” machines, including all software packages and services that need to be present on those machines, as well as their desired “physical” characteristics. Given such specifications, Charon will provision cloud resources (such as Amazon EC2 instances) as required, build and deploy packages, and activate services. We argue why declarativity and integrated provisioning and configuration management are important properties, and describe our experience with Charon.