Service configuration management

The deployment of services --- sets of running programs that provide some useful facility on a system or network --- is typically implemented through a manual, time-consuming and error-prone process. For instance, system administrators must deploy the necessary software components, edit configuration files, start or stop processes, and so on. This is often done in an ad hoc style with no reproducibility, violating proper configuration management practices. In this paper we show that build management, software deployment and service deployment can be integrated into a single formalism. We do this in the context of the Nix software deployment system, and show that its advantages --- co-existence of versions and variants, atomic upgrades and rollbacks, and component closure --- extend naturally to service deployment. The approach also elegantly extends to distributed services. In addition, we show that the Nix expression language can simplify the implementation of crosscutting variation points in services.