Jonge. Atomic upgrading of distributed systems

Upgrading distributed systems is a complex process. It re-quires installing the right services on the right computer, configuring them correctly, and so on, which is error-prone and tedious. Moreover, since services in a distributed sys-tem depend on each other and are updated separately, up-grades typically are not atomic: there is a time window dur-ing which some but not all services are updated, and a new version of one service might temporarily talk to an old ver-sion of another service. Previously we implemented the Nix package management system, which allows atomic upgrades and rollbacks on single computers. In this paper we show an extension to Nix that enables the deployment of distributed systems on the basis of a declarative deployment model, and supports atomic upgrades of such systems. 1