Abstract-Deployment of a service-oriented system in a network of machines is often complex and labourious. In many cases components implementing a service have to be built from source code for the right target platform, transferred to the right machines with the right capabilities and activated in the right order. Upgrading a running system is even more difficult as this may break the running system and cannot be performed atomically. Many approaches that deal with the complexity of a distributed deployment process only support certain types of components or specific environments, while general solutions lack certain desirable non-functional properties, such as atomic upgrading. This paper shows Disnix, a deployment tool which allows developers and administrators to reliably deploy, upgrade and roll back a service-oriented system consisting of various types of components in a heterogeneous environment from declarative specifications.