Power grids are transitioning from an infrastructure model based on reactive electronics towards a smart grid that features complex software stacks with intelligent, pro-active and decentralized control. As the power grid infrastructure becomes a platform for software, so does the need for a reliable roll-out of software updates on a large scale. In order to validate resilient large-scale software roll-out protocols, corresponding test beds are needed, which mirror not only ICT networks, but also include the actual software being deployed, and show the interaction between the power grid and the ICT network during the roll-out, and especially during roll-out failures. In this paper, we describe the design implementation of a large-scale co-simulation test bed that combines ICT and power grid simulators. We pay specific attention to the details of integrating containerized software in the simulation loop.