The momentum gained by the microservice-oriented architecture is fostering the diffusion of operating system containers. Existing studies mainly focus on the performance of con-tainerized services to demonstrate their low resource footprints. However, availability analysis of densely deployed container-based solutions is less visited due to difficulties in collecting failure artifacts. This is especially true when the containers are combined with virtual machines to achieve a higher security level. Inspired by Google's Kubernetes architecture, in this paper, we propose ContAv, an open-source distributed statistical model checker to assess availability of systems built on containers and virtual machines. The availability analysis is based on novel state-space and non-state-space models designed by us and that are automatically built and customized by the tool. By means of a graphical interface, ContAv allows domain experts to easily parameterize the system, to compare different configurations and to perform sensitivity analysis. Moreover, through a simple Java API, system architects can design and characterize the system behavior with a failure response and migration service.