Here at the OERu, we provide a service, attached to all of our online courses (and available to all of our partners - or anyone else for that matter) which allows anyone involved in those courses to communicate with one another from any one of a dazzling array of online "places" with WikiEducator Notes (aka WEnotes). The entire system is free and open source software (FOSS).
A few months back, I posted instructions on deploying Rocket.Chat and Wekan instances (and their mutual dependency, MongoDB) individually. Since then, I've spent some time with Docker Compose, a set of scripts which help you to define, build, and manage a set of Docker containers. Docker Compose is a thing of beauty. This is the way I now deploy Rocket.Chat, Wekan, and MongoDB together.