It's neat that beluga is written predominantly in bash but it's also difficult to see what Beluga actually does. Right now it looks like it sets up an environment for a docker compose app to run. Similar to docker machine but also solvable by tools like ansible, salt or python fabric. Kubernetes and Mesos are solving different problems. They manage and orchestrate services and add ons may also help with repository management.
My view may come from a lack of understanding of the tool's primary use case. Deeply interested in new developments in the docker ecosystem. Could you please update your current documentation with a few examples.