Docker, actually Linux containers uses cgroup, which only isolates and priorities the resource usages, the overhead is very very low, so it does not matter much

Docker, actually Linux containers uses cgroup, which only isolates and priorities the resource usages, the overhead is very very low, so it does not matter much where it is used. The point of docker is allowing you to deploy your images, or more adequately put Dockerfiles on anywhere. So, when you have a Rpi cluster, you would worry less about deployment.