This is the simplest Node.js + MongoDB docker possible config.
Simply copy Dockerfile and docker-compose.yml to your project and run docker-compose up.
By default the Node.js container will listen on port 7777, to change it edit the ports section of the web service in the docker-compose.yml file.
By default the MongoDB container will listen on port 27017, to change it edit the ports section of the mongo service in the docker-compose.yml file.