DEN stands for "Docker Environment for Node.js" and it's a basic skel project to have a dockerized development environment

docker-compose up --build will build the docker image based on the Dockerfile

The Dockerfile itself will get packge*.json, copy them in the image and run npm install then run npm run dev (it's a npm script that now run nodemon server.js).

To use your package manager (npm, yarn or whatever) you must enter the running image and execute every commands there instead of trying to do it from the host itself.

This should provide an out fo the box environment to develop node.js app without even have node installed on your machine.

Right now the port 8080 will be exposed on the host and a /ping endpoint will return the string pong