Create Image for standalone QGIS2 App

I am having trouble to build a docker image of a QGIS2 standalone app.

I tried to download a qgis2 image from the repository and write the app in the container, without success.
I would like now to use a docker-compose file to build the qgis2 app directly from my laptop, but I am having troubles in understanding how to define the Dockerfile and the docker-compose.yml file.

Can anybody help me?