Support npm/yarn projects

[judithhartmann]

Hey,
I would like to use this docker image in a gitlab pipeline for our npm based project. Unfortunately when I run it against the yarn.lock it tells me, no yarn executable could be found.

I tried to install it myself if the gitlab pipeline, but i did not find a way to install things through apk as i can't switch to root user in the pipeline and the docker switches to a non root user in the end.

Could you install node and yarn in the docker image?