You don't need to use node to serve a harp site - you can just compile the files and use anything -
This is a container that has node and harp available, to compile and install the static site, that nginx serves.
You can use our container:
docker pull xorcode/harp-nginx
Or you can build your own:
docker build -t your-name-here/harp-nginx . docker push your-name-here/harp-nginx
After this - just add this Dockerfile to your Harp repo:
FROM xorcode/harp-nginx WORKDIR /srv/www ADD . /srv/www/ RUN harp compile EXPOSE 80 CMD nginx
Push it to your docker server - and your server will use 4-6MB of RAM instead of 60MB.
To see an example working repo, take a look here.