Alpine Linux is an independent, non-commercial, general purpose Linux distribution designed for power users who appreciate security, simplicity and resource efficiency. In my opinion it has become very popular thanks to Docker momentum, because it has a small footprint and is optimized to be run in RAM.
There is official documentation explaining how to install Alpine Linux on a Raspberry Pi. However, I prefer to use Alpine Linux inside dockerized environments and to use Raspbian based on the popular and mature Debian Jessie as OS host on the Rasperry Pi.
I would like to document two techniques for dockerize Linux Alpine and to describe how can be used on your Raspberry Pi. With this documentation you are going to be able to ensure better resource consumptions of docker containers on your Pi.