I've put up a Dockerfile that builds the pharo.cog.spur.minheadless VM on Alpine Linux within Docker. This allows one to build said VM without having to first create an Alpine Linux installation such as through VirtualBox.
https://github.com/pharo-contributions/Docker-Alpine/tree/master/vm.build This is a multi-stage Dockerfile. The Pharo VM is built in an Alpine Linux 'build' container. Then the VM files are copied into a fresh Alpine Linux Docker image. The resulting Pharo VM Docker image is ~14 MB. The output Docker image contains the Pharo VM only and is not runnable by itself. It is intended to be used as a base to build your own Docker image containing your application-specific Pharo image. Tested on Ubuntu 18.04 and MacOS Mojave. Pierce
