/sbin/tini ends up running the Sass compiler, which seems to need a larger thread stack size than the musl default. This patch incorporates a fix from https://raw.githubusercontent.com/jubel-han/dockerfiles/master/common/stack-fix.c, as described in https://github.com/sass/node-sass/issues/2031.
- improve docker_entrypoint.sh - serve static files with puma by default - sort packages list - use virtual package for build deps - show how to assign UID/GID