I built CentOS and Ubuntu base boxes mainly as a starting point for people working through Efficient Rails DevOps, but they work equally well for any task that involves a virtual machine — the Alpine base box is especially useful for compiling statically linked Crystal projects and in environments where resources are scarce.
All boxes are intended for local development only but I try to keep them up-to-date with security patches nonetheless.
Use them however you like.
A minimal CentOS 7 installation.
A minimal CentOS 6 installation.
A minimal Alpine 3 installation.