Docker is a bit orthogonal, IMO. One key problem these tools solve is getting a specified version of ruby onto a host at a granularity other that "whatever's i

Docker is a bit orthogonal, IMO. One key problem these tools solve is getting a specified version of ruby onto a host at a granularity other that "whatever's in my distro's package repo". It's certainly possible to simplify matters and just use ruby-build[1] to normalize ruby acquisition. AFAICT, this is out of scope for Dockerfiles in recent incarnations. [1] https://github.com/sstephenson/ruby-build https://github.com/sstephenson/ruby-build