A docker image that includes all dependencies to build ruby.
The cron jobs of Travis CI will rebuild and push a new image periodically (per month). This is used by rubyfarmer.
$ docker pull rubylang/ruby-build-env
$ docker run --rm -ti rubylang/ruby-build-env
# git clone https://github.com/ruby/ruby.git
# cd ruby
# autoconf
# ./configure --prefix=/somewhere
# make
# make install