This Dockerfile builds a lightweight linux image based on Alpine Linux (5MB to start) with all the tools needed to build a Ruby project (i.e. compile/install gems).
It includes postgres support as a library (i.e. not the Postgres server, but just library code to compile against)
It is currently customized to projects I am working on, so it may not have all the necessary libraries.
NOTE: This is for building. For running a Ruby project in a docker image use: ifpironimages/ruby-run
RUN apk update && apk upgrade
RUN apk add build-base curl-dev bash libffi-dev libxml2-dev libxslt-dev readline-dev postgresql-dev
RUN apk add ruby ruby-dev ruby-io-console ruby-bundler ruby-irb
RUN gem install --no-ri --no-rdoc bundler
RUN bundle config build.nokogiri --use-system-libraries
RUN rm -rf /var/cache/apk/*