Using Docker for RubyGems projects

Sometimes I want to create a new gem or modify existing gems to extend/fix them. However, I do not want to install tons of additional development tools on my host machine for that. Recently, I created a shell script which creates an instant development environment on Docker for that.

#!/bin/sh -e
exec docker run --rm -it \
  --workdir=/work \
  -v $(pwd):/work \
  -v=$HOME/.gitconfig:/root/.gitconfig \
  -v=$HOME/.ssh:/root/.ssh \
  -v=$HOME/.gem/credentials:/root/.gem/credentials \
  ruby:${VERSION:-2.6.5} \
  /bin/bash "$@"

This is a deadly-simple wrapper for docker command to run a ruby container mounting minimum-required files. Just put this file under a directory whatever it is in $PATH list (For example, /usr/local/bin/rubyshell) and run rubyshell in a Ruby project. Then I can do Ruby things such as bundle.

It is such a cheap environment but handy enough because I just want to run only a few ruby/bundler commands so far.