Rbenv → specifies a Ruby version
Ruby → loads some gems that are part of the base Ruby distribution (bundler, rubygems, irb, etc)
Rubygems →loads other gems (for the system or user) →
Bundler → loads other gems (for the current project) →
So basically Ruby ships with a bunch of gems, rubygems manages most of the gems you install, and bundler manages all of the gems for a specific project, and both rubygems and bundler ship with Ruby.
The initial release of Docker was done at PyCon in 2013, but I wonder how much Ruby and the various shades of gem catostrophe helped inspire Docker adoption?
If you're using Docker and thus only running a single set of
gems at a time, I think you should simplify the models as much as possible. For a ruby focused docker container, just skip
rbenv and similar tools, try to bypass the system gems as much as possible, and try to get bundler / rubygems to force everything into /gems.
You'll want to check what bundler and rubygems detect as the environment via:
bundler env gems env
Basically, inside of your
Dockerfile and perhaps even your
dip.yml you want to set
HOME: /app BUNDLE_PATH: /gems GEM_HOME: /gems GEM_PATH: /gems PATH: /gems/ruby/<ruby-version>/bin:/gems/bin:/app/bin:$PATH
Also, I found my local
docker build environment to be far less annoying when I figured out how to run everything as my local user... Ultimately I need to move to actually using a text template system to process all of the required variables (it's pretty lame that the Docker people make permissions that match the developer impossible without your own wrappers) but if it bothers you enough you could always fork docker.
ARG UID=<your id -u> ARG GID=<your id -g> ARG APPUSER=appuser RUN set -x \ && addgroup --system --gid $GID $APPUSER || true \ && adduser --system --disabled-login --ingroup $APPUSER --no-create-home --home /app --gecos "$APPUSER" --shell /bin/false --uid $UID $APPUSER || true USER $APPUSER # Why on earth does Docker's COPY always copy as root instead of the USER: you set? Only the Docker people know... COPY --chown=$APPUSER: Gemfile* /app/
Then in your
dip.yml makle sure to add
run_options for your user...
interaction: shell: description: Open the Bash Shell in Container service: web command: bash compose: run_options: ["no-deps", "user=<your id -u>"]