Docker + fig with mounted volume for dev environment (and correctly handles bundle install).

command

# Running these will now correctly update the Gemfile.lock in the mounted host folder:

$ fig run web bundle install
$ fig run web bundle update <gemname>

Dockerfile

# Base image.
FROM fotinakis/baseimage-ruby:2.1.3

# System dependencies for gems.
RUN apt-get update
RUN apt-get install -y --no-install-recommends libmysqlclient-dev

# Add 'web' user which will run the application.
RUN adduser web --home /home/web --shell /bin/bash --disabled-password --gecos ""

# Add directory where all application code will live and own it by the web user.
RUN mkdir /app
RUN chown -R web:web /app

# Install gems separately here to take advantage of container caching of `bundle install`.
# Also, ensure that gems are installed as the web user and not system-wide so that we can run
# `fig web bundle install` and the web user will have permissions to update the shared Gemfile.lock.
ADD Gemfile /app/
ADD Gemfile.lock /app/
RUN chown -R web:web /app
USER web
ENV HOME /home/web
ENV PATH $PATH:/home/web/.gem/ruby/2.1.0/bin
ENV GEM_HOME /home/web/.gem/ruby/2.1.0
ENV GEM_PATH $GEM_HOME
RUN gem install --user-install bundler
WORKDIR /app/
RUN bundle install
USER root

# Add the whole application source to the image and own it all by web:web.
# Note: this is overwritten in development because fig mounts a shared volume at /app.
ADD . /app/
RUN chown -R web:web /app

# Clean up APT and /tmp when done.
RUN apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

# Default command to run when this container is run.
USER web
WORKDIR /app/
CMD ["bundle", "exec", "rails", "server"]

fig.yml

db:
  image: mysql
  environment:
    MYSQL_ROOT_PASSWORD: fizzbuzz
  ports:
    - 3306
web:
  build: .
  volumes:
    - .:/app
  ports:
    - 3000:3000
  links:
    - db

Related fig issue: docker/compose#222 (comment)