Utilizing Docker's data-only container

docker-compose.yml

# Main application
web:
  container_name: rails_web
  build: .
  command: bash ./start.sh
  volumes:
    - .:/app
  ports:
    - "80:3000"
  volumes_from:
    - bundle_store

# Data-only container for bundler data
# create the volume by doing: docker volume create bundle_store
bundle_store:
  container_name: rails_bundle_store
  image: cogniteev/echo
  command: echo 'Data Container for Bundler'
  volumes:
    - bundle_store:/usr/local/bundle

Dockerfile

# Choose the official Ruby 2.3.0 image as our starting point
FROM ruby:2.3.0

# Run updates for nokogiri and JS runtime
RUN apt-get update -qq && apt-get install -y build-essential libxml2-dev libxslt1-dev nodejs

# Cleanup
RUN apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

# Set up working directory
RUN mkdir /app
WORKDIR /app

# Set up bundle environment
ENV BUNDLE_JOBS=3 BUNDLE_GEMFILE=/app/Gemfile

start.sh

#!/bin/bash

bundle check || bundle install

rm -f /app/tmp/pids/server.pid

rails s -b 0.0.0.0