Docker + Rails + Redis + Postgres

Dockerfile

# base on latest ruby base image
FROM ruby:latest

# update and install dependencies
RUN apt-get update -qq
RUN DEBIAN_FRONTEND=noninteractive apt-get install -y build-essential libpq-dev nodejs apt-utils postgresql-client

# setup app folders
RUN mkdir /sample
WORKDIR /sample

# copy over Gemfile and install bundle
ADD Gemfile /sample/Gemfile
ADD Gemfile.lock /sample/Gemfile.lock
RUN bundle install

# copy over remaining app files
ADD . /sample

# Run
EXPOSE 3000
CMD ["rails", "server"]

fig.yml

db:
  image: postgres:9.4
  ports:
    - "5432"
redis:
  image: redis:2.8.19
  ports:
    - 6379:6379
web:
  build: .
  #command: bundle exec rails server -p 3000
  command: bundle exec unicorn -p 3000 -c ./config/unicorn.rb
  volumes:
    - .:/sample
  ports:
    - 3000:3000
  links:
    - db
    - redis