Ruby on Rails on Docker

.dockerignore

.bundle
tmp
vendor/bundle

docker-compose.yml

version: '2'
services:
  app:
    build: .
    expose:
      - "3000"
    ports:
     - "3000:3000"
    environment:
        - RAILS_ENV=development
    volumes:
     - .:/opt/app
    links:
     - db
  db:
    command: mysqld --character-set-server=utf8 --collation-server=utf8_unicode_ci
    image: "mariadb:10.1.2"
    expose:
      - "3306"
    environment:
        - MYSQL_ROOT_PASSWORD=password

Dockerfile

FROM ruby:2.3

## Optional
# RUN apt-get update
# RUN apt-get install -y nodejs npm

ADD . /opt/app
WORKDIR /opt/app

RUN mkdir /home/app

RUN bundle install

RUN useradd app
RUN chown app /home/app
USER app

EXPOSE 3000

ENTRYPOINT bundle exec rake db:create db:migrate db:seed
CMD rm /opt/app/tmp/pids/server.pid; bin/rails s -b 0.0.0.0