Rails in Docker

commands

docker-compose build
docker-compose up
docker-compose run app rake db:create
docker-compose run app rake db:migrate

database.yml

default: &default
  adapter: postgresql
  pool: 5
  timeout: 5000
  username: postgres
  host: db
  port: 5432

development:
  <<: *default
  database: app_development

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  <<: *default
  database: app_test

production:
  <<: *default
  database: app

docker-compose.yml

app:
  build: .
  command: rails server -p 3000 -b '0.0.0.0'
  volumes:
    - .:/app
  ports:
    - "3000:3000"
  links:
    - db
db:
  image: postgres:9.5
  ports:
    - "5432"

Dockerfile

FROM ruby:2.3
MAINTAINER [email protected]

# Install apt based dependencies required to run Rails as
# well as RubyGems. As the Ruby image itself is based on a
# Debian image, we use apt-get to install those.
RUN   apt-get update && \
      apt-get install -y \
      build-essential \
      nodejs

# Configure the main working directory. This is the base
# directory used in any further RUN, COPY, and ENTRYPOINT
# commands.
RUN mkdir -p /app
WORKDIR /app

# Copy the Gemfile as well as the Gemfile.lock and install
# the RubyGems. This is a separate step so the dependencies
# will be cached unless changes to one of those two files
# are made.
COPY Gemfile Gemfile.lock ./
RUN gem install bundler && bundle install --jobs 20 --retry 5

# Copy the main application.
COPY . ./

# Expose port 3000 to the Docker host, so we can access it
# from the outside.
EXPOSE 3000

# Configure an entry point, so we don't need to specify
# "bundle exec" for each of our commands.
ENTRYPOINT ["bundle", "exec"]

# The main command to run when the container starts. Also
# tell the Rails dev server to bind to all interfaces by
# default.
CMD ["rails", "server", "-b", "0.0.0.0"]