docker-compose.prod.yml

version: '2.4'

 services:
   app: &app
     build:
       context: .
       dockerfile: ./docker/Dockerfile.prod
       args:
         RUBY_VERSION: '2.7.0'
         PG_MAJOR: '12'
         NODE_MAJOR: '12'
         YARN_VERSION: '1.13.0'
         BUNDLER_VERSION: '2.1.3'
     image: unc-prod:0.0.1
     tmpfs:
       - /tmp

   backend: &backend
     <<: *app
     stdin_open: true
     tty: true
     volumes:
       - .:/app:cached
       - rails_cache:/app/tmp/cache
       - bundle:/usr/local/bundle
       - node_modules:/app/node_modules
       - packs:/app/public/packs
       - docker/.psqlrc:/root/.psqlrc:ro
     environment:
       - NODE_ENV=development
       - RAILS_ENV=${RAILS_ENV:-development}
       - REDIS_URL=redis://redis:6379/
       - DATABASE_URL=postgres://postgres:postgres@postgres:5432
       - BOOTSNAP_CACHE_DIR=/bundle/bootsnap
       - WEBPACKER_DEV_SERVER_HOST=webpacker
       - WEB_CONCURRENCY=1
       - HISTFILE=/app/log/.bash_history
       - PSQL_HISTFILE=/app/log/.psql_history
       - EDITOR=vi
     depends_on:
       postgres:
         condition: service_healthy
       redis:
         condition: service_healthy

   runner:
     <<: *backend
     command: /bin/bash
     ports:
       - '3000:3000'
       - '3002:3002'

   rails:
     <<: *backend
     command: bundle exec rails server -b 0.0.0.0
     ports:
       - '3000:3000'

   sidekiq:
     <<: *backend
     command: bundle exec sidekiq -C config/sidekiq.yml

   postgres:
     image: postgres:12.1
     volumes:
       - .psqlrc:/root/.psqlrc:ro
       - postgres:/var/lib/postgresql/data
       - ./log:/root/log:cached
     environment:
       - PSQL_HISTFILE=/root/log/.psql_history
     ports:
       - 5432
     healthcheck:
       test: pg_isready -U postgres -h 127.0.0.1
       interval: 5s

   redis:
     image: redis:3.2-alpine
     volumes:
       - redis:/data
     ports:
       - 6379
     healthcheck:
       test: redis-cli ping
       interval: 1s
       timeout: 3s
       retries: 30

   webpacker:
     <<: *app
     command: ./bin/webpack-dev-server
     ports:
       - '3035:3035'
     volumes:
       - .:/app:cached
       - bundle:/usr/local/bundle
       - node_modules:/app/node_modules
       - packs:/app/public/packs
     environment:
       - NODE_ENV=${NODE_ENV:-development}
       - RAILS_ENV=${RAILS_ENV:-development}
       - WEBPACKER_DEV_SERVER_HOST=0.0.0.0

 volumes:
   postgres:
   redis:
   bundle:
   node_modules:
   rails_cache:
   packs:

Dockerfile.prod

ARG RUBY_VERSION
 # See explanation below
 FROM ruby:$RUBY_VERSION-slim-buster

 ARG PG_MAJOR
 ARG NODE_MAJOR
 ARG BUNDLER_VERSION
 ARG YARN_VERSION

 # Common dependencies
 RUN apt-get update -qq \
   && DEBIAN_FRONTEND=noninteractive apt-get install -yq --no-install-recommends \
     build-essential \
     gnupg2 \
     curl \
     less \
     git \
   && apt-get clean \
   && rm -rf /var/cache/apt/archives/* \
   && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* \
   && truncate -s 0 /var/log/*log

 # Add PostgreSQL to sources list
 RUN curl -sSL https://www.postgresql.org/media/keys/ACCC4CF8.asc | apt-key add - \
   && echo 'deb http://apt.postgresql.org/pub/repos/apt/ buster-pgdg main' $PG_MAJOR > /etc/apt/sources.list.d/pgdg.list

 # Add NodeJS to sources list
 RUN curl -sL https://deb.nodesource.com/setup_$NODE_MAJOR.x | bash -

 # Add Yarn to the sources list
 RUN curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - \
   && echo 'deb http://dl.yarnpkg.com/debian/ stable main' > /etc/apt/sources.list.d/yarn.list

 # Application dependencies
 # We use an external Aptfile for that, stay tuned
 COPY .docker/Aptfile /tmp/Aptfile
 RUN apt-get update -qq && DEBIAN_FRONTEND=noninteractive apt-get -yq dist-upgrade && \
   DEBIAN_FRONTEND=noninteractive apt-get install -yq --no-install-recommends \
     libpq-dev \
     postgresql-client-$PG_MAJOR \
     nodejs \
     yarn=$YARN_VERSION-1 \
     $(cat /tmp/Aptfile | xargs) && \
     apt-get clean && \
     rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* && \
     truncate -s 0 /var/log/*log

 # Configure bundler
 ENV LANG=C.UTF-8 \
   BUNDLE_JOBS=4 \
   BUNDLE_RETRY=3

 # Uncomment this line if you store Bundler settings in the project's root
 # ENV BUNDLE_APP_CONFIG=.bundle

 # Uncomment this line if you want to run binstubs without prefixing with `bin/` or `bundle exec`
 # ENV PATH /app/bin:$PATH

 # Upgrade RubyGems and install required Bundler version
 RUN gem update --system && \
     gem install bundler:$BUNDLER_VERSION

 # Create a directory for the app code
 RUN mkdir -p /app
 ADD . /app
 WORKDIR /app

 CMD ["/usr/bin/entrypoint.sh"]