Personal Rails Docker Setup

.dockerignore

# See https://help.github.com/articles/ignoring-files for more about ignoring files.
#
# If you find yourself ignoring temporary files generated by your text editor
# or operating system, you probably want to add a global ignore instead:
#   git config --global core.excludesfile '~/.gitignore_global'

# Ignore bundler config.
/.bundle

# Ignore the default SQLite database.
/db/*.sqlite3
/db/*.sqlite3-journal
/db/*.sqlite3-*

# Ignore all logfiles and tempfiles.
/log/*
/tmp/*
!/log/.keep
!/tmp/.keep

# Ignore pidfiles, but keep the directory.
/tmp/pids/*
!/tmp/pids/
!/tmp/pids/.keep

# Ignore uploaded files in development.
/storage/*
!/storage/.keep

/public/assets
.byebug_history

# Ignore master key for decrypting credentials and more.
/config/master.key
vendor/bundle

/public/packs
/public/packs-test
/node_modules
/yarn-error.log
yarn-debug.log*
.yarn-integrity

aliases.sh

# Aliases for running commands within the app.

alias rails="docker-compose run --rm web bundle exec rails"
alias bundle="docker-compose run --rm web bundle"
alias rake="docker-compose run --rm web bundle exec rake"
alias start="docker-compose up --build --force-recreate"

docker-compose.yml

version: '3.8'
services:
  postgres:
    image: postgres:9
    environment:
      POSTGRES_USER: 'root'
      POSTGRES_PASSWORD: 'abc123'
    volumes:
      - pg-data:/var/lib/postgresql/data
  redis:
    image: redis
  web:
    build:
      context: ./
      target: rails-builder
    stdin_open: true
    tty: true
    ports:
      - "${PORT:-3000}:5000"
    volumes:
      - ./:/app/
    depends_on:
      - postgres
      - redis
    links:
      - postgres
      - redis
    environment:
      DATABASE_URL: postgres://postgres:postgres@postgres:5432/
      DATABASE_CLEANER_ALLOW_REMOTE_DATABASE_URL: "true"
      REDIS_URL: redis://redis:6379
    restart: always
volumes:
  pg-data:

Dockerfile

#### Base rails image, used for `rails new` and other commands.
FROM ruby:2.7-alpine AS rails

RUN apk add --update --no-cache --quiet \
    build-base \
    nodejs-current \
    postgresql-dev \
    sqlite-dev \
    tzdata \
    yarn

RUN echo -e "source 'https://rubygems.org'\ngem 'rails'" > /Gemfile
RUN bundle install --quiet

FROM rails as rails-builder

RUN apk add --update --no-cache --quiet \
    build-base \
    nodejs-current \
    postgresql-dev \
    sqlite-dev \
    tzdata \
    yarn

WORKDIR /app/

COPY Gemfile Gemfile.lock /app/
RUN bundle config --global frozen 1 \
    && bundle install --quiet -j4 --retry 3 \
    # Remove unneeded files (cached *.gem, *.o, *.c)
    && rm -rf /usr/local/bundle/cache/*.gem \
    && find /usr/local/bundle/gems/ -name "*.c" -delete \
    && find /usr/local/bundle/gems/ -name "*.o" -delete

EXPOSE 5000
CMD bundle exec rails server -b 0.0.0.0 -p 5000

#### Builder is used to build assets and delete side effects.
FROM rails-builder AS builder

COPY Gemfile Gemfile.lock /app/
RUN rm -rf /usr/local/bundle \
    && bundle config --global frozen 1 \
    && bundle config set without 'development test' \
    && bundle install --quiet -j4 --retry 3 \
    # Remove unneeded files (cached *.gem, *.o, *.c)
    && rm -rf /usr/local/bundle/cache/*.gem \
    && find /usr/local/bundle/gems/ -name "*.c" -delete \
    && find /usr/local/bundle/gems/ -name "*.o" -delete

COPY package.json yarn.lock /app/
RUN yarn install

COPY ./ /app/
RUN RAILS_ENV=production SECRET_KEY_BASE=not_for_prod bundle exec rake assets:precompile
RUN rm -rf node_modules tmp/cache app/assets vendor/assets lib/assets spec

# Final image
FROM ruby:2.7-alpine AS final

# Set Rails env
ENV RAILS_LOG_TO_STDOUT true
ENV RAILS_SERVE_STATIC_FILES true
ENV EXECJS_RUNTIME Disabled

RUN apk add --update --no-cache postgresql-client

# Add user
RUN addgroup -g 1000 -S app \
 && adduser -u 1000 -S app -G app
USER app

WORKDIR /app

# Copy app with gems from former build stage
COPY --from=builder /usr/local/bundle/ /usr/local/bundle/
COPY --from=builder --chown=app:app /app /app