Dockerfile

# syntax = docker/dockerfile:1

# Make sure RUBY_VERSION matches the Ruby version in .ruby-version and Gemfile
ARG RUBY_VERSION=3.3.6
FROM ruby:$RUBY_VERSION-slim AS base

# Rails app lives here
WORKDIR /rails

# Set production environment
ENV BUNDLE_DEPLOYMENT="1" \
  BUNDLE_PATH="/usr/local/bundle" \
  BUNDLE_WITHOUT="development:test" \
  RAILS_ENV="production" \
  SOLID_QUEUE_IN_PUMA="true"

# Update gems and bundler
RUN gem update --system --no-document && \
  gem install -N bundler


# Throw-away build stage to reduce size of final image
FROM base AS build

# Install packages needed to build gems
RUN apt-get update -qq && \
  apt-get install --no-install-recommends -y build-essential pkg-config

# Install application gems
COPY Gemfile Gemfile.lock ./
RUN bundle install && \
  bundle exec bootsnap precompile --gemfile && \
  rm -rf ~/.bundle/ "${BUNDLE_PATH}"/ruby/*/cache "${BUNDLE_PATH}"/ruby/*/bundler/gems/*/.git

# Copy application code
COPY . .

# Precompile bootsnap code for faster boot times
RUN bundle exec bootsnap precompile app/ lib/

# Precompiling assets for production without requiring secret RAILS_MASTER_KEY
RUN SECRET_KEY_BASE_DUMMY=1 ./bin/rails assets:precompile


# Final stage for app image
FROM base

# Install packages needed for deployment
RUN apt-get update -qq && \
  apt-get install --no-install-recommends -y curl libjemalloc2 libvips sqlite3 && \
  rm -rf /var/lib/apt/lists /var/cache/apt/archives

# Copy built artifacts: gems, application
COPY --from=build "${BUNDLE_PATH}" "${BUNDLE_PATH}"
COPY --from=build /rails /rails

# Run and own only the runtime files as a non-root user for security
RUN groupadd --system --gid 1000 rails && \
  useradd rails --uid 1000 --gid 1000 --create-home --shell /bin/bash && \
  mkdir /data && \
  chown -R 1000:1000 db log storage tmp /data
USER 1000:1000

# Deployment options
ENV DATABASE_URL="sqlite3:///data/production.sqlite3"

# Entrypoint prepares the database.
ENTRYPOINT ["/rails/bin/docker-entrypoint"]

# Start the server by default, this can be overwritten at runtime
EXPOSE 3000
VOLUME /data
CMD ["./bin/rails", "server"]