Dockerfile

# Set the alpine version so they match for both images
ARG ALPINE_VERSION=3.21

# Set the Ruby version
ARG RUBY_VERSION=3.4.7

# Pull in the Ruby image
FROM ruby:${RUBY_VERSION}-alpine${ALPINE_VERSION} AS base

# Rails app lives here
WORKDIR /rails

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

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

# Install application dependencies
RUN apk add --update --no-cache \
    build-base \
    curl \
    git \
    libpq-dev \
    yaml-dev \
    tzdata \
    bash

# Install JavaScript dependencies
ENV BUN_INSTALL=/usr/local/bun
ENV PATH=/usr/local/bun/bin:$PATH
ARG BUN_VERSION=1.2.13
RUN curl -fsSL https://bun.sh/install | bash -s -- "bun-v${BUN_VERSION}"

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

# Install node modules
COPY package.json bun.lock ./
RUN bun install --frozen-lockfile

# 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 apk add --update --no-cache \	
    bash \	
    ca-certificates \	
    curl \	
    libpq-dev \	
    tzdata	

# 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 adduser rails -D --shell /bin/bash

# Own the runtime files for the app
RUN chown -R rails:rails db log tmp data

USER rails:rails

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

# Run the web app on port 3000
EXPOSE 3000

# Start the server by default, this can be overwritten at runtime
CMD ["./bin/rails", "server", "-b", "0.0.0.0"]