Dockerfile

# syntax = docker/dockerfile:1

# Make sure RUBY_VERSION matches the Ruby version in .ruby-version and Gemfile
ARG RUBY_VERSION=3.3.0
FROM ruby:$RUBY_VERSION-alpine3.18 as base

# Rails app lives here
WORKDIR /rails

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

# 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 --mount=type=cache,id=dev-apk-cache,sharing=locked,target=/var/cache/apk \
    apk update && \
    apk add build-base git pkgconfig vips-dev

# Install application gems
COPY --link Gemfile Gemfile.lock ./
RUN --mount=type=cache,id=bld-gem-cache,sharing=locked,target=/srv/vendor \
    bundle config set app_config .bundle && \
    bundle config set path /srv/vendor && \
    bundle install && \
    bundle exec bootsnap precompile --gemfile && \
    bundle clean && \
    mkdir -p vendor && \
    bundle config set path vendor && \
    cp -ar /srv/vendor .

# Copy application code
COPY --link . .

# 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 --mount=type=cache,id=dev-apk-cache,sharing=locked,target=/var/cache/apk \
    apk update && \
    apk add curl imagemagick jemalloc sqlite-dev sqlite-libs vips-dev

# 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 addgroup --system --gid 1000 rails && \
    adduser --system rails --uid 1000 --ingroup rails --home /home/rails --shell /bin/sh rails && \
    mkdir /data && \
    chown -R 1000:1000 db log storage tmp /data

# Deployment options
ENV DATABASE_URL="sqlite3:///data/production.sqlite3" \
    LD_PRELOAD="libjemalloc.so.2" \
    MALLOC_CONF="dirty_decay_ms:1000,narenas:2,background_thread:true" \
    RUBY_YJIT_ENABLE="1"

# 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"]