Dockerfile

# syntax = docker/dockerfile:1
ARG RUBY_VERSION=4.0.1
FROM ruby:$RUBY_VERSION-slim AS base

WORKDIR /rails

# Set production environment
ENV RAILS_ENV="production" \
    BUNDLE_WITHOUT="development:test" \
    BUNDLE_DEPLOYMENT="1"

RUN gem update --system --no-document && \
    gem install -N bundler

# Build stage
FROM base AS build

RUN apt-get update -qq && \
    apt-get install --no-install-recommends -y \
    build-essential pkg-config libyaml-dev libsqlite3-dev && \
    rm -rf /var/lib/apt/lists /var/cache/apt/archives

# Copy gem specs
COPY --link Gemfile Gemfile.lock ./

# Install gems including executables (puma)
ENV BUNDLE_PATH="/usr/local/bundle" \
    PATH="/usr/local/bundle/bin:$PATH" \
    BUNDLE_JOBS=4 \
    BUNDLE_RETRY=3

RUN bundle install && \
    rm -rf ~/.bundle/ $BUNDLE_PATH/ruby/*/cache $BUNDLE_PATH/ruby/*/bundler/gems/*/.git

# Copy app code
COPY --link . .

# Make bin/* executable
RUN chmod +x bin/*

# Precompile assets (dummy secret to allow skipping credentials)
RUN SECRET_KEY_BASE_DUMMY=1 ./bin/rails assets:precompile

# Runtime stage
FROM base AS runtime

RUN apt-get update -qq && \
    apt-get install --no-install-recommends -y \
    libsqlite3-0 && \
    rm -rf /var/lib/apt/lists /var/cache/apt/archives

ENV BUNDLE_PATH="/usr/local/bundle" \
    PATH="/usr/local/bundle/bin:$PATH"

COPY --from=build /usr/local/bundle /usr/local/bundle
COPY --from=build /rails /rails

# Set up non-root user and permissions
RUN useradd rails --create-home --shell /bin/bash && \
    mkdir -p /data /rails/db /rails/tmp /rails/log /rails/public && \
    chown -R rails:rails /rails/db /rails/tmp /rails/log /rails/public /data
USER rails:rails

# Runtime ENV
ENV DATABASE_URL="sqlite3:///data/production.sqlite3" \
    RUBY_YJIT_ENABLE="1"

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

VOLUME /data
EXPOSE 80

# Start Puma with config file
CMD ["bundle", "exec", "puma", "-C", "config/puma.rb"]