Dockerfile

# syntax = docker/dockerfile:1

# Make sure RUBY_VERSION matches the Ruby version in .ruby-version and Gemfile
ARG RUBY_VERSION=3.3.1
FROM registry.docker.com/library/ruby:$RUBY_VERSION-slim as base

# Rails app lives here
WORKDIR /exampleapp

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


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

# Install packages needed to build gems and node modules
RUN apt-get update -qq && \
    apt-get install --no-install-recommends -y build-essential curl git libvips libpq-dev \
                                               node-gyp pkg-config python-is-python3

# Install JavaScript dependencies
ARG NODE_VERSION=20.11.1
ARG YARN_VERSION=1.22.22
ENV PATH=/usr/local/node/bin:$PATH
RUN curl -sL https://github.com/nodenv/node-build/archive/master.tar.gz | tar xz -C /tmp/ && \
    /tmp/node-build-master/bin/node-build "${NODE_VERSION}" /usr/local/node && \
    npm install -g yarn@$YARN_VERSION && \
    rm -rf /tmp/node-build-master

# Install application gems
COPY Gemfile Gemfile.lock ./
RUN --mount=type=secret,id=bundle_config,dst=/root/.bundle/config,uid=1000 \
    bundle install && \
    rm -rf "${BUNDLE_PATH}"/ruby/*/cache "${BUNDLE_PATH}"/ruby/*/bundler/gems/*/.git && \
    bundle exec bootsnap precompile --gemfile

# Install node modules
COPY package.json yarn.lock ./
RUN yarn 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 apt-get update -qq && \
    apt-get install --no-install-recommends -y curl libvips postgresql-client netcat-openbsd && \
    rm -rf /var/lib/apt/lists /var/cache/apt/archives

# Copy built artifacts: gems, application
COPY --from=build /usr/local/bundle /usr/local/bundle
COPY --from=build /exampleapp /exampleapp

# Add the version and branch to the root of the repository
ARG VERSION
ARG BRANCH
RUN if [ "$VERSION" != "" ]; then echo $VERSION > /exampleapp/VERSION; fi \
  && if [ "$BRANCH" != "" ]; then echo $BRANCH > /exampleapp/BRANCH; fi

# Run and own only the runtime files as a non-root user for security
RUN useradd exampleapp --create-home --shell /bin/bash && \
    chown -R exampleapp:exampleapp log tmp
USER exampleapp:exampleapp

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

# Start the server by default, this can be overwritten at runtime
EXPOSE 3000
CMD ["./bin/puma", "-C", "config/puma.rb"]