Containerize a Ruby on Rails application

# syntax=docker/dockerfile:1
# check=error=true

# This Dockerfile is designed for production, not development.
# docker build -t app .
# docker run -d -p 80:80 -e RAILS_MASTER_KEY=<value from config/master.key> --name app app

# For a containerized dev environment, see Dev Containers: https://guides.rubyonrails.org/getting_started_with_devcontainer.html

# Make sure RUBY_VERSION matches the Ruby version in .ruby-version
ARG RUBY_VERSION=3.3.6
FROM docker.io/library/ruby:$RUBY_VERSION-slim AS base

# Rails app lives here
WORKDIR /rails

# Install base packages
# Replace libpq-dev with sqlite3 if using SQLite, or libmysqlclient-dev if using MySQL
RUN apt-get update -qq && \
    apt-get install --no-install-recommends -y curl libjemalloc2 libvips libpq-dev && \
    rm -rf /var/lib/apt/lists /var/cache/apt/archives

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

# Install JavaScript dependencies and Node.js for asset compilation
#
# Uncomment the following lines if you are using NodeJS need to compile assets
#
# ARG NODE_VERSION=18.12.0
# ARG YARN_VERSION=1.22.19
# 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 && \
#     npm install -g mjml && \
#     rm -rf /tmp/node-build-master

# 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
#
# Uncomment the following lines if you are using NodeJS need to compile assets
#
# COPY package.json yarn.lock ./
# RUN --mount=type=cache,id=yarn,target=/rails/.cache/yarn YARN_CACHE_FOLDER=/rails/.cache/yarn \
#     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

# 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 && \
    chown -R rails:rails db log storage tmp
USER 1000:1000

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

# Start server via Thruster by default, this can be overwritten at runtime
EXPOSE 80
CMD ["./bin/thrust", "./bin/rails", "server"]

# Start the application server
EXPOSE 3000
CMD ["./bin/rails", "server"]

#!/bin/bash -e

# Enable jemalloc for reduced memory usage and latency.
if [ -z "${LD_PRELOAD+x}" ]; then
    LD_PRELOAD=$(find /usr/lib -name libjemalloc.so.2 -print -quit)
    export LD_PRELOAD
fi

# If running the rails server then create or migrate existing database
if [ "${@: -2:1}" == "./bin/rails" ] && [ "${@: -1:1}" == "server" ]; then
  ./bin/rails db:prepare
fi

exec "${@}"

services:
  web:
    build: .
    environment:
      - RAILS_MASTER_KEY
    ports:
      - "3000:80"

$ RAILS_MASTER_KEY=<master_key_value> docker compose up --build

$ docker compose up --build -d

$ docker compose down