How to Node on Ruby 2.5.0 (Debian Stretch) Docker Container

Another Ruby version, another curveball. Node is no longer in the default package repository for Debian, so you have to manually add it. Here's how I got my Dockerfile to run:

# Dockerfile
FROM ruby:2.5.0
RUN apt-get update
RUN curl -sL | bash -
RUN apt-get install -y nodejs
RUN apt-get install -y npm
RUN npm install yarn -g

CMD mkdir /app
COPY Gemfile /app
COPY Gemfile.lock /app

RUN gem install bundler -v 1.16.1
RUN bundle install