Mastering GitLab 12

Build step

The main idea is that, in the build phase, you prepare your code to run in a packaged way – in a Docker container that you built using a Dockerfile – via Heroku build packs.

For the eventmanager app, user1 created the following Dockerfile:

  FROM ruby:2   COPY . /var/www/ruby   WORKDIR /var/www/ruby   RUN bundle install   CMD ["ruby","eventmanager.rb"]   EXPOSE 5000/tcp

As you can see from the first line of the preceding code, it pulls a basic Ruby-enabled Debian Linux image. It copies all the source code to a directory and goes there. Then, a bundle install is run, which installs all the Ruby dependencies that are needed. Finally, it starts the eventmanager app using the CMD command and exposes port 5000 to the outside world. It has to expose ...