title: Gitlab CI in multiple platforms simultaneously
body: <p>I have a C++ project that is compiled and packaged for multiple OS (Linux, Windows, MacOS) as well as multiple CPU architectures (i386, x86_64, arm, Aarch64)
  For this I'm using Jenkins to grab the source code and run the build script in parallel on each system. It's a simple working solution, since my build script deals with the system differences.</p>
  
  <p>Now I'm looking into Gitlab CI/CD, and it has many things I find appealing ( being able to keep the build script as part of the repository, very well integrated with the git repo and ticketing system, natural use of Docker containers, etc), but I cannot find any way to run the same pipeline in multiple architectures/systems parallel to each other.</p>
  
  <p>So, say that my build script is:</p>
  
  <pre><code>build:
    stage: build
    script: 
      - uname -m &gt; arch.txt
    artifacts:
      paths:
        - arch.txt
  </code></pre>
  
  <p>How can I tell Gitlab that I want to run this job in multiple runners/Docker containers/systems at the same time?  All the documentation I've read so far deals with <a href="https://docs.gitlab.com/ee/ci/pipelines.html#types-of-pipelines" rel="noreferrer">running multiple tests on one build</a>, <a href="https://docs.gitlab.com/ee/ci/multi_project_pipelines.html" rel="noreferrer">integrating multiple projects</a> or <a href="https://docs.gitlab.com/ee/ci/environments.html" rel="noreferrer">deploying in different environments depending on branches</a>. Nothing I've read so far tries to do many separate builds, test and package them individually and report on their independent results. Is this feasible on Gitlab CI/CD?</p>