Github Actions - Use a Dockerfile to do some work in a step

README.md

The idea is that any Docker image can be used inside the Github Action to perform a unit of work. In this example, we use an Docker image that is intended to compile our Sphinx build files. It mounts the work directory, in this case we want it on the image docs folder, launches the container and runs the make html command inside the container, which compiles the code into HTML, and places it into a folder output. The work directory is mounted to the docker container, so even ater it shuts down, we are left with the resulting files. Subsequent steps can access this directory as expected, and do whatever with it, e.g. deploy it to our server.

action.yml

jobs:
  do-build:
    runs-on: ubuntu-latest
    steps:  
    - uses: actions/checkout@v2
    - name: Build via Docker
      uses: addnab/docker-run-action@v3
      with:
        image: utmoodycollege/utdk_docs_builder:1.0-amd64
        options: -v ${{ github.workspace }}:/docs
        run: | 
            make html