Using git sparse-checkout for faster documentation builds

Leveraging git sparse-checkout in GitHub Actions enabled us to speed up documentation builds in our repository, cutting checkout times from 20 to 30 seconds to just 2 seconds.

Developing an efficient approach to build documentation in CI workflows is essential, especially when working in large repositories with thousands of commits, like ours. Of course, we want to build documentation quickly and efficiently, ensuring fast and productive workflows. When using both the wonderful git-committers and git-revision-date-localized plugins to display document contributors and dates at the bottom of each page, we are required to set fetch-depth: 0, which resulted in checkout times of 20 to 30 seconds on our repository. By leveraging git sparse-checkout within GitHub Actions, check out time was brought down to 2 seconds.

A Primer

git sparse-checkout allows you to check out only a subset of the files in a repository, making it incredibly useful for large repositories where a full checkout takes long and includes many files that are not relevant when building documentation.

GitHub Actions

To enable git sparse-checkout within GitHub Actions and ensure that you are only building the documentation that you need, add the following lines to your workflow file:

- uses: actions/checkout@v4
  with:
    fetch-depth: 0
    sparse-checkout: |
      docs
      includes

git sparse-checkout always checks out all files residing in the repository’s root. This means that regardless of the specified paths or directories for sparse checkout, the files located in the root of the repository will always be included in the checkout process.

Thus, you only need to specify the directories that are necessary for building documentation. In our case, we only need the docs and includes folders, but if you need additional directories, you can just add them to the end of the list. A complete example workflow for GitHub Actions:

name: documentation
on:
  push:
    branches:
      - master
      - main
permissions:
  contents: write
jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
          sparse-checkout: |
            docs
            includes
      - uses: actions/setup-python@v4
        with:
          python-version: 3.x
      - run: pip install mkdocs-material
      - run: mkdocs gh-deploy --force

Conclusion

That's all there is! We're super happy with the results and hope that this will help you to speed up your documentation builds in GitHub Actions as well. As always, feel free to share your thoughts and experiences in the comments below.