How to use GitHub Actions to automatically upload to GitHub Wiki

GitHub is a great platform for hosting open source projects. It provides a lot of features for free, including a wiki for documentation. However, the wiki is primarily designed to be edited through the web interface. This is not ideal for a lot of reasons as it makes it difficult to track changes from the repository. But there is a way to automatically upload to the wiki using GitHub Actions as GitHub provides a way to checkout the wiki as a separate repository.

Create a GitHub Action to upload to the wiki

The first step is to create a GitHub Action that will upload the wiki. This can be done by creating a new file in the .github/workflows directory. The following example shows how to create a GitHub Action that will upload the wiki on every push to the master branch and on every change to the .github/workflows/wiki.yml file or the wiki directory.

Example workflow file .github/workflows/wiki.yml

---
name: GitHub Wiki upload

on:
  push:
    branches:
      - master
    paths: [wiki/**, .github/workflows/wiki.yml]

concurrency:
  group: wiki
  cancel-in-progress: true

permissions:
  contents: write

jobs:
  wiki:
    name: Publish to GitHub Wiki
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Code
        uses: actions/checkout@v4
        with:
          repository: ${{github.repository}}
          path: ${{github.repository}}

      - name: Checkout Wiki
        uses: actions/checkout@v4
        with:
          repository: ${{github.repository}}.wiki
          path: ${{github.repository}}.wiki

      - name: Push to wiki
        run: |
          set -e
          cd $GITHUB_WORKSPACE/${{github.repository}}.wiki
          cp -r $GITHUB_WORKSPACE/${{github.repository}}/wiki/* .
          git config --local user.email "[email protected]"
          git config --local user.name "GitHub Action"
          git add .
          git diff-index --quiet HEAD || git commit -m "action: wiki sync" && git push

The concurrency section is used to ensure that only one instance of the GitHub Action is running at a time. This is important as the GitHub Action will be modifying the wiki repository directly. The permissions section is used to ensure that the GitHub Action has write access to the wiki repository in the last step when the changes are pushed to the wiki repository.

Validate markdown files with pymarkdownlint

Now that the wiki is automatically updated, it is important to ensure that the markdown files are valid. This can be done using pymarkdownlint. The following example shows how to use GitHub Actions to validate markdown files in the repository.

Example workflow file .github/workflows/lint.yml

---
name: Linting

on:
  pull_request:
  push:
    branches:
      - master

jobs:
  lint:
    name: Lint Code Base
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Code
        uses: actions/checkout@v4

      - name: Set up Python
        uses: actions/setup-python@v4

      - name: Install dependencies
        run: |
          python -m pip install --upgrade pip
          python -m pip install flake8 flake8-bugbear flake8-docstrings flake8-pylint flake8-github-annotations pymarkdownlnt yamllint

      - name: Lint with yamllint
        run: |
          yamllint . --format github

      - name: Lint with flake8
        run: |
          # stop the build if there are Python syntax errors or undefined names
          flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics --format github
          # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
          flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics --format github

      - name: Lint with pymarkdownlint
        run: |
          pymarkdownlnt scan `git ls-files '*.md'`

In the final step, pymarkdownlint is used to validate all markdown files in the repository. The git ls-files '*.md' command is used to get a list of all markdown files in the repository as pymarkdownlint doesn’t scan recursivily. This is then passed to pymarkdownlint to validate the files.

Enable GitHub Annotations for pymarkdownlint

As a final step, it is useful to enable GitHub Annotations for pymarkdownlint. This will allow GitHub to display the linting errors directly in the pull request. As described in the GitHub Annotations documentation, this can be done by adding a problem matcher to the GitHub Action and then adding a problem matcher file to the repository.

Example workflow file .github/workflows/lint.yml

...
      - name: Add problem matcher
        run: |
          echo "::add-matcher::.github/annotations/pymarkdown-problem-matcher.json"

      - name: Lint with pymarkdownlint
        run: |
          pymarkdownlnt scan `git ls-files '*.md'`

The following example shows the contents of the problem matcher file for pymarkdownlint and should be saved as .github/annotations/pymarkdown-problem-matcher.json in the repository. This will allow errors to be displayed in summary of the action run.

Example problem matcher file .github/annotations/pymarkdown-problem-matcher.json

{
  "problemMatcher": [
    {
      "owner": "pymarkdown-error",
      "severity": "error",
      "pattern": [
        {
          "regexp": "^([^:]+):(\\d+):(\\d+):\\s+([^:]+:\\s+.+)$",
          "file": 1,
          "line": 2,
          "column": 3,
          "message": 4
        }
      ]
    }
  ]
}

With this workflow the GitHub Actions will automatically upload to the wiki and validate the markdown files. This will ensure that the wiki is always up to date and that the markdown files are valid. This can also be used to generate documentation from the repository and upload it to the wiki.

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