GitHub Push Action

Today we’re looking at ad-m/github-push-action, the third and final action related to pushing changes made during a GitHub Actions workflow run back to a repo.

What does it do?

Unlike git-auto-commit-action and add-and-push, github-push-action doesn’t handle committing files for you. It expects your workflow to add and commit any files you need and handles the act of pushing changes to GitHub.

You might be thinking that this seems like an odd action to build; surely it’s as simple as running git push and it works? Unfortunately not! The repository provided in your workspace doesn’t have permission to push changes back so you need to configure your repo to use the GITHUB_TOKEN provided in order to have write permission.

How does it work?

This action is an interesting one as it uses both javascript and bash components to get the job done. start.js is the main entry point, which allows the action to run start.sh on Linux, MacOS and Windows runners.

Let’s take a look at start.js first as it’s the main entry point:

• The action accepts both branch and repository as inputs.
• If repository isn’t provided it defaults to GITHUB_REPOSITORY in the environment. If it is provided, that will be used as the destination repository, allowing your workflow to push to other repositories.
• If branch is provided it is used as-is. If it is not provided the script uses the GitHub API to fetch the default branch for the repo and uses that as the input value
• Finally, it executes start.sh ensuring that both INPUT_BRANCH and INPUT_REPOSITORY have values

What’s interesting to note here is that start.js does not have any dependencies. It uses the http module for making HTTP requests and the child_process module to executestart.sh. actions/exec is typically used for this use case, but github-push-action does not use any dependencies so that there is no build step required for the JS action.

Now, on to start.sh:

We see some new inputs that have defaults set in the script

• INPUT_FORCE (default false) which will run git push --force
• INPUT_TAGS (default false) which will run git push --tags
• INPUT_DIRECTORY (default ., the current directory) which controls which directory the push is run from
• REPOSITORY, which is set to INPUT_REPOSITORY or GITHUB_REPOSITORY. This is a duplication of the logic in start.js
  • The GITHUB_TOKEN secret is required to push to the repo, so we check that it’s been set as INPUT_GITHUB_TOKEN
  • If INPUT_FORCE is true then add --force to the push options
  • If INPUT_TAGS is set then add --tags to the push options
  • Configure the remote URL using the user:password@github.com format
  • Push the current HEAD commit to INPUT_BRANCH

Common use cases

As with the last post, this action is most useful for committing back changed files such as style fixes or build artefacts.

Run eslint and commit back:

name: Lint source code
on: push

jobs:
  run:
    name: Lint with ESLint
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repo
        uses: actions/checkout@v2

      - name: Set up Node.js
        uses: actions/setup-node@v1
        with:
          node-version: 12.x

      - name: Install dependencies
        run: npm install

      - name: Update source code
        run: eslint "src/**" --fix

      - name: Commit files
        run: |
          git config --local user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git config --local user.name "github-actions[bot]"
          git add src
          git commit -m "ESLint fixes"

      - name: Push changes
        uses: ad-m/github-push-action@master
        with:
          github_token: ${{ secrets.GITHUB_TOKEN }}
          branch: ${{ github.ref }}

Or build your project and commit back the files:

name: Automatic Compile
on: push

jobs:
  run:
    name: Compile
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repo
        uses: actions/checkout@v2

      - name: Set up Node.js
        uses: actions/setup-node@v1
        with:
          node-version: 12.x

      - name: Install dependencies
        run: npm install

      - name: Compile
        run: npm run build

      - name: Commit files
        run: |
          git config --local user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git config --local user.name "github-actions[bot]"
          git add lib
          git commit -m "Built files"

      - name: Push changes
        uses: ad-m/github-push-action@master
        with:
          github_token: ${{ secrets.GITHUB_TOKEN }}
          branch: ${{ github.ref }}

Useful links

• GitHub Marketplace
• GitHub Repo