Some snippets for GitHub Actions

Some snippets of GitHub actions YAML code that you can copy-and-paste, old school style.

Why this? Isn’t the selling point of GitHub Actions the fact that you can share and reuse others’ actions?? Yes, but sometimes there are cases where I prefer to just copy-and-paste YAML code instead of reusing others’ actions:

• Sometimes I want to customize the action’s code without going through the repository forking dance.

• There are security concerns regards using others’ actions. Sure, we can trust official actions and actions created by big companies, but random strangers on the internet? Hmmm. Even if we strictly use commit hash instead of tag, our actions YAML will be full of Git hashes instead of meaningful versions, and so we lose out on automatic updates. I’m also not sure what’s going to happen if the actions’ repository is deleted or if the owner’s account is suspended or deleted.

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By the way, the contents you will see below is automatically generated from GitHub Issues.

• They are sorted by score, where 👍 😄 🎉 ❤️ reactions count as upvote and 👎 😕 reactions count as downvote. So if you find any snippet helpful, please give a reaction on the corresponding issue!

• Of course, this is implemented using GitHub Actions!

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Table of contents

• Commit and push local changes back to GitHub
• Making emojis render properly in headless browsers
• Post to a Slack channel
• Run a job only when commit message matches a certain keyword
• Run inline Node.js script

Commit and push local changes back to GitHub

GitHub Actions can push commits back into the respository. Use cases include:

• Automatically generating README file from GitHub Issues
• Creating a self-updating repository
• Keeping app screenshots up-to-date

      - name: Push changes back to GitHub
        env:
          GIT_COMMITTER_NAME: Janitor
          GIT_AUTHOR_NAME: Janitor
          EMAIL: repository-janitor[bot]@users.noreply.github.com
        run: |
          git add --all \
            && git commit -m "Update $(node -p 'new Date().toJSON()')" \
            || echo "Nothing to commit"
          git push "https://x-access-token:${{ secrets.GITHUB_TOKEN }}@github.com/$GITHUB_REPOSITORY.git" "$GITHUB_REF"

^{submitted by @dtinth (#1)}

Making emojis render properly in headless browsers

Useful for workflows that uses a headless browser to render pages that may contain emojis.

      - name: Install Noto fonts and add emoji support
        run: sudo apt-get install fonts-noto fonts-noto-color-emoji -y

^{submitted by @dtinth (#2)}

Post to a Slack channel

Useful for building alerts on (e.g.) build or test failures, as well as other miscellaneous use cases.

      - name: Generate a Slack message
        run: |
          echo '{"text":"Hello world"}' | tee /tmp/slack.json
      - name: Post to Slack
        run: |
          test -f /tmp/slack.json && curl -X POST -H 'Content-type: application/json' -d @/tmp/slack.json "${{ secrets.SLACK_WEBHOOK_URL }}"

^{submitted by @dtinth (#3)}

Run a job only when commit message matches a certain keyword

Useful when you want to save costs… especially macOS builds, which can be expensive. Sometimes building on every single commit may not be the best idea…

jobs:
  build:
    if: "contains(github.event.head_commit.message, '[build]')"

^{submitted by @dtinth (#5)}

Run inline Node.js script

Sometimes you need to run a Node.js script and it’s so simple you might as well inline it into your workflow file…

      - run: |
          node << 'EOF'
            console.log('Hello!')
          EOF

^{submitted by @dtinth (#4)}