This post shows how to inject Google Analytics tracking (gtag.js) into an HTML file with GitHub Actions.

Problem

You want to add Google Analytics to a generated HTML file in CI without touching the source code.

Solution

Use the google-analytics-action to inject the gtag.js script in your GitHub Action workflow.

Usage

Add the action after your build step:

# .github/workflows/build.yml
name: Build
on:
  push:
    branches: [master]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v7

      - name: Build static site
        run: npm run build

      - name: Inject Google Analytics
        uses: remarkablemark/google-analytics-action@v1
        with:
          html-path: dist/index.html
          measurement-id: ${{ secrets.GOOGLE_ANALYTICS_ID }}

Inputs

• html-path (required): The HTML file to modify.
• measurement-id (required): The Google Analytics Measurement ID (e.g., G-XXXXXXXXXX).

Behavior

The action:

• Injects the gtag.js script before the closing </head> tag.
• Falls back to inserting before </body> if </head> is not present.
• Skips injection if the snippet for the same measurement ID is already present (idempotent).
• Fails if the file does not exist or if neither </head> nor </body> is found.

Example

Before:

<!doctype html>
<html>
  <head>
    <title>My Site</title>
  </head>
  <body>
    <h1>Hello, world!</h1>
  </body>
</html>

After:

<!doctype html>
<html>
  <head>
    <title>My Site</title>
    <script async src="https://www.googletagmanager.com/gtag/js?id=G-XXXXXXXXXX"></script>
    <script>
      window.dataLayer = window.dataLayer || [];
      function gtag(){dataLayer.push(arguments);}
      gtag('js', new Date());
      gtag('config', 'G-XXXXXXXXXX');
    </script>
  </head>
  <body>
    <h1>Hello, world!</h1>
  </body>
</html>

See the action source code.