Github Action for PR previews

Create a file path named .github/workflows/preview.yml at the root of your project.

Inside preview.yml, copy and paste the following snippet:

name: preview
on: pull_request

jobs:
  update:
    name: EAS Update
    runs-on: ubuntu-latest
    permissions:
      contents: read
      pull-requests: write
    steps:
      - name: Check for EXPO_TOKEN
        run: |
          if [ -z "${{ secrets.EXPO_TOKEN }}" ]; then
            echo "You must provide an EXPO_TOKEN secret linked to this project's Expo account in this repo's secrets. Learn more: https://docs.expo.dev/eas-update/github-actions"
            exit 1
          fi

      - name: Checkout repository
        uses: actions/checkout@v4

      - name: Setup Node
        uses: actions/setup-node@v4
        with:
          node-version: 18.x
          cache: yarn

      - name: Setup EAS
        uses: expo/expo-github-action@v8
        with:
          eas-version: latest
          token: ${{ secrets.EXPO_TOKEN }}

      - name: Install dependencies
        run: yarn install

      - name: Create preview
        uses: expo/expo-github-action/preview@v8
        with:
          command: eas update --auto

In the above script:

• You are using the workflow event on to run every time a pull request is opened or updated.
• In the update job, the Node.js version, Expo's GitHub Action and the dependencies are set up using GitHub Action's built-in cache.
• The eas update --auto is run by the preview subaction. It adds a comment to the pull request with basic information about the update and a QR code to scan the update.

Don't forget to add the permissions section to the job. This enables the job to add comments to the pull request.

You can skip this step if you have already set up EXPO_TOKEN in the previous section. Only one valid EXPO_TOKEN is required to authenticate GitHub Actions with your Expo account.

If you haven't, you need to give the script above permission to run by providing an EXPO_TOKEN environment variable.

• Navigate to https://expo.dev/settings/access-tokens.
• Click Create token to create a new personal access token.
• Copy the token generated.
• Navigate to https://github.com/your-username/your-repo-name/settings/secrets/actions by replacing "your-username" and "your-repo-name" with your project's info.
• Under Repository secrets, click New repository secret.
• Create a secret with the name EXPO_TOKEN, and paste the copied access token in as the value.

Replace the Setup Node step in update.yml or preview.yml with the following snippet:

- name: Setup Bun
  uses: oven-sh/setup-bun@v1
  with:
    bun-version: latest

To install dependencies using Bun, replace the Install dependencies step with the following snippet:

- name: Install dependencies
  run: bun install