submodules_update.yml

name: Update Submodules
on:
  # schedule:
  # run daily at midnight
  # - cron: '0 0 * * *'
  # Allows you to run this workflow manually from the Actions tab
  workflow_dispatch:

jobs:
  update:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2

        # Uses the private access token from above link
        with:
          token: ${{ secrets.GITHUB_TOKEN }}

      # Initialize or update each one recursively
      - name: Pull & update submodules recursively
        run: |
          git submodule update --init --recursive
          git submodule update --recursive --remote

      # Commit to the repo under the GitHub actions user to ensure we have
      # reasonable logging to trace back
      - name: Commit & push changes
        run: |
          git config --global user.email "actions@github.com"
          git config --global user.name "GitHub Actions - update submodules"
          git commit -am "Update submodules" || echo "No changes to commit"
      - name: Push to protected branch
        uses: CasperWA/push-protected@v2
        with:
          token: ${{ secrets.PUSH_PROTECTED_BRANCH_TOKEN }} # This requires a special token to be able to trigger checks on new branch creation
          ref: ${{ github.ref }}