update_submodules.yml

name: Update submodules
on:
  schedule:
    - cron: '17 8 10 * *' # Run monthly on the 10th, at 8:17am
  workflow_dispatch: # Can be run manually from GitHub UI

jobs:
  update:
    runs-on: ubuntu-latest
    permissions:
      contents: write # Permit git push
      pull-requests: write
    steps:
      - name: Set TODAY env var
        run: echo "TODAY=$(date +'%Y-%m-%d')" >> $GITHUB_ENV

      - name: Checkout project
        uses: actions/checkout@v4
        with:
          submodules: true

      - name: Create branch
        run: git checkout -b submodules-update-$TODAY

      - name: Run submodule updates
        run: git submodule update --remote --checkout

      - name: Configure git user
        run: |
          git config user.name ${{ github.actor }}
          git config user.email ${{ github.actor }}@users.noreply.github.com

      - name: Commit
        run: |
          git add .
          git commit -m "Update submodules $TODAY"

      - name: Push branch
        run: |
          git config push.autoSetupRemote true
          git push

      - name: Open pull request
        env:
          GH_TOKEN: ${{ github.token }}
        run: |
          gh pr create \
            --fill \
            --reviewer eliotsykes \
            --base ${{ github.ref_name }}