How to schedule a GitHub Actions nightly build, but run it only when there where recent code changes?

I want to have automatic nightly builds (daily snapshots from the development branch) with GitHub Actions.

To reduce billing costs, I want the GitHub Actions workflow to trigger (or do stuff) only when there where new commits since the last GitHub Actions nightly build workflow run.

How to schedule a GitHub Actions nightly build, but run it only when there where code changes since last nightly run?

Be aware, that there are also other GitHub Actions workflows, that shall not interfere with this nightly build.

You can do something like this:

1. first add this job:

  check_date:
    runs-on: ubuntu-latest
    name: Check latest commit
    outputs:
      should_run: ${{ steps.should_run.outputs.should_run }}
    steps:
      - uses: actions/checkout@v2
      - name: print latest_commit
        run: echo ${{ github.sha }}

      - id: should_run
        continue-on-error: true
        name: check latest commit is less than a day
        if: ${{ github.event_name == 'schedule' }}
        run: test -z $(git rev-list  --after="24 hours"  ${{ github.sha }}) && echo "::set-output name=should_run::false"

2. add this to all other jobs in your workflow:

    needs: check_date
    if: ${{ needs.check_date.outputs.should_run != 'false' }}

for example:

  do_something:
    needs: check_date
    if: ${{ needs.check_date.outputs.should_run != 'false' }}
    runs-on: windows-latest
    name: do something.
    steps:
      - uses: actions/checkout@v2

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