title: How to pass a conf to a scheduled DAG
body: <p>When the DAG is triggered manually there are multiple ways to pass the config. It could be done from the UI, via the airflow CLI using <code>--conf</code> argument &amp; using the REST API.</p>
  <p>But when a DAG is scheduled using a cron expression, the DAG always fails because the tasks in the DAG are expecting the values from <code>conf</code>.</p>
  <p>Is there a DAG level configuration which can be used to set &quot;default&quot; values for <code>conf</code> values (WITHOUT doing a null check in the Python code itself and hardcoding a default value)</p>
  <p>The reason I do not want to do this null check in the code itself is because I want the <code>conf</code> keys &amp; default values to be exposed via an Airflow API if possible</p>