title: Wait for triggered DAG
body: <p>I have one control dag which triggers two other dags. The two dags should run sequentially and not in parallel. 
  I tried solving the problem like this:</p>
  
  <pre><code>TriggerDag (using BashOp) -&gt; ExternalDagSensor -&gt; TriggerDag (using BashOp) -&gt; ExternalDagSensor.
  </code></pre>
  
  <p>My problem is that the triggered DAG does get a specific <code>execution_date</code> (specific down to the seconds, not 00:00 for minutes and seconds). The DagSensor now uses the <code>execution_time</code> of the control dag to poke for the dependent dag and so the sensor never gets triggered, as the dependent dag has a different <code>execution_time</code>.</p>
  
  <p>My questions:</p>
  
  <ol>
  <li>Is the <code>Trigger-&gt;Sensor-&gt;Trigger-&gt;Sensor</code> pattern the right way to trigger DAGs sequentially?</li>
  <li><p>If yes: How do I get </p>
  
  <p>a) either the <code>execution_date</code> of the dependent DAG after it has been triggered by the controller DAG (can then be passed to the sensor as argument) </p>
  
  <p>or</p>
  
  <p>b) the <code>execution_date</code> of the dependent DAG to be the same as the control DAG</p></li>
  </ol>
  
  <p>If possible I do not want to query the metadata database to get the execution_time of the dependent DAG run.</p>