title: Airflow, mark a task success or skip it before dag run
body: <p>We have a huge DAG, with many small and fast tasks and a few big and time consuming tasks. </p>
  
  <p>We want to run just a part of the DAG, and the easiest way that we found is to not add the task that we don't want to run. The problem is that our DAG has many co-dependencies, so it became a real challenge to not broke the dag when we want to skip some tasks. </p>
  
  <p>Its there a way to add a status to the task by default? (for every run), something like:</p>
  
  <pre><code># get the skip list from a env variable    
  task_list = models.Variable.get('list_of_tasks_to_skip')
  
  dag.skip(task_list)
  </code></pre>
  
  <p>or </p>
  
  <pre><code>for task in task_list:
      task.status = 'success'
  </code></pre>