title: Unable to execute spark job using SparkSubmitOperator
body: <p>I am able to run <code>Spark</code> job using <code>BashOperator</code> but I want to use <code>SparkSubmitOperator</code> for it using <code>Spark</code> <strong>standalone mode</strong>.</p>
  
  <hr>
  
  <p><a href="https://gist.github.com/mandar2174/c3f101d7d8c17bd28ff5134d3afdf025" rel="noreferrer">Here's</a> my <code>DAG</code> for <code>SparkSubmitOperator</code> and <em>stack-trace</em></p>
  
  <pre><code>args = {
      'owner': 'airflow',
      'start_date': datetime(2018, 5, 24)
  }
  dag = DAG('spark_job', default_args=args, schedule_interval="*/10 * * * *")
  
  operator = SparkSubmitOperator(
      task_id='spark_submit_job',
      application='/home/ubuntu/test.py',
      total_executor_cores='1',
      executor_cores='1',
      executor_memory='2g',
      num_executors='1',
      name='airflow-spark',
      verbose=False,
      driver_memory='1g',
      conf={'master':'spark://xx.xx.xx.xx:7077'},
      dag=dag,
  )
  </code></pre>
  
  <hr>
  
  <p>Looking at source for <a href="https://github.com/apache/incubator-airflow/blob/master/airflow/contrib/hooks/spark_submit_hook.py" rel="noreferrer"><code>spark_submit_hook</code></a> it seems <code>_resolve_connection()</code> always sets <code>master=yarn</code>. How can I change <code>master</code> <em>properties value</em> by <code>Spark</code> standalone master URL? Which properties I can set to run <code>Spark</code> job in <em>standalone mode</em>?</p>