title: why airflow errors out with "Can't connect to local MySQL server" and how to fix it?
body: <p>I am running the Airflow 1.8 on CentOS host that is part of a Cloudera Cluster.</p>
  
  <p>When I navigate to menu Data Profiling -> Ad-hoc query or Chart, I will always be prompted with error below:</p>
  
  <p><strong>Chart:</strong>
  <a href="https://i.stack.imgur.com/U7ZqG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/U7ZqG.png" alt="enter image description here"></a></p>
  
  <p><strong>Ad-hoc:</strong>
  <a href="https://i.stack.imgur.com/qVZhK.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qVZhK.png" alt="enter image description here"></a></p>
  
  <p>What am I missing here? if this is due to some packages were not included in the installation, how can I add them now?</p>
  
  <p>Thank you very much.</p>