title: Mosquitto Authentication with MYSQL
body: <p>I would like to set up an own Mosquitto broker as a docker container. 
  This is not a problem since there are several ready to run containers out there. </p>
  
  <p>My problem is, how can i configure mosquitto in a way, that i can store the user login credentials, for authentication against mosquitto, in a Database like mysql instead of a password file. </p>
  
  <p>The background is, i would like to configure the access by a PHP script. 
  Im open to other methods instead of using a mysql db. </p>
  
  <p>But i think a db would be the best solution. 
  Im also open to alternatives to Mosquitto. I only would like to use MQTT with a DB based user authentication. </p>
  
  <p>thanks</p>