title: MongoDB set user as admin of selected databases
body: <p>I need to create user in MongoDB with "root" role but only to few selected databases (database_one and database_two).
  An my questions are: </p>
  
  <ol>
  <li>In which database should I create user?</li>
  <li>Do I need to create custom roles? With what settings?</li>
  <li>Which roles should I grant to user?</li>
  </ol>
  
  <p>My plan was that I create user in DB admin, set roles dbAdmin, userAdmin, readWrite with both databases (database_one and database_two). But in this case I'm not able to connect as this user.
  Can you help me how to setup user and his roles?</p>