Save MariaDB password in config file

[Zarquan]

To enable the create-user script to access the database after the initial deployment, we should save the generated username/password in a text file in the admin user's home directory on the Zeppelin node.

/home/fedora/mariadb.cnf

We can set the username and password used by all the MariaDB and MySQL clients, e.g. mysql and mysqldump.

[client]
user = albert
password = eiwu1Aip-Ahbae3Ah
host = 127.0.0.1

We can add a symlink to map this to the hidden config file that the MariaDb client looks for by default.

ln -s /home/fedora/mariadb.cnf   /home/fedora/.my.cnf

With this in place, we should be able invoke a mysql or mysqldump command via ssh without needing to know the local password.

Putting the passwords directly into the hidden file just makes it harder for us. The bad guys all know where the hidden file is, so it doesn't gain anything in security. It just create yet another hidden file that we need to keep track of which can get forgotten if we can't see it.

We should avoid using the obfuscated .mylogin.cnf password file that the MySQL mysql_config_editor creates, because it isn't compatible with MariaDB

Putting the password file in fedora's home directory means it is visible from a notebook running in Zeppelin, but that should be fixed once we move Zeppelin to a separate Unix account.

[Zarquan]

Fixed in #712