Upgrading from version 6.x to 7.x

There are a number of breaking changes from version 6 to 7.

Environment Variables

6.x	7.x	Example
Environment variables all began with 'MARIADB_'	Environment variables begin with 'BF_DB_'	`MARIADB_BACKUP_COMPRESS_FILES=1` -> `BF_DB_BACKUP_COMPRESS_FILES=1`
Backup duration was configured by `MARIADB_BACKUP_KEEP_FOR_DAYS`	Backup duration is now `BF_DB_BACKUP_KEEP_FOR` and uses the Nu duration format	`MARIADB_BACKUP_KEEP_FOR_DAYS=28` -> `BF_DB_BACKUP_KEEP_FOR=28day`
SSL certificate duration was configured by `MARIADB_SSL_DAYS`	SSL certificate duration is now `BF_DB_SSL_EXPIRY` and uses the Nu duration format	`MARIADB_SSL_DAYS=3650` -> `BF_DB_SSL_EXPIRY=3650day`
`MARIADB_USERNAME` would be used as user, password and database name if they were not defined separately	This is now done by `BF_DB_APPLICATION` (`BF_DB_USERNAME`, `BF_DB_PASSWORD` and `BF_DB_DATABASE` can be used as overrides)	`BF_DB_APPLICATION=foo` `BF_DB_PASSWORD=bar` results in a user 'foo' with password 'bar' and database 'foo'

6.x	7.x
/var/lib/mysql	/data
/var/lib/backup	/backup