Almost every Icinga 2 node setup requires the Icinga 2 API, as Icinga
Web connects to it, Icinga DB requires it, and although it's not clearly
mentioned anywhere in the documentation at the moment, it enables the
cluster communication functionality.
We are using a central DB-Cluster, therefor Icinga2 got a database on this remote cluster.
We used the icinga DB user, created during the step before, to import the DB schema.
For this, the additional GRANT options `ALTER` and `CREATE` where needed to install the schema successfully via:
```bash
mysql -u icinga -p icinga < /usr/share/icinga2-ido-mysql/schema/mysql.sql
```
Someone may find this a security problem. But I see two benefits:
* these GRANT options are only set for the icinga.* database
* this setup allows to execute also all later UPGRADE commands as the database user `icinga` - and not as the DB Administrator.
Two additional notes:
* I also included a small warning about the used default DB password
* sadly, I have no way to change this also in the provided mariadb-centos7.png image, so this is left unchanged at the moment
Removed rhel-8-server-optional-rpms, as it is not/no longer available for RHEL 8
Source: https://access.redhat.com/discussions/4171061#comment-1531531
> BaseOS and AppStream contain all software packages, which were available in extras and optional repositories before.
Debian switched to MariaDB in stretch and removed the mysql-server and
mysql-client packages in buster. The new mariadb packages are available
starting in Debian jessie.
