Separate the client binary and engine flavour from the service name

[mcowser-p]

On Enterprise Linux running real MySQL (not MariaDB), this role cannot complete: the systemd unit is mysqld while the client binary is mysql, and mysql_daemon has to be both at once.

The three meanings

mysql_daemon is currently used as:

1. the systemd unit — service: name={{ mysql_daemon }}
2. the client binary — secure-installation.yml:25, command: {{ mysql_daemon }} -NBe "..." (six call sites)
3. the engine flavour — mysql_daemon == 'mariadb' / == 'mysql' (seven tests)

That is coherent wherever the three share a name: MariaDB everywhere, and MySQL on Debian, where the unit really is mysql. On EL + MySQL there is no value that works:

value	client	flavour	unit
mariadb (EL default)	not installed	wrong engine	wrong
mysqld	runs the server with client flags	matches neither test	correct
mysql	correct	correct	wrong

The mysqld case is the unpleasant one: mysqld -NBe "DELETE FROM mysql.user ..." tries to start a database with client arguments, blocks for ~100 seconds, then exits 1.

The change

Adds mysql_client and mysql_flavour, both defaulting to mysql_daemon, so every existing playbook is unaffected. Client invocations use mysql_client; flavour comparisons use mysql_flavour.

Callers who need the split set it explicitly:

mysql_daemon:  mysqld
mysql_client:  mysql
mysql_flavour: mysql

Testing

Found and verified running MySQL 8.0.46 on AlmaLinux 9 and MySQL 8.4 on Ubuntu 26.04. With the change, a host that had failed at mariadb --version on every run now completes the role cleanly. Debian is unaffected either way, which is why this has stayed hidden.

🤖 Generated with Claude Code

[mcowser-p]

Closing — I opened this prematurely. Keeping the change on a private fork for now; will resubmit if it's useful upstream later. Apologies for the noise.