This looks amazing and really interesting. Thank you so much for sharing!! I look forward to seeing how we can begin implementing.
I assume you are seeing some great performance improvements.
Well done!!
We use in production 3 node mautic cluster
3 DB connected between as galera cluster with percona cluster
Every instance connected to local HAProxy . HAProxy connected to local DB as primary and other node as backup.
So we can reboot and maintenance every machine step by step if needed without interrupt whole service.
For local.php just change port 3306(MySQL) to 3307 (HAProxy)