My previous employer is one of the biggest game providers (in terms of daily users) in the world, and we ran a incredibly stable infrastructure based on VMs running on KVM with a home-built bash script to deploy our application servers everywhere.
Every bare-metal server is essentially setup identically using Saltstack, and then each virtual machine is setup identically on start as well. This allowed us to spin up, down or replace 1, 10, 100, 1000 stateless VMs for each game in a very short time period, with all the servers having identical configuration and deployed on.
Databases also have a similar setup, though a lot more complex as they are stateful and cant be removed with short notice. Stateful workloads are really hard and require more domain knowledge than a java application, so we decided to not virtualize the user-critical databases and keep them as they were to not embrace the complexity.
Every bare-metal server is essentially setup identically using Saltstack, and then each virtual machine is setup identically on start as well. This allowed us to spin up, down or replace 1, 10, 100, 1000 stateless VMs for each game in a very short time period, with all the servers having identical configuration and deployed on.
Databases also have a similar setup, though a lot more complex as they are stateful and cant be removed with short notice. Stateful workloads are really hard and require more domain knowledge than a java application, so we decided to not virtualize the user-critical databases and keep them as they were to not embrace the complexity.