How do you provision and orchestrate bare-metal servers in 2019?

I only do this as so far as to run kubernetes on them - I use kubeadm and kubectl. I even made a github project for the most repetitive usecases: https://sanic.io

If I had to start a few thousand servers I'd just use terraform or fabric (https://www.fabfile.org/index.html)

I know its not shiny and new, but I still use Puppet to manage all of my physical and virtual servers.

Terraform and NixOps