Ansible

Ansible runs automation from a control machine over SSH or an API. You write the desired work in a playbook, group machines in an inventory, and let Ansible run the tasks in order.

It is often used for configuration management: install packages, write config files, restart services, and make sure a machine is in the shape you expect. It can also drive cloud provisioning through collections such as azure.azcollection, which is why it sits somewhere between classic server automation and Infrastructure as Code.

The nice part is the lack of an agent. There is no daemon to install on every target host. The trade-off is that you need clean inventories, good idempotent tasks, and enough discipline to avoid turning playbooks into long shell scripts with YAML around them.