Configuration Management (Ansible)

Configuration management is the practice of keeping servers in a known, consistent state through code: which packages are installed, which files and settings exist and which services run. Instead of logging in and changing each server by hand, you describe the desired state and a tool applies it to every machine.

Ansible is the most popular tool; it connects over SSH, needs no agent on the servers and uses YAML files called playbooks. Puppet, Chef and SaltStack are alternatives. Configuration management sets up the inside of servers, while Infrastructure as Code tools such as Terraform create the servers and networks themselves.