Runbooks

From AWS Well Architected Framework Concepts - https://wa.aws.amazon.com/wat.concept.runbook.en.html

Enable consistent and prompt responses to well understood events by documenting procedures in runbooks. Runbooks are the predefined procedures to achieve a specific outcome. Runbooks should contain the minimum information necessary to successfully perform the procedure. Start with a valid effective manual process, implement it in code and trigger automated execution where appropriate. This ensures consistency, speeds responses, and reduces errors caused by manual processes.

Using runbooks

Runbooks are usually written in the language an orchestrator (Terraform) or provisioner (Ansible/Chef/Puppet) would be able to parse for automation.

Another interesting tool to look at is Rundeck.

Is it a software

It is like any other program that requires a runtime.