Ansible

Ansible is an open source IT automation engine covering provisioning, configuration management, application deployment and orchestration. It is free to use, benefits from thousands of contributors, and is stewarded by Red Hat, which also runs the Ansible Collaborative as a place for users, customers, partners and vendors to share automation content.

Being agentless is the design decision that explains its adoption. Configuration management tools before it required software installed on every managed machine, which meant an agent to deploy, maintain and secure on every host, and connecting over SSH instead removed that entire class of work.

Automation content being shared rather than written is what makes it practical at scale. Most tasks somebody needs to automate have been automated by somebody else, and a collaborative library means the work is assembling proven pieces rather than starting each time.

The free and commercial split should be understood before adopting. The engine costs nothing and Red Hat sells the platform around it, so an organisation can start at no cost and encounters the commercial question when it wants governance, support and scale. That is an honest sequence, and it means the evaluation costs nothing but time.