Ansible is an agent-less IT automation tool developed in 2012 by Michael DeHaan, a former Red Hat associate. The Ansible design goals are for it to be minimal, consistent, secure, highly reliable, and easy to learn. The Ansible company was bought by Red Hat in October 2015, and now operates as part of Red Hat, Inc.
Ansible primarily runs in push mode using SSH, but you can also run Ansible using ansible-pull, where you can install Ansible on each agent, download the playbooks locally, and run them on individual machines. If there are a large number of machines (large is a relative term; but in this case, consider it to mean greater than 500), and you plan to deploy updates to the machines in parallel, this might be the right way to go about it. As we discussed before, either agent-full and agent-less systems have their pros and cons.
In the next section, we will...