Ansible is a python command line program. In its basic usage, it reads a list of server hosts (the "inventory"), has access to a library of command line scripts ("modules") that might be run on the servers, and reads a configuration file ("playbook") which specifies modules to run on each server, and parameters to pass to each module. Using the sequence defined in the playbook, it connects to each server with SSH, copies (SFTP or SCP) the module up to the server, executes it remotely, then deletes it.
Ansible does not require a database or any long-running process, and you only need to install it on a single machine. The remote machines being managed by Ansible only need an ssh server and a version of Python 2 with json support, though it is possible to use Ansible to install Python remotely as long as the machine has an ssh server running.