The Platform Agent runs on each host to proxy requests from the Platform API Server to small worker applications. The primary reason for this is to make sure the Platform Agent process uses as little memory as possible. In this book, the Platform Agent refers to the union of the Platform Agent process and associated worker applications.

The Platform Agent knows how to gather the state of resources on its host, and to change the state of those resources. That is, the Platform Agent knows if a firewall port is open or closed, or if a package is installed and at which version. It also knows how to close that port if it is open, upgrade the package if it is old, or install the package if it is not installed.