The OKD installation program offers you flexibility. You can use the program to:
Deploy a cluster on provisioned infrastructure and the cluster it maintains.
Deploy a cluster on infrastructure that you prepare and maintain.
These two basic types of OKD clusters are frequently called:
Installer-provisioned infrastructure clusters.
User-provisioned infrastructure clusters.
Both cluster types have the following characteristics:
Highly available infrastructure with no single points of failure is available by default.
Administrators maintain control over what updates are applied and when.
The Agent-based Installer is part of the OKD Installer. The installer provides you with the flexibility of user-provisioned infrastructure (UPI) installation and the ease of use of the Assisted Installer (AI).
You can use the installation program to deploy both types of clusters. The installation program generates main assets such as Ignition config files for the bootstrap, master, and worker machines. You can start an OKD cluster with these three configurations and correctly configured infrastructure.
The OKD installation program uses a set of targets and dependencies to manage cluster installations. The installation program has a set of targets that it must achieve, and each target has a set of dependencies. Because each target is only concerned with its own dependencies, the installation program can act to achieve multiple targets in parallel with the ultimate target being a running cluster. The installation program recognizes and uses existing components instead of running commands to create them again because the program meets dependencies.