In the context of the Machine Config Operator (MCO) in Red Hat OpenShift, on-cluster builds refer to the process of building an OS image directly on the OpenShift cluster, rather than building them outside the cluster (such as on a local machine or continuous integration (CI) pipeline) and then making a configuration change so that the cluster uses them. By doing this, we enable cluster administrators to have more control over the contents and configuration of their clusters’ OS image through a familiar interface (MachineConfigs and in the future, Dockerfiles).