developer-roadmap/roadmaps/cloud-computing/content/control-loops--controllers@LBm5WZWdvXc_kNaeEDlX0.md

Control Loops & Controllers

The core operating principle of Kubernetes is the control loop. A controller watches the current state of a resource, compares it to the desired state defined in the spec, and takes corrective action if they differ. If a Deployment specifies three replicas and only two are running, the controller creates a third. This reconciliation loop runs continuously, making Kubernetes self-healing by design. Custom controllers and operators extend this pattern to manage application-specific resources using the same model.