In every Spoke Environment that Apollo manages, there is a minimum set of functionality that needs to exist for Apollo to provide its workflows. This functionality is provided by the following components, which together make up the Spoke Control Plane.
Takes the current state of the Kubernetes environment, converts the Kubernetes object model into an Apollo object model, and sends that information back to the Apollo Hub.
expected-state-k8s, for example, provides information from the Kubernetes environment related to how many replicas of a Pod should be running and provides that back to the Hub. It is also responsible for collecting health information from all managed Entities and forwarding it to the Apollo Hub to report health.
An Apollo Agent responsible for managing Apollo entities of type helm-chart. It is necessary for lifecycle actions (install, config changes) on Helm Charts managed by Apollo that run in an Environment.
helm-chart-operator is also responsible for managing all of the other Spoke Control Plane services. It takes no dependencies on other services in the Spoke Control Plane and is the first service installed into a Spoke Environment.