Installation and extension docs and architecture

[guigomcha]

Hi apologies if this seems obvious but I have been reading so many different tutorials, issues and examples that I no longer know what is the current apporach.

I understand that the static pod kube-scheduler that we have in recent K8s is compatible with this framework. However, I see that there are two images being generated in the repo, "controller" and the "kube-scheduler", which does not seems to be documented as part of the kube-scheduller repo upstream.

• Are plugins part of the controller or the kube-scheduler? why would the controller be placed in a different namespace (check manifests/install/all-in-one.yaml
• how does the kube-scheduller interact with the controller?
• Do I really have to replace the kube-scheduler image in order to integrate a new plugin? or just with the missing flag --config pointing to a KubeSchedulerConfiguration ?
• I think that KubeSchedulerConfiguration is not really a CRD right? There is no way to install a new plugin without going to the control-plane nodes and changing this file right?

Thanks a lot in advanced

[Huang-Wei]

• Controllers complement schedulers, in some cases optional. For example, a controller is well-suited to reflect the current status - such as how many Pods are scheduled in a PodGroup - providing users with more detailed information.
• Scheduler plugins do not interact with controllers. Instead, they work with the spec of dependent resources, such as Pods, Nodes, CR objects, and similar entities.
• The provided images are mainly intended to ease spinning up a secondary scheduler, allowing you to keep the default kube-scheduler unchanged - especially useful in cloud environments where you have no control over the control plane. You can ignore the images as well, for example, some users directly vendor specific plugin in their Go code.
• KubeSchedulerConfiguration is not a CRD; it’s a configuration file read by kube-scheduler during initialization. You must modify this file and restart kube-scheduler for changes to take effect.