| title | notetype | date |
|---|---|---|
K8S Scheduling |
feed |
03-11-2021 |
[[K8S Scheduler]] is making sure that every [[K8S Pod]] is assigned to a [[K8S Node]]. Every pod that gets created has a property NodeName which is not set by default. kube-scheduler looks for pods with these fields unset and assigns them a node by setting the NodeName property.
The Pods are created before they are scheduled, and since the NodeName field is immutable, Scheduler can't just edit the pod. It has to create a [[K8S Binding Object]] and create a post request to the [[K8S Apiserver]].
There are multiple constraints that scheduler needs to take into consideration while deciding where to place a pod:
- [[01 Inbox/K8S Resource Requests and Limits]]
- [[K8S Node Selectors]]
- [[K8S Node Affinity]]
- [[K8S Taints and Tolerations]]
If there were no kube-scheduler on the cluster, you could create the pod with the NodeName already set.
Status: #💡