Priority Class


PriorityClassName is a Kubernetes feature used to prioritize Pods within a cluster. It allows you to assign a priority value to Pods, ensuring that high-priority Pods receive preferential treatment when it comes to resource allocation and scheduling.

How Does PriorityClassName Work?

PriorityClassName is primarily used to define the priority level for a Pod. It involves the following components:

  • Priority Class: A Kubernetes resource that defines a set of attributes (e.g., priority value) that can be associated with Pods.

  • Priority Value: An integer value assigned to a Priority Class. Higher values indicate higher priority. Pods with higher priority values are scheduled and allocated resources before Pods with lower priority values.

  • Default Priority Class: Kubernetes provides a default Priority Class with a priority value of 0. Any Pod that does not specify a Priority Class will be assigned this default priority value.

Kubernetes-Provided Priority Classes

Kubernetes provides below Priority Classes to help categorize workloads:

  • system-cluster-critical: Kubernetes system components that are critical to the entire cluster. Priority value: 2000001000

  • system-node-critical: Kubernetes system components that are critical to individual nodes. Priority value: 2000000000

These two Priority Classes ensure that essential system components receive the necessary resources for the proper functioning of the cluster.

Priority Classes for the components in Metakube Cluster

We have used the PriorityClassName to optimize resource allocation and scheduling in our MetaKube cluster.

Priority Class Definition

In addition to the Kubernetes provided ones, we have defined few more Priority Classes to categorize our workloads based on their importance and resource requirements. Each Priority Class is associated with a priority value.

Below is the list of priorityClassName that’s used in our cluster:

PriorityClassName Priority Value Component
kubermatic-master-controller-manager 500005000 kubermatic-master-controller-manager
kubermatic-seed-controller-manager 500005000 kubermatic-seed-controller-manager
user-cluster-apiserver 500002000 apiserver
user-cluster-controller-manager 500002000 controller-manager
user-cluster-scheduler 500002000 scheduler
user-cluster-machine-controller 500001000 machine-controller
user-cluster-kube-state-metrics 500000000 kube-state-metrics
user-cluster-cluster-autoscaler 500000000 cluster-autoscaler
user-cluster-prometheus 500001000 prometheus
user-cluster-etcd 500002000 etcd
user-cluster-nodeport-proxy-envoy 500005000 nodeport-proxy-envoy
user-cluster-csi-cinder-controllerplugin 500001000 csi-cinder-controllerplugin
system-cluster-critical calico-kube-controllers
system-node-critical canal

For more in-depth and comprehensive information on Kubernetes PriorityClassName and related concepts, we recommend referring to the official Kubernetes documentation.