Default DNS

Canonical Kubernetes includes a default DNS (Domain Name System) solution which is essential for internal cluster communication. When enabled, the DNS facilitates service discovery by assigning each service a DNS name.

Scaling DNS

Default DNS is scaled automatically through a Horizontal Pod Autoscaler (HPA) which monitors DNS pods’ CPU and memory resource usage and adjusts the number of replicas accordingly.

DNS scheduling

DNS pods are scheduled with topology spread constraints to spread them across the cluster nodes and zones when applicable. When Canonical Kubernetes detects that all pods are scheduled on the same node, it will restart the DNS pods to re-balance their distribution.

A priority class is assigned to DNS pods to ensure their scheduling before pods which are not node critical.

DNS maintenance

When performing maintenance operations on the cluster, please be aware that the pod disruption budget (PDB) will only allow one DNS pod to be taken down at a time.