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CoreDNS

CoreDNS is the DNS server of Hikube Kubernetes clusters. It resolves the names of services and pods inside the cluster, and forwards queries for external names.

In the console​

CoreDNS is part of the Advanced Configuration of the Addons step: it is always present in the cluster and cannot be disabled. You can only override its configuration.

  1. At creation (Addons step) or from Edit > Extensions & Addons, expand the CoreDNS block in the Advanced Configuration section.
  2. Enter your values in Helm Configuration (YAML) — optional.
  3. Confirm with Next then Create cluster (creation) or Save (modification).
note

Clearing the field, or a line of the override, from Edit does not remove a value already applied to the cluster. Contact support to return to the default values.

On the cluster detail page, the DNS line of the Network section shows CoreDNS when a CoreDNS configuration is applied.

Override the configuration​

The YAML value is passed to the CoreDNS Helm chart, under the coredns key. For example, to set the number of replicas and the resources:

coredns-override.yaml
coredns:
  replicaCount: 2
  resources:
    limits:
      cpu: 500m
      memory: 256Mi
    requests:
      cpu: 100m
      memory: 128Mi

The available options (plugins, zones, cache, forward…) are described in the CoreDNS Helm chart.

Usage in the cluster​

# CoreDNS pods
kubectl get pods -A | grep coredns

# Test resolution from a pod
kubectl run dns-test --rm -it --image=busybox --restart=Never -- nslookup kubernetes.default

Best practices​

  • Keep at least 2 replicas to ensure DNS high availability.
  • Monitor memory: CoreDNS consumption grows with the number of services and queries.
  • Do not edit the CoreDNS ConfigMap by hand in the cluster: use the override in the console, otherwise your changes will be overwritten.