Add Custom CoreDNS Configuration

It is desirable to extend CoreDNS with additional configuration to make changes that survive control plane maintenance. It is possible to create a ConfigMap in the kube-system namespace. The ConfigMap must be named coredns-additional-conf and contain a data entry with the key extra.conf. The value of the entry must be a string containing the additional configuration.

The following example shows how to add a custom DNS entry for example.abc:

apiVersion: v1
kind: ConfigMap
metadata:
  name: coredns-additional-conf
  namespace: kube-system
data:
    extra.conf: |
      example.abc:53 {
        hosts {
          1.2.3.4 example.abc
          2.3.4.5 server.example.abc
          fallthrough
        }
      }