How to use Cloudflare 1.1.1.1 with Kubernetes DNS

I'd like to use Cloudflare's 1.1.1.1 and 1.0.0.1 nameservers in Kubernetes, alongside DNS over TLS. It looks like I can do it using core-dns. I need to setup the following somehow:

What should my ConfigMap look like? I've started it below:

apiVersion: v1
kind: ConfigMap
data:
  upstreamNameservers: |
    ["1.1.1.1", "1.0.0.1"]

Solution

You can configure your core-dns kubectl -n kube-system edit configmap coredns and add to end of corefile:

. {
    forward . tls://1.1.1.1 tls://1.0.0.1 {
       tls_servername cloudflare-dns.com
       health_check 5s
    }
    cache 30
}

and than save new configuration and restart core-dns pods.

kubectl get pod -n kube-system | grep core-dns | cut -d " " -f1 - | xargs -n1 -P 10 kubectl delete pod -n kube-system