I have a cluster running on GKE. I have my domain names registered in Cloudflare.
When I add/modify dns entries in Cloudflare, the propagation seems to be very fast (using tools like https://dnschecker.org/). However in my gke cluster, the pods don't resolve the new entries (I have to wait a long long time...). I have tried to add the dns resolver 1.1.1.1 in my kube-dns pods, then I could resolve the new entries in the kube-dns pods (kubedns and dnsmasq) but it still doesn't work for my other pods (the dnspolicy is correctly set to ClusterFirst).
Thanks for your help.
Thanks for your reply Pol Arroyo.
I found the answer, it has nothing to do with GKE, Cloudflare or a DNS resolver. In fact in my algorithm, I checked before the DNS update if the DNS pointed to the right IP. Doing so, dnsmasq keeped the answer that the DNS doesn't exist and I have to wait its cache to be updated.
You can change the DNS upstream nameservers [1] but keep in mind that DNS propagation can take up to 48h. Here is the example from the documentation:
apiVersion: v1
kind: ConfigMap
metadata:
name: kube-dns
namespace: kube-system
data:
upstreamNameservers: |
["1.1.1.1"]