Manually Add DNS Name Servers to K3S

To address missing DNS entries in some VMs, follow the steps below to manually add nameservers and search domain to k3s:

1. Create a file /etc/rancher/k3s/resolv.conf with the following data.

   vi /etc/rancher/k3s/resolv.conf

   Data:

   nameserver <DNS_IP_1>
   nameserver <DNS_IP_2>
   search <DOMAIN_1> <DOMAIN_2>

2. Create another file /etc/rancher/k3s/config.yaml with the following data.

   vi /etc/rancher/k3s/config.yaml

   Data:

   kubelet-arg:
     - "resolv-conf=/etc/rancher/k3s/resolv.conf"

3. Now restart the k3s service using following command.

   service k3s restart

4. Delete coredns pod using the following command.

   kubectl delete pod $(kubectl get pod -n kube-system | grep coredns | awk '{print $1}') -n kube-system

5. Run the following command to verify whether the DNS has been updated.

   kubectl debug -it $(kubectl get pod -n kube-system | grep coredns | awk '{print $1}') -n kube-system --image=busybox:1.28 --target=coredns -- cat /etc/resolv.conf