Coredns

 

CoreDNS is a flexible, extensible DNS server that can serve as the Kubernetes cluster DNS.CoreDNS is used by default.

Coredns Pods

There are 2 pods running for coredns under kube-system namespace

kubectl get pods -n kube-system

Coredns plugin information

Coredns pluging information is available in coredns file which is mapped to its config map.

kubectl get cm -n kube-system
kubectl describe cm coredns -n kube-system

Coredns service

Coredns service is used for resolving the service discovery on the basis of name instead of IP address of service. kube-dns service is running in kube-system

kubectl get svc -n kube-system

cluster dns information can be found in cat /var/lib/kubelet/config.yaml

Access the service with its name

Step 1 Create a service say nginx

 kubectl run nginx --image=nginx
 kubectl expose pod nginx --type=NodePort --port=80

Step 2 Add kube-dns service ip as nameserver in /etc/resolv.conf file

nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local

Step 3 Access the service with its name

host nginx
curl nginx