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Deploying the DNS Cluster Add-on

Multiple examples, I went with coredns.

CoreDNS

CoreDNS is configured through a Corefile, and in Kubernetes, ConfigMap is used.

Apply CoreDNS ConfigMap

kubectl apply -f manifests/coredns.yaml

Output

serviceaccount "coredns" created
clusterrole "system:coredns" created
clusterrolebinding "system:coredns" created
configmap "coredns" created
deployment "coredns" created
service "kube-dns" created

kubectl get pod --all-namespaces -l k8s-app=coredns -o wide

Kube-DNS

Deploy the kube-dns cluster add-on

kubectl create -f manifests/kube-dns.yaml

Output

service "kube-dns" created
serviceaccount "kube-dns" created
configmap "kube-dns" created
deployment "kube-dns" created

List the pods created by the kube-dns deployment:

kubectl get pods -l k8s-app=kube-dns -n kube-system

Output

NAME                        READY     STATUS    RESTARTS   AGE
kube-dns-3097350089-gq015   3/3       Running   0          20s

Verification

Create a busybox deployment

kubectl run busybox --image=busybox --command -- sleep 3600

List the pod created by the busybox deployment

kubectl get pods -l run=busybox

Output

NAME                       READY     STATUS    RESTARTS   AGE
busybox-68654f944b-9hl4c   1/1       Running   0          21s

Retrieve the full name of the busybox pod

POD_NAME=$(kubectl get pods -l run=busybox -o jsonpath="{.items[0].metadata.name}")

> echo $POD_NAME
busybox-68654f944b-9hl4c

Execute a DNS lookup for the kubernetes service inside the busybox pod:

kubectl exec -ti $POD_NAME -- nslookup kubernetes

Output

Server:    10.98.96.10
Address 1: 10.98.96.10 kube-dns.kube-system.svc.cluster.local

Name:      kubernetes
Address 1: 10.98.96.1 kubernetes.default.svc.cluster.local