kubernetes-the-hard-way/docs/12-dns-addon.md

Deploying the DNS Cluster Add-on

In this lab you will deploy the DNS add-on which provides DNS based service discovery to applications running inside the Kubernetes cluster.

The DNS Cluster Add-on

Deploy the kube-dns cluster add-on:

kubectl create -f https://storage.googleapis.com/kubernetes-the-hard-way/kube-dns.yaml

output

service "kube-dns" created
serviceaccount "kube-dns" created
configmap "kube-dns" created
deployment.extensions "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:1.28.4 --command -- sleep 3600

List the pod created by the busybox deployment:

kubectl get pods -l run=busybox

output

NAME                       READY     STATUS    RESTARTS   AGE
busybox-2125412808-mt2vb   1/1       Running   0          15s

Retrieve the full name of the busybox pod:

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

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

kubectl exec -ti $POD_NAME -- nslookup kubernetes

output

Server:    10.32.0.10
Address 1: 10.32.0.10 kube-dns.kube-system.svc.cluster.local

Name:      kubernetes
Address 1: 10.32.0.1 kubernetes.default.svc.cluster.local

Next: Smoke Test