82 lines
1.8 KiB
Markdown
82 lines
1.8 KiB
Markdown
# Deploying the DNS Cluster Add-on
|
|
|
|
In this lab you will deploy the [DNS add-on](https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/) which provides DNS based service discovery, backed by [CoreDNS](https://coredns.io/), to applications running inside the Kubernetes cluster.
|
|
|
|
## The DNS Cluster Add-on
|
|
|
|
Deploy the `coredns` cluster add-on:
|
|
|
|
```
|
|
kubectl apply -f https://storage.googleapis.com/kubernetes-the-hard-way/coredns-1.8.0.yaml
|
|
```
|
|
|
|
> output
|
|
|
|
```
|
|
serviceaccount/coredns created
|
|
clusterrole.rbac.authorization.k8s.io/system:coredns created
|
|
clusterrolebinding.rbac.authorization.k8s.io/system:coredns created
|
|
configmap/coredns created
|
|
deployment.apps/coredns created
|
|
service/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
|
|
coredns-5677dc4cdb-d8rtv 1/1 Running 0 30s
|
|
coredns-5677dc4cdb-m8n69 1/1 Running 0 30s
|
|
```
|
|
|
|
## Verification
|
|
|
|
Create a `busybox` deployment:
|
|
|
|
```
|
|
kubectl run busybox --image=busybox:1.28 --command -- sleep 3600
|
|
```
|
|
|
|
List the pod created by the `busybox` deployment:
|
|
|
|
```
|
|
kubectl get pods -l run=busybox
|
|
```
|
|
|
|
> output
|
|
|
|
```
|
|
NAME READY STATUS RESTARTS AGE
|
|
busybox 1/1 Running 0 3s
|
|
```
|
|
|
|
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](13-smoke-test.md)
|