Kubernetes the hard way on bare metal/VMs — Setting up DNS

Part of the Kubernetes the hard way on bare metal/VM. This is designed for beginners.

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Introduction

This guide is part of the Kubernetes the hard way on bare metal/VMs series. On its own this may be useful to you however since it’s tailored for the series, it may not be completely suited to your needs.

Setting up DNS

You’ll be using CoreDNS from Kelsey’s guide

curl https://raw.githubusercontent.com/coredns/deployment/coredns-1.14.0/kubernetes/coredns.yaml.sed -o coredns.yaml.sed
curl https://raw.githubusercontent.com/coredns/deployment/coredns-1.14.0/kubernetes/deploy.sh -o deploy.sh
bash ./deploy.sh -s -i 10.32.0.10 > coredns.yaml
kubectl apply -f coredns.yaml

Check it has been deployed

kubectl get pods -l k8s-app=kube-dns -n kube-system -w
#Results
NAME                       READY   STATUS    RESTARTS   AGE
coredns-699f8ddd77-fmc67   1/1     Running   0          40s
coredns-699f8ddd77-zb7gw   1/1     Running   0          42

DNS Tests

Of course, you should test everything to make sure your new DNS bits work as expected, so let’s do just that.

kubectl apply -f https://k8s.io/examples/admin/dns/dnsutils.yaml
kubectl exec -ti dnsutils -- nslookup kubernetes
##Results
Server:         10.32.0.10
Address:        10.32.0.10#53
Name:   kubernetes.default.svc.cluster.local
Address: 10.32.0.1

If you don’t see the results above, it’s likely the coredns pods have errors. use kubectl describe & logs to diagnose these.

Conclusion

You’ve configured the DNS for the cluster and without realising it, just finished setting up the entire cluster!

Next: Testing everything