89 lines
1.9 KiB
Markdown
89 lines
1.9 KiB
Markdown
# Deploying the DNS Cluster Add-on
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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://github.com/coredns/coredns), to applications running inside the Kubernetes cluster.
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## The DNS Cluster Add-on
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Deploy the `coredns` cluster add-on:
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```
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kubectl apply --filename ./manifests/coredns-1.10.1.yaml
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```
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> output
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```
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serviceaccount/coredns created
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clusterrole.rbac.authorization.k8s.io/system:coredns created
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clusterrolebinding.rbac.authorization.k8s.io/system:coredns created
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configmap/coredns created
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service/kube-dns created
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deployment.apps/coredns created
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```
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List the pods created by the `kube-dns` deployment:
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```
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kubectl get pods --namespace kube-system --selector k8s-app=kube-dns
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```
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> output
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```
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NAME READY STATUS RESTARTS AGE
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coredns-8494f9c688-hh7r2 1/1 Running 0 10s
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coredns-8494f9c688-zqrj2 1/1 Running 0 10s
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```
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## Verification
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Create a `busybox` pod:
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```
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kubectl run busybox --image busybox:1.36.1 --command -- sleep infinity
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```
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List the pod created:
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```
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kubectl get pods --selector run=busybox
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```
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> output
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```
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NAME READY STATUS RESTARTS AGE
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busybox 1/1 Running 0 3s
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```
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Retrieve the full name of the `busybox` pod:
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```
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POD_NAME=$(kubectl get pods --selector run=busybox \
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--output jsonpath="{.items[0].metadata.name}")
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```
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Execute a DNS lookup for the `kubernetes` service inside the `busybox` pod:
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```
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kubectl exec --stdin --tty "${POD_NAME}" -- nslookup kubernetes
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```
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> output
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```
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Server: 10.32.0.10
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Address 1: 10.32.0.10 kube-dns.kube-system.svc.cluster.local
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Name: kubernetes
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Address 1: 10.32.0.1 kubernetes.default.svc.cluster.local
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```
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Delete the `busybox` pod:
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```
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kubectl delete pod "${POD_NAME}"
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```
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Next: [Smoke Test](./13-smoke-test.md)
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