Demo External DNS

In this guide, you will learn how to install and configure ExternalDNS on a Kubernetes cluster to automatically manage DNS records in GoDaddy based on Ingress resources. This approach ensures that your services are always reachable via the correct domain names without manual DNS updates.

Cluster Overview

Before we begin, verify the current state of your cluster and the Traefik ingress controller.

kubectl get all

NAME                                READY   STATUS    RESTARTS   AGE
pod/whoami-8c9864b56-phnp7          1/1     Running   0          17m

NAME                TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGE
service/kubernetes  ClusterIP   10.96.0.1        <none>        443/TCP   14h
service/whoami      ClusterIP   10.104.155.171   <none>        80/TCP    17m

NAME                                READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/whoami              1/1     1            1           17m

NAME                                        DESIRED   CURRENT   READY   AGE
replicaset.apps/whoami-8c9864b56           1         1         1       17m

Check Traefik in the traefik namespace:

kubectl get pods -n traefik

NAME                             READY   STATUS    RESTARTS   AGE
traefik-7df9fd988f-j49ln         1/1     Running   0          18m

1. Install ExternalDNS via Helm

1. Add and update the ExternalDNS Helm repository:

   helm repo add external-dns https://kubernetes-sigs.github.io/external-dns/
   helm repo update
   

2. Create a values.yaml file with your GoDaddy credentials:

   # values.yaml
   provider:
     name: godaddy
   sources:
     - ingress
   domainFilters:
     - kubernetkk.xyz
   txtPrefix: external-dns
   txtOwnerId: owner-id
   extraArgs:
     - --godaddy-api-key=YOUR_GO_DADDY_API_KEY
     - --godaddy-api-secret=YOUR_GO_DADDY_API_SECRET
     - --godaddy-api-ote
   

Values Reference

3. Install ExternalDNS in the default namespace:

   helm install external-dns external-dns/external-dns \
     --values ./values.yaml --namespace default
   

4. Confirm the ExternalDNS pod is running:

   kubectl get pods -n default -l app.kubernetes.io/name=external-dns
   

5. View logs to verify it authenticates and syncs:

   kubectl logs -f deployment/external-dns -n default
   

   Expected log excerpt:

   time="2024-07-18T23:18:02Z" level=info msg="Using inCluster-config based on serviceaccount-token"
   time="2024-07-18T23:18:04Z" level=info msg="GoDaddy: 2 zones found"
   time="2024-07-18T23:18:04Z" level=info msg="All records are already up to date"
   

2. Create and Apply the Ingress

Define an Ingress that exposes the whoami service and instructs ExternalDNS to manage the DNS record whoami.kubernetkk.xyz pointing to your node IP (192.168.121.243 in this example).

# ingress.yaml
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: whoami-ingress
  annotations:
    external-dns.alpha.kubernetes.io/hostname: whoami.kubernetkk.xyz
    external-dns.alpha.kubernetes.io/target: "192.168.121.243"
spec:
  rules:
    - http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: whoami
                port:
                  number: 80

Apply the Ingress:

kubectl apply -f ingress.yaml

Watch ExternalDNS logs as it detects the new Ingress:

kubectl logs -f deployment/external-dns -n default

Look for a log entry like:

time="2024-07-18T23:21:05Z" level=info msg="GoDaddy: 3 changes will be done"

This confirms that ExternalDNS is creating the DNS record.

References

• ExternalDNS GitHub
• GoDaddy API Documentation
• Kubernetes Ingress
• Helm Charts