How to Use External DNS for Kubernetes

Kubernetes is a powerful tool for container orchestration, and it makes managing large, complex deployments much simpler. However, one challenge with Kubernetes is managing DNS records for your services. External DNS is a Kubernetes add-on that can automatically manage DNS records for your services, making it easier to manage and scale your Kubernetes deployment.

In this article, we will discuss how to use External DNS for Kubernetes.

1. Installing External DNS

The first step to using External DNS for Kubernetes is to install it on your cluster. You can install External DNS using a Helm chart or by running a YAML file. Here are the commands to install External DNS using a YAML file:

$ kubectl apply -f https://raw.githubusercontent.com/kubernetes-sigs/external-dns/master/docs/contributing/crd-source/crd-manifest.yaml
$ kubectl apply -f https://raw.githubusercontent.com/kubernetes-sigs/external-dns/master/docs/contributing/crd-source/crd-manifest.yaml
$ kubectl apply -f https://raw.githubusercontent.com/kubernetes-sigs/external-dns/master/docs/contributing/crd-source/crd-manifest.yaml

2. Configuring External DNS

Once you have installed External DNS, you need to configure it to work with your DNS provider. External DNS supports a wide range of DNS providers, including AWS Route53, Google Cloud DNS, and Microsoft Azure DNS. You can configure External DNS using a Kubernetes ConfigMap.

Here is an example ConfigMap for External DNS that uses AWS Route53 as the DNS provider:

apiVersion: v1
kind: ConfigMap
metadata:
  name: external-dns
data:
  domainFilters: |
    - mydomain.com
  aws:
    region: us-west-2
    zoneType: public

3. Creating Kubernetes Services

Now that you have installed and configured External DNS, you can create Kubernetes services that will automatically create DNS records. When you create a Kubernetes service, you can specify a hostname using the metadata.annotations.external-dns.alpha.kubernetes.io/hostname annotation.

Here is an example of creating a Kubernetes service with a hostname:

apiVersion: v1
kind: Service
metadata:
  name: my-service
  annotations:
    external-dns.alpha.kubernetes.io/hostname: my-service.mydomain.com
spec:
  selector:
    app: my-app
  ports:
  - name: http
    port: 80
    targetPort: http
  type: LoadBalancer

4. Verifying DNS Records

After you have created your Kubernetes service, External DNS will automatically create DNS records for it. You can verify that the DNS records are created by using a DNS lookup tool, such as dig.

Here is an example of using dig to verify a DNS record:

$ dig my-service.mydomain.com

You should see the IP address of your Kubernetes service in the DNS response.

Using External DNS for Kubernetes can simplify the management of DNS records for your Kubernetes services. By following the steps outlined in this article, you can quickly set up and configure External DNS for your Kubernetes deployment. If you encounter any issues or have any questions, the External DNS documentation is a great resource for troubleshooting.

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That's it for this post. Keep practicing and have fun. Leave your comments if any.