ExternalDNS for Managed Kubernetes
Overview
ExternalDNS is a Kubernetes add-on that automates the management of public DNS records for Kubernetes resources, such as services and ingresses exposed outside the cluster. Unlike Kubernetes' internal DNS management, which is limited to internal cluster communication, ExternalDNS extends this functionality by delegating DNS record management to external DNS providers, such as IONOS Cloud DNS.
The ExternalDNS solution offers the following capabilities:
Empowers developers to manage DNS resources traditionally handled manually by infrastructure teams.
Ensures that DNS records are synchronized with the current state of the Kubernetes cluster.
Automates the management of many DNS records, reducing manual effort.
Simplifies DNS management while improving security.
By integrating ExternalDNS with the IONOS webhook, you can manage your IONOS domains directly within your Kubernetes cluster. This integration requires an IONOS API key or token from the account managing your domains. The following tutorial provides detailed technical instructions for deploying ExternalDNS with the IONOS webhook using the Helm chart.
Target audience
This tutorial is intended to help both developers and technical decision-makers.
What you will learn
The following tutorial provides detailed technical instructions for deploying ExternalDNS with the IONOS webhook using the Helm chart.
Before you begin
Ensure that you have the following before you begin:
A domain name registered with your domain provider, domain registrar, or a subdomain under your control.
A token from a user with privileges to manage zones and records with Cloud DNS.
An IONOS Managed Kubernetes cluster.
The kubectl installed on your local machine.
The Helm tool for installing a Helm chart.
Procedure
Follow these steps to set up ExternalDNS for your Managed Kubernetes with IONOS DNS Provider Cloud DNS:
Create a domain name
You must first Create a Primary Zone for your domain name with Cloud DNS and then Connect Domain Name to Cloud DNS.
Create configuration
Create a Helm values file for the ExternalDNS Helm chart that includes the webhook configuration. In this example, the values file is called external-dns-ionos-values.yaml.
---
# -- ExternalDNS Log level.
logLevel: debug # reduce in production
# -- if true, ExternalDNS will run in a namespaced scope (Role and Rolebinding will be namespaced too).
namespaced: false
triggerLoopOnEvent: true # if true, ExternalDNS will trigger a loop on every event (create/update/delete) on the resources it watches.
# -- Kubernetes resources to monitor for DNS entries.
sources:
- ingress
- service
provider:
name: webhook
webhook:
image:
repository: ghcr.io/ionos-cloud/external-dns-ionos-webhook
tag: latest
pullPolicy: IfNotPresent
env:
- name: LOG_LEVEL
value: debug
- name: IONOS_API_KEY
valueFrom:
secretKeyRef:
name: ionos-credentials
key: api-key
# The webhook server listens on localhost by default. Otherwise, you can set SERVER_HOST.
- name: SERVER_PORT
value: "8888" # default and recommended port for exposing webhook provider EPs
# The exposed server listens on all interfaces (0.0.0.0) by default. Otherwise, you can set METRICS_HOST.
- name: METRICS_PORT
value: "8080" # default and recommended port for exposing metrics and health EPs
- name: IONOS_DEBUG
value: "false" # change to "true" if you want see details of the http requests
- name: DRY_RUN
value: "false" # set to "false" when you want to allow making changes to your DNS resourcesCreate application manifest
Execute the following command to create an echo server application manifest in the echoserver_app.yaml file.
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: echoserver
namespace: echoserver
spec:
replicas: 1
selector:
matchLabels:
app: echoserver
template:
metadata:
labels:
app: echoserver
spec:
containers:
- image: ealen/echo-server:latest
imagePullPolicy: IfNotPresent
name: echoserver
ports:
- containerPort: 80
env:
- name: PORT
value: "80"
Create service for echo server application
Use the following content to create a Service manifest in the echoserver-svc.yaml file:
---
apiVersion: v1
kind: Service
metadata:
name: echoserver
namespace: echoserver
spec:
ports:
- port: 80
targetPort: 80
protocol: TCP
type: ClusterIP
selector:
app: echoserver
Install NGINX Ingress Controller
Execute the following commands to install the NGINX ingress controller in your cluster:
helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx
helm repo update
helm install ingress-nginx ingress-nginx/ingress-nginx --namespace ingress-nginx --create-namespaceCreate Ingress resource
Using the following content, create a Ingress manifest in the echoserver-ingress.yaml file:
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: echoserver
namespace: echoserver
annotations:
kubernetes.io/ingress.class: nginx
spec:
rules:
- host: app.example1.com #This is your subdomain / record name
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: echoserver
port:
number: 80
Final result
The deployment of ExternalDNS on Managed Kubernetes is complete. You can verify that the application deployed is functioning as expected using one of the following options:
Check that the echo server app runs on the subdomain you have specified by using the following command:
curl -I app.example1.com/?echo_code=404-300Result:
HTTP/1.1 404 Not Found
HTTP/1.1 300 Multiple ChoicesCheck that the new A and TXT records are created by using the following command:
curl --location --request GET 'https://dns.de-fra.ionos.com/records?filter.name=app' \
--header 'Authorization: Bearer eyJ0eXAiOiJKV1QiLCJraWQiOiI4MmE5' \
--data ''Conclusion
By following this tutorial, you have successfully deployed ExternalDNS with the IONOS webhook on a Managed Kubernetes cluster, enabling automated DNS record management for your applications. This integration streamlines DNS operations, reduces manual intervention, and ensures your DNS records stay synchronized with your cluster resources. You can now confidently manage DNS for your Kubernetes workloads using IONOS Cloud DNS.
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