Onboard a Service

Introduction

Advertising services to your DNS provider with ExternalDNS is as easy as adding an annotation for the hostname you wish to assign. This document will describe exposing a service to ExternalDNS.

Create an Annotation

Create a YAML configuration filed using the following template, which has annotations added under metadata to begin advertising the service with ExternalDNS.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx
        name: nginx
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-ns1
  annotations:
    external-dns.alpha.kubernetes.io/hostname: subdomain.domain.tld # Required
    external-dns.alpha.kubernetes.io/ttl: "120" # Optional: In Seconds
spec:
  selector:
    app: nginx
  type: LoadBalancer
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80

Add Annotations in a Deployed Ingress YAML File

If you already have an ingress deployed on your cluster, then use the following command to edit the YAML file.

kubectl edit service <service-name>

In the YAML file, under metadata, add the following annotations under the service API:

metadata:
  name: nginx-ns1
  annotations:
    external-dns.alpha.kubernetes.io/hostname: subdomain.domain.tld # Required
    external-dns.alpha.kubernetes.io/ttl: "120" # Optional: In Seconds

Verify the Record Creation

As ExternalDNS checks for record changes to be created, updated, or deleted every 60 seconds, give a minute or two for your changes to propagate. You can also view the logs of the external-dns pod to see your DNS records change in real time.

After sufficient time has passed, either check the user interface of the DNS provider or use dig, nslookup, or another similar DNS lookup tool to confirm changes are published.